Actual source code: snes.c

  1: #include <petsc/private/snesimpl.h>
  2: #include <petscdmshell.h>
  3: #include <petscdraw.h>
  4: #include <petscds.h>
  5: #include <petscdmadaptor.h>
  6: #include <petscconvest.h>

  8: PetscBool         SNESRegisterAllCalled = PETSC_FALSE;
  9: PetscFunctionList SNESList              = NULL;

 11: /* Logging support */
 12: PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
 13: PetscLogEvent SNES_Solve, SNES_Setup, SNES_FunctionEval, SNES_JacobianEval, SNES_NGSEval, SNES_NGSFuncEval, SNES_NPCSolve, SNES_ObjectiveEval;

 15: /*@
 16:    SNESSetErrorIfNotConverged - Causes SNESSolve() to generate an error if the solver has not converged.

 18:    Logically Collective on SNES

 20:    Input Parameters:
 21: +  snes - iterative context obtained from SNESCreate()
 22: -  flg - PETSC_TRUE indicates you want the error generated

 24:    Options database keys:
 25: .  -snes_error_if_not_converged <true,false> - cause an immediate error condition and stop the program if the solver does not converge

 27:    Level: intermediate

 29:    Notes:
 30:     Normally PETSc continues if a linear solver fails to converge, you can call SNESGetConvergedReason() after a SNESSolve()
 31:     to determine if it has converged.

 33: .seealso: SNESGetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIfNotConverged()
 34: @*/
 35: PetscErrorCode  SNESSetErrorIfNotConverged(SNES snes,PetscBool flg)
 36: {
 39:   snes->errorifnotconverged = flg;
 40:   return 0;
 41: }

 43: /*@
 44:    SNESGetErrorIfNotConverged - Will SNESSolve() generate an error if the solver does not converge?

 46:    Not Collective

 48:    Input Parameter:
 49: .  snes - iterative context obtained from SNESCreate()

 51:    Output Parameter:
 52: .  flag - PETSC_TRUE if it will generate an error, else PETSC_FALSE

 54:    Level: intermediate

 56: .seealso:  SNESSetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIfNotConverged()
 57: @*/
 58: PetscErrorCode  SNESGetErrorIfNotConverged(SNES snes,PetscBool  *flag)
 59: {
 62:   *flag = snes->errorifnotconverged;
 63:   return 0;
 64: }

 66: /*@
 67:     SNESSetAlwaysComputesFinalResidual - does the SNES always compute the residual at the final solution?

 69:    Logically Collective on SNES

 71:     Input Parameters:
 72: +   snes - the shell SNES
 73: -   flg - is the residual computed?

 75:    Level: advanced

 77: .seealso: SNESGetAlwaysComputesFinalResidual()
 78: @*/
 79: PetscErrorCode  SNESSetAlwaysComputesFinalResidual(SNES snes, PetscBool flg)
 80: {
 82:   snes->alwayscomputesfinalresidual = flg;
 83:   return 0;
 84: }

 86: /*@
 87:     SNESGetAlwaysComputesFinalResidual - does the SNES always compute the residual at the final solution?

 89:    Logically Collective on SNES

 91:     Input Parameter:
 92: .   snes - the shell SNES

 94:     Output Parameter:
 95: .   flg - is the residual computed?

 97:    Level: advanced

 99: .seealso: SNESSetAlwaysComputesFinalResidual()
100: @*/
101: PetscErrorCode  SNESGetAlwaysComputesFinalResidual(SNES snes, PetscBool *flg)
102: {
104:   *flg = snes->alwayscomputesfinalresidual;
105:   return 0;
106: }

108: /*@
109:    SNESSetFunctionDomainError - tells SNES that the input vector to your SNESFunction is not
110:      in the functions domain. For example, negative pressure.

112:    Logically Collective on SNES

114:    Input Parameters:
115: .  snes - the SNES context

117:    Level: advanced

119: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction
120: @*/
121: PetscErrorCode  SNESSetFunctionDomainError(SNES snes)
122: {
125:   snes->domainerror = PETSC_TRUE;
126:   return 0;
127: }

129: /*@
130:    SNESSetJacobianDomainError - tells SNES that computeJacobian does not make sense any more. For example there is a negative element transformation.

132:    Logically Collective on SNES

134:    Input Parameters:
135: .  snes - the SNES context

137:    Level: advanced

139: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction(), SNESSetFunctionDomainError()
140: @*/
141: PetscErrorCode SNESSetJacobianDomainError(SNES snes)
142: {
145:   snes->jacobiandomainerror = PETSC_TRUE;
146:   return 0;
147: }

149: /*@
150:    SNESSetCheckJacobianDomainError - if or not to check jacobian domain error after each Jacobian evaluation. By default, we check Jacobian domain error
151:    in the debug mode, and do not check it in the optimized mode.

153:    Logically Collective on SNES

155:    Input Parameters:
156: +  snes - the SNES context
157: -  flg  - indicates if or not to check jacobian domain error after each Jacobian evaluation

159:    Level: advanced

161: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction(), SNESSetFunctionDomainError(), SNESGetCheckJacobianDomainError()
162: @*/
163: PetscErrorCode SNESSetCheckJacobianDomainError(SNES snes, PetscBool flg)
164: {
166:   snes->checkjacdomainerror = flg;
167:   return 0;
168: }

170: /*@
171:    SNESGetCheckJacobianDomainError - Get an indicator whether or not we are checking Jacobian domain errors after each Jacobian evaluation.

173:    Logically Collective on SNES

175:    Input Parameters:
176: .  snes - the SNES context

178:    Output Parameters:
179: .  flg  - PETSC_FALSE indicates that we don't check jacobian domain errors after each Jacobian evaluation

181:    Level: advanced

183: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction(), SNESSetFunctionDomainError(), SNESSetCheckJacobianDomainError()
184: @*/
185: PetscErrorCode SNESGetCheckJacobianDomainError(SNES snes, PetscBool *flg)
186: {
189:   *flg = snes->checkjacdomainerror;
190:   return 0;
191: }

193: /*@
194:    SNESGetFunctionDomainError - Gets the status of the domain error after a call to SNESComputeFunction;

196:    Logically Collective on SNES

198:    Input Parameters:
199: .  snes - the SNES context

201:    Output Parameters:
202: .  domainerror - Set to PETSC_TRUE if there's a domain error; PETSC_FALSE otherwise.

204:    Level: advanced

206: .seealso: SNESSetFunctionDomainError(), SNESComputeFunction()
207: @*/
208: PetscErrorCode  SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
209: {
212:   *domainerror = snes->domainerror;
213:   return 0;
214: }

216: /*@
217:    SNESGetJacobianDomainError - Gets the status of the Jacobian domain error after a call to SNESComputeJacobian;

219:    Logically Collective on SNES

221:    Input Parameters:
222: .  snes - the SNES context

224:    Output Parameters:
225: .  domainerror - Set to PETSC_TRUE if there's a jacobian domain error; PETSC_FALSE otherwise.

227:    Level: advanced

229: .seealso: SNESSetFunctionDomainError(), SNESComputeFunction(),SNESGetFunctionDomainError()
230: @*/
231: PetscErrorCode SNESGetJacobianDomainError(SNES snes, PetscBool *domainerror)
232: {
235:   *domainerror = snes->jacobiandomainerror;
236:   return 0;
237: }

239: /*@C
240:   SNESLoad - Loads a SNES that has been stored in binary  with SNESView().

242:   Collective on PetscViewer

244:   Input Parameters:
245: + newdm - the newly loaded SNES, this needs to have been created with SNESCreate() or
246:            some related function before a call to SNESLoad().
247: - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()

249:    Level: intermediate

251:   Notes:
252:    The type is determined by the data in the file, any type set into the SNES before this call is ignored.

254:   Notes for advanced users:
255:   Most users should not need to know the details of the binary storage
256:   format, since SNESLoad() and TSView() completely hide these details.
257:   But for anyone who's interested, the standard binary matrix storage
258:   format is
259: .vb
260:      has not yet been determined
261: .ve

263: .seealso: PetscViewerBinaryOpen(), SNESView(), MatLoad(), VecLoad()
264: @*/
265: PetscErrorCode  SNESLoad(SNES snes, PetscViewer viewer)
266: {
267:   PetscBool      isbinary;
268:   PetscInt       classid;
269:   char           type[256];
270:   KSP            ksp;
271:   DM             dm;
272:   DMSNES         dmsnes;

276:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);

279:   PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);
281:   PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);
282:   SNESSetType(snes, type);
283:   if (snes->ops->load) {
284:     (*snes->ops->load)(snes,viewer);
285:   }
286:   SNESGetDM(snes,&dm);
287:   DMGetDMSNES(dm,&dmsnes);
288:   DMSNESLoad(dmsnes,viewer);
289:   SNESGetKSP(snes,&ksp);
290:   KSPLoad(ksp,viewer);
291:   return 0;
292: }

294: #include <petscdraw.h>
295: #if defined(PETSC_HAVE_SAWS)
296: #include <petscviewersaws.h>
297: #endif

299: /*@C
300:    SNESViewFromOptions - View from Options

302:    Collective on SNES

304:    Input Parameters:
305: +  A - the application ordering context
306: .  obj - Optional object
307: -  name - command line option

309:    Level: intermediate
310: .seealso:  SNES, SNESView, PetscObjectViewFromOptions(), SNESCreate()
311: @*/
312: PetscErrorCode  SNESViewFromOptions(SNES A,PetscObject obj,const char name[])
313: {
315:   PetscObjectViewFromOptions((PetscObject)A,obj,name);
316:   return 0;
317: }

319: PETSC_EXTERN PetscErrorCode SNESComputeJacobian_DMDA(SNES,Vec,Mat,Mat,void*);

321: /*@C
322:    SNESView - Prints the SNES data structure.

324:    Collective on SNES

326:    Input Parameters:
327: +  SNES - the SNES context
328: -  viewer - visualization context

330:    Options Database Key:
331: .  -snes_view - Calls SNESView() at end of SNESSolve()

333:    Notes:
334:    The available visualization contexts include
335: +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
336: -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
337:          output where only the first processor opens
338:          the file.  All other processors send their
339:          data to the first processor to print.

341:    The available formats include
342: +     PETSC_VIEWER_DEFAULT - standard output (default)
343: -     PETSC_VIEWER_ASCII_INFO_DETAIL - more verbose output for SNESNASM

345:    The user can open an alternative visualization context with
346:    PetscViewerASCIIOpen() - output to a specified file.

348:   In the debugger you can do "call SNESView(snes,0)" to display the SNES solver. (The same holds for any PETSc object viewer).

350:    Level: beginner

352: .seealso: PetscViewerASCIIOpen()
353: @*/
354: PetscErrorCode  SNESView(SNES snes,PetscViewer viewer)
355: {
356:   SNESKSPEW      *kctx;
357:   KSP            ksp;
358:   SNESLineSearch linesearch;
359:   PetscBool      iascii,isstring,isbinary,isdraw;
360:   DMSNES         dmsnes;
361: #if defined(PETSC_HAVE_SAWS)
362:   PetscBool      issaws;
363: #endif

366:   if (!viewer) {
367:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&viewer);
368:   }

372:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
373:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);
374:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
375:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
376: #if defined(PETSC_HAVE_SAWS)
377:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);
378: #endif
379:   if (iascii) {
380:     SNESNormSchedule normschedule;
381:     DM               dm;
382:     PetscErrorCode   (*cJ)(SNES,Vec,Mat,Mat,void*);
383:     void             *ctx;
384:     const char       *pre = "";

386:     PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer);
387:     if (!snes->setupcalled) {
388:       PetscViewerASCIIPrintf(viewer,"  SNES has not been set up so information may be incomplete\n");
389:     }
390:     if (snes->ops->view) {
391:       PetscViewerASCIIPushTab(viewer);
392:       (*snes->ops->view)(snes,viewer);
393:       PetscViewerASCIIPopTab(viewer);
394:     }
395:     PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);
396:     PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%g, absolute=%g, solution=%g\n",(double)snes->rtol,(double)snes->abstol,(double)snes->stol);
397:     if (snes->usesksp) {
398:       PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);
399:     }
400:     PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);
401:     SNESGetNormSchedule(snes, &normschedule);
402:     if (normschedule > 0) PetscViewerASCIIPrintf(viewer,"  norm schedule %s\n",SNESNormSchedules[normschedule]);
403:     if (snes->gridsequence) {
404:       PetscViewerASCIIPrintf(viewer,"  total number of grid sequence refinements=%D\n",snes->gridsequence);
405:     }
406:     if (snes->ksp_ewconv) {
407:       kctx = (SNESKSPEW*)snes->kspconvctx;
408:       if (kctx) {
409:         PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);
410:         PetscViewerASCIIPrintf(viewer,"    rtol_0=%g, rtol_max=%g, threshold=%g\n",(double)kctx->rtol_0,(double)kctx->rtol_max,(double)kctx->threshold);
411:         PetscViewerASCIIPrintf(viewer,"    gamma=%g, alpha=%g, alpha2=%g\n",(double)kctx->gamma,(double)kctx->alpha,(double)kctx->alpha2);
412:       }
413:     }
414:     if (snes->lagpreconditioner == -1) {
415:       PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");
416:     } else if (snes->lagpreconditioner > 1) {
417:       PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);
418:     }
419:     if (snes->lagjacobian == -1) {
420:       PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");
421:     } else if (snes->lagjacobian > 1) {
422:       PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);
423:     }
424:     SNESGetDM(snes,&dm);
425:     DMSNESGetJacobian(dm,&cJ,&ctx);
426:     if (snes->mf_operator) {
427:       PetscViewerASCIIPrintf(viewer,"  Jacobian is applied matrix-free with differencing\n");
428:       pre  = "Preconditioning ";
429:     }
430:     if (cJ == SNESComputeJacobianDefault) {
431:       PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using finite differences one column at a time\n",pre);
432:     } else if (cJ == SNESComputeJacobianDefaultColor) {
433:       PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using finite differences with coloring\n",pre);
434:     /* it slightly breaks data encapsulation for access the DMDA information directly */
435:     } else if (cJ == SNESComputeJacobian_DMDA) {
436:       MatFDColoring fdcoloring;
437:       PetscObjectQuery((PetscObject)dm,"DMDASNES_FDCOLORING",(PetscObject*)&fdcoloring);
438:       if (fdcoloring) {
439:         PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using colored finite differences on a DMDA\n",pre);
440:       } else {
441:         PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using a DMDA local Jacobian\n",pre);
442:       }
443:     } else if (snes->mf) {
444:       PetscViewerASCIIPrintf(viewer,"  Jacobian is applied matrix-free with differencing, no explicit Jacobian\n");
445:     }
446:   } else if (isstring) {
447:     const char *type;
448:     SNESGetType(snes,&type);
449:     PetscViewerStringSPrintf(viewer," SNESType: %-7.7s",type);
450:     if (snes->ops->view) (*snes->ops->view)(snes,viewer);
451:   } else if (isbinary) {
452:     PetscInt    classid = SNES_FILE_CLASSID;
453:     MPI_Comm    comm;
454:     PetscMPIInt rank;
455:     char        type[256];

457:     PetscObjectGetComm((PetscObject)snes,&comm);
458:     MPI_Comm_rank(comm,&rank);
459:     if (rank == 0) {
460:       PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT);
461:       PetscStrncpy(type,((PetscObject)snes)->type_name,sizeof(type));
462:       PetscViewerBinaryWrite(viewer,type,sizeof(type),PETSC_CHAR);
463:     }
464:     if (snes->ops->view) {
465:       (*snes->ops->view)(snes,viewer);
466:     }
467:   } else if (isdraw) {
468:     PetscDraw draw;
469:     char      str[36];
470:     PetscReal x,y,bottom,h;

472:     PetscViewerDrawGetDraw(viewer,0,&draw);
473:     PetscDrawGetCurrentPoint(draw,&x,&y);
474:     PetscStrncpy(str,"SNES: ",sizeof(str));
475:     PetscStrlcat(str,((PetscObject)snes)->type_name,sizeof(str));
476:     PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_BLUE,PETSC_DRAW_BLACK,str,NULL,&h);
477:     bottom = y - h;
478:     PetscDrawPushCurrentPoint(draw,x,bottom);
479:     if (snes->ops->view) {
480:       (*snes->ops->view)(snes,viewer);
481:     }
482: #if defined(PETSC_HAVE_SAWS)
483:   } else if (issaws) {
484:     PetscMPIInt rank;
485:     const char *name;

487:     PetscObjectGetName((PetscObject)snes,&name);
488:     MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
489:     if (!((PetscObject)snes)->amsmem && rank == 0) {
490:       char       dir[1024];

492:       PetscObjectViewSAWs((PetscObject)snes,viewer);
493:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);
494:       PetscStackCallSAWs(SAWs_Register,(dir,&snes->iter,1,SAWs_READ,SAWs_INT));
495:       if (!snes->conv_hist) {
496:         SNESSetConvergenceHistory(snes,NULL,NULL,PETSC_DECIDE,PETSC_TRUE);
497:       }
498:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/conv_hist",name);
499:       PetscStackCallSAWs(SAWs_Register,(dir,snes->conv_hist,10,SAWs_READ,SAWs_DOUBLE));
500:     }
501: #endif
502:   }
503:   if (snes->linesearch) {
504:     SNESGetLineSearch(snes, &linesearch);
505:     PetscViewerASCIIPushTab(viewer);
506:     SNESLineSearchView(linesearch, viewer);
507:     PetscViewerASCIIPopTab(viewer);
508:   }
509:   if (snes->npc && snes->usesnpc) {
510:     PetscViewerASCIIPushTab(viewer);
511:     SNESView(snes->npc, viewer);
512:     PetscViewerASCIIPopTab(viewer);
513:   }
514:   PetscViewerASCIIPushTab(viewer);
515:   DMGetDMSNES(snes->dm,&dmsnes);
516:   DMSNESView(dmsnes, viewer);
517:   PetscViewerASCIIPopTab(viewer);
518:   if (snes->usesksp) {
519:     SNESGetKSP(snes,&ksp);
520:     PetscViewerASCIIPushTab(viewer);
521:     KSPView(ksp,viewer);
522:     PetscViewerASCIIPopTab(viewer);
523:   }
524:   if (isdraw) {
525:     PetscDraw draw;
526:     PetscViewerDrawGetDraw(viewer,0,&draw);
527:     PetscDrawPopCurrentPoint(draw);
528:   }
529:   return 0;
530: }

532: /*
533:   We retain a list of functions that also take SNES command
534:   line options. These are called at the end SNESSetFromOptions()
535: */
536: #define MAXSETFROMOPTIONS 5
537: static PetscInt numberofsetfromoptions;
538: static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);

540: /*@C
541:   SNESAddOptionsChecker - Adds an additional function to check for SNES options.

543:   Not Collective

545:   Input Parameter:
546: . snescheck - function that checks for options

548:   Level: developer

550: .seealso: SNESSetFromOptions()
551: @*/
552: PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
553: {
555:   othersetfromoptions[numberofsetfromoptions++] = snescheck;
556:   return 0;
557: }

559: PETSC_INTERN PetscErrorCode SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);

561: static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
562: {
563:   Mat            J;
564:   MatNullSpace   nullsp;


568:   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
569:     Mat A = snes->jacobian, B = snes->jacobian_pre;
570:     MatCreateVecs(A ? A : B, NULL,&snes->vec_func);
571:   }

573:   if (version == 1) {
574:     MatCreateSNESMF(snes,&J);
575:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
576:     MatSetFromOptions(J);
577:     /* TODO: the version 2 code should be merged into the MatCreateSNESMF() and MatCreateMFFD() infrastructure and then removed */
578:   } else if (version == 2) {
580: #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128) && !defined(PETSC_USE_REAL___FP16)
581:     SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);
582: #else
583:     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator routines (version 2)");
584: #endif
585:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator routines, only version 1 and 2");

587:   /* attach any user provided null space that was on Amat to the newly created matrix free matrix */
588:   if (snes->jacobian) {
589:     MatGetNullSpace(snes->jacobian,&nullsp);
590:     if (nullsp) {
591:       MatSetNullSpace(J,nullsp);
592:     }
593:   }

595:   PetscInfo(snes,"Setting default matrix-free operator routines (version %D)\n", version);
596:   if (hasOperator) {

598:     /* This version replaces the user provided Jacobian matrix with a
599:        matrix-free version but still employs the user-provided preconditioner matrix. */
600:     SNESSetJacobian(snes,J,NULL,NULL,NULL);
601:   } else {
602:     /* This version replaces both the user-provided Jacobian and the user-
603:      provided preconditioner Jacobian with the default matrix free version. */
604:     if (snes->npcside == PC_LEFT && snes->npc) {
605:       if (!snes->jacobian) SNESSetJacobian(snes,J,NULL,NULL,NULL);
606:     } else {
607:       KSP       ksp;
608:       PC        pc;
609:       PetscBool match;

611:       SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,NULL);
612:       /* Force no preconditioner */
613:       SNESGetKSP(snes,&ksp);
614:       KSPGetPC(ksp,&pc);
615:       PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);
616:       if (!match) {
617:         PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");
618:         PCSetType(pc,PCNONE);
619:       }
620:     }
621:   }
622:   MatDestroy(&J);
623:   return 0;
624: }

626: static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
627: {
628:   SNES           snes = (SNES)ctx;
629:   Vec            Xfine,Xfine_named = NULL,Xcoarse;

631:   if (PetscLogPrintInfo) {
632:     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
633:     DMGetRefineLevel(dmfine,&finelevel);
634:     DMGetCoarsenLevel(dmfine,&fineclevel);
635:     DMGetRefineLevel(dmcoarse,&coarselevel);
636:     DMGetCoarsenLevel(dmcoarse,&coarseclevel);
637:     PetscInfo(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);
638:   }
639:   if (dmfine == snes->dm) Xfine = snes->vec_sol;
640:   else {
641:     DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);
642:     Xfine = Xfine_named;
643:   }
644:   DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);
645:   if (Inject) {
646:     MatRestrict(Inject,Xfine,Xcoarse);
647:   } else {
648:     MatRestrict(Restrict,Xfine,Xcoarse);
649:     VecPointwiseMult(Xcoarse,Xcoarse,Rscale);
650:   }
651:   DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);
652:   if (Xfine_named) DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);
653:   return 0;
654: }

656: static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
657: {
658:   DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);
659:   return 0;
660: }

662: /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
663:  * safely call SNESGetDM() in their residual evaluation routine. */
664: static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,void *ctx)
665: {
666:   SNES           snes = (SNES)ctx;
667:   Vec            X,Xnamed = NULL;
668:   DM             dmsave;
669:   void           *ctxsave;
670:   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*) = NULL;

672:   dmsave = snes->dm;
673:   KSPGetDM(ksp,&snes->dm);
674:   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
675:   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
676:     DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);
677:     X    = Xnamed;
678:     SNESGetJacobian(snes,NULL,NULL,&jac,&ctxsave);
679:     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
680:     if (jac == SNESComputeJacobianDefaultColor) {
681:       SNESSetJacobian(snes,NULL,NULL,SNESComputeJacobianDefaultColor,NULL);
682:     }
683:   }
684:   /* Make sure KSP DM has the Jacobian computation routine */
685:   {
686:     DMSNES sdm;

688:     DMGetDMSNES(snes->dm, &sdm);
689:     if (!sdm->ops->computejacobian) {
690:       DMCopyDMSNES(dmsave, snes->dm);
691:     }
692:   }
693:   /* Compute the operators */
694:   SNESComputeJacobian(snes,X,A,B);
695:   /* Put the previous context back */
696:   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) {
697:     SNESSetJacobian(snes,NULL,NULL,jac,ctxsave);
698:   }

700:   if (Xnamed) DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);
701:   snes->dm = dmsave;
702:   return 0;
703: }

705: /*@
706:    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()

708:    Collective

710:    Input Parameter:
711: .  snes - snes to configure

713:    Level: developer

715: .seealso: SNESSetUp()
716: @*/
717: PetscErrorCode SNESSetUpMatrices(SNES snes)
718: {
719:   DM             dm;
720:   DMSNES         sdm;

722:   SNESGetDM(snes,&dm);
723:   DMGetDMSNES(dm,&sdm);
724:   if (!snes->jacobian && snes->mf) {
725:     Mat  J;
726:     void *functx;
727:     MatCreateSNESMF(snes,&J);
728:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
729:     MatSetFromOptions(J);
730:     SNESGetFunction(snes,NULL,NULL,&functx);
731:     SNESSetJacobian(snes,J,J,NULL,NULL);
732:     MatDestroy(&J);
733:   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
734:     Mat J,B;
735:     MatCreateSNESMF(snes,&J);
736:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
737:     MatSetFromOptions(J);
738:     DMCreateMatrix(snes->dm,&B);
739:     /* sdm->computejacobian was already set to reach here */
740:     SNESSetJacobian(snes,J,B,NULL,NULL);
741:     MatDestroy(&J);
742:     MatDestroy(&B);
743:   } else if (!snes->jacobian_pre) {
744:     PetscDS   prob;
745:     Mat       J, B;
746:     PetscBool hasPrec   = PETSC_FALSE;

748:     J    = snes->jacobian;
749:     DMGetDS(dm, &prob);
750:     if (prob) PetscDSHasJacobianPreconditioner(prob, &hasPrec);
751:     if (J)            PetscObjectReference((PetscObject) J);
752:     else if (hasPrec) DMCreateMatrix(snes->dm, &J);
753:     DMCreateMatrix(snes->dm, &B);
754:     SNESSetJacobian(snes, J ? J : B, B, NULL, NULL);
755:     MatDestroy(&J);
756:     MatDestroy(&B);
757:   }
758:   {
759:     KSP ksp;
760:     SNESGetKSP(snes,&ksp);
761:     KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);
762:     DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);
763:   }
764:   return 0;
765: }

767: static PetscErrorCode SNESMonitorPauseFinal_Internal(SNES snes)
768: {
769:   PetscInt       i;

771:   if (!snes->pauseFinal) return 0;
772:   for (i = 0; i < snes->numbermonitors; ++i) {
773:     PetscViewerAndFormat *vf = (PetscViewerAndFormat *) snes->monitorcontext[i];
774:     PetscDraw             draw;
775:     PetscReal             lpause;

777:     if (!vf) continue;
778:     if (vf->lg) {
780:       if (((PetscObject) vf->lg)->classid != PETSC_DRAWLG_CLASSID) continue;
781:       PetscDrawLGGetDraw(vf->lg, &draw);
782:       PetscDrawGetPause(draw, &lpause);
783:       PetscDrawSetPause(draw, -1.0);
784:       PetscDrawPause(draw);
785:       PetscDrawSetPause(draw, lpause);
786:     } else {
787:       PetscBool isdraw;

790:       if (((PetscObject) vf->viewer)->classid != PETSC_VIEWER_CLASSID) continue;
791:       PetscObjectTypeCompare((PetscObject) vf->viewer, PETSCVIEWERDRAW, &isdraw);
792:       if (!isdraw) continue;
793:       PetscViewerDrawGetDraw(vf->viewer, 0, &draw);
794:       PetscDrawGetPause(draw, &lpause);
795:       PetscDrawSetPause(draw, -1.0);
796:       PetscDrawPause(draw);
797:       PetscDrawSetPause(draw, lpause);
798:     }
799:   }
800:   return 0;
801: }

803: /*@C
804:    SNESMonitorSetFromOptions - Sets a monitor function and viewer appropriate for the type indicated by the user

806:    Collective on SNES

808:    Input Parameters:
809: +  snes - SNES object you wish to monitor
810: .  name - the monitor type one is seeking
811: .  help - message indicating what monitoring is done
812: .  manual - manual page for the monitor
813: .  monitor - the monitor function
814: -  monitorsetup - a function that is called once ONLY if the user selected this monitor that may set additional features of the SNES or PetscViewer objects

816:    Level: developer

818: .seealso: PetscOptionsGetViewer(), PetscOptionsGetReal(), PetscOptionsHasName(), PetscOptionsGetString(),
819:           PetscOptionsGetIntArray(), PetscOptionsGetRealArray(), PetscOptionsBool()
820:           PetscOptionsInt(), PetscOptionsString(), PetscOptionsReal(), PetscOptionsBool(),
821:           PetscOptionsName(), PetscOptionsBegin(), PetscOptionsEnd(), PetscOptionsHead(),
822:           PetscOptionsStringArray(),PetscOptionsRealArray(), PetscOptionsScalar(),
823:           PetscOptionsBoolGroupBegin(), PetscOptionsBoolGroup(), PetscOptionsBoolGroupEnd(),
824:           PetscOptionsFList(), PetscOptionsEList()
825: @*/
826: PetscErrorCode  SNESMonitorSetFromOptions(SNES snes,const char name[],const char help[], const char manual[],PetscErrorCode (*monitor)(SNES,PetscInt,PetscReal,PetscViewerAndFormat*),PetscErrorCode (*monitorsetup)(SNES,PetscViewerAndFormat*))
827: {
828:   PetscViewer       viewer;
829:   PetscViewerFormat format;
830:   PetscBool         flg;

832:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,name,&viewer,&format,&flg);
833:   if (flg) {
834:     PetscViewerAndFormat *vf;
835:     PetscViewerAndFormatCreate(viewer,format,&vf);
836:     PetscObjectDereference((PetscObject)viewer);
837:     if (monitorsetup) {
838:       (*monitorsetup)(snes,vf);
839:     }
840:     SNESMonitorSet(snes,(PetscErrorCode (*)(SNES,PetscInt,PetscReal,void*))monitor,vf,(PetscErrorCode (*)(void**))PetscViewerAndFormatDestroy);
841:   }
842:   return 0;
843: }

845: /*@
846:    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.

848:    Collective on SNES

850:    Input Parameter:
851: .  snes - the SNES context

853:    Options Database Keys:
854: +  -snes_type <type> - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, SNESType for complete list
855: .  -snes_stol - convergence tolerance in terms of the norm
856:                 of the change in the solution between steps
857: .  -snes_atol <abstol> - absolute tolerance of residual norm
858: .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
859: .  -snes_divergence_tolerance <divtol> - if the residual goes above divtol*rnorm0, exit with divergence
860: .  -snes_force_iteration <force> - force SNESSolve() to take at least one iteration
861: .  -snes_max_it <max_it> - maximum number of iterations
862: .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
863: .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
864: .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
865: .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
866: .  -snes_lag_preconditioner_persists <true,false> - retains the -snes_lag_preconditioner information across multiple SNESSolve()
867: .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
868: .  -snes_lag_jacobian_persists <true,false> - retains the -snes_lag_jacobian information across multiple SNESSolve()
869: .  -snes_trtol <trtol> - trust region tolerance
870: .  -snes_convergence_test - <default,skip,correct_pressure> convergence test in nonlinear solver.
871:                                default SNESConvergedDefault(). skip SNESConvergedSkip() means continue iterating until max_it or some other criterion is reached, saving expense
872:                                of convergence test. correct_pressure SNESConvergedCorrectPressure() has special handling of a pressure null space.
873: .  -snes_monitor [ascii][:filename][:viewer format] - prints residual norm at each iteration. if no filename given prints to stdout
874: .  -snes_monitor_solution [ascii binary draw][:filename][:viewer format] - plots solution at each iteration
875: .  -snes_monitor_residual [ascii binary draw][:filename][:viewer format] - plots residual (not its norm) at each iteration
876: .  -snes_monitor_solution_update [ascii binary draw][:filename][:viewer format] - plots update to solution at each iteration
877: .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
878: .  -snes_monitor_lg_range - plots residual norm at each iteration
879: .  -snes_monitor_pause_final - Pauses all monitor drawing after the solver ends
880: .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
881: .  -snes_fd_color - use finite differences with coloring to compute Jacobian
882: .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
883: .  -snes_converged_reason - print the reason for convergence/divergence after each solve
884: .  -npc_snes_type <type> - the SNES type to use as a nonlinear preconditioner
885: .   -snes_test_jacobian <optional threshold> - compare the user provided Jacobian with one computed via finite differences to check for errors.  If a threshold is given, display only those entries whose difference is greater than the threshold.
886: -   -snes_test_jacobian_view - display the user provided Jacobian, the finite difference Jacobian and the difference between them to help users detect the location of errors in the user provided Jacobian.

888:     Options Database for Eisenstat-Walker method:
889: +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
890: .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
891: .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
892: .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
893: .  -snes_ksp_ew_gamma <gamma> - Sets gamma
894: .  -snes_ksp_ew_alpha <alpha> - Sets alpha
895: .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
896: -  -snes_ksp_ew_threshold <threshold> - Sets threshold

898:    Notes:
899:    To see all options, run your program with the -help option or consult the users manual

901:    Notes:
902:       SNES supports three approaches for computing (approximate) Jacobians: user provided via SNESSetJacobian(), matrix free, and computing explicitly with
903:       finite differences and coloring using MatFDColoring. It is also possible to use automatic differentiation and the MatFDColoring object.

905:    Level: beginner

907: .seealso: SNESSetOptionsPrefix(), SNESResetFromOptions(), SNES, SNESCreate()
908: @*/
909: PetscErrorCode  SNESSetFromOptions(SNES snes)
910: {
911:   PetscBool      flg,pcset,persist,set;
912:   PetscInt       i,indx,lag,grids;
913:   const char     *deft        = SNESNEWTONLS;
914:   const char     *convtests[] = {"default","skip","correct_pressure"};
915:   SNESKSPEW      *kctx        = NULL;
916:   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
918:   PCSide         pcside;
919:   const char     *optionsprefix;

922:   SNESRegisterAll();
923:   PetscObjectOptionsBegin((PetscObject)snes);
924:   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
925:   PetscOptionsFList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);
926:   if (flg) {
927:     SNESSetType(snes,type);
928:   } else if (!((PetscObject)snes)->type_name) {
929:     SNESSetType(snes,deft);
930:   }
931:   PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,NULL);
932:   PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,NULL);

934:   PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,NULL);
935:   PetscOptionsReal("-snes_divergence_tolerance","Stop if residual norm increases by this factor","SNESSetDivergenceTolerance",snes->divtol,&snes->divtol,NULL);
936:   PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,NULL);
937:   PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,NULL);
938:   PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,NULL);
939:   PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,NULL);
940:   PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,NULL);
941:   PetscOptionsBool("-snes_force_iteration","Force SNESSolve() to take at least one iteration","SNESSetForceIteration",snes->forceiteration,&snes->forceiteration,NULL);
942:   PetscOptionsBool("-snes_check_jacobian_domain_error","Check Jacobian domain error after Jacobian evaluation","SNESCheckJacobianDomainError",snes->checkjacdomainerror,&snes->checkjacdomainerror,NULL);

944:   PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);
945:   if (flg) {
947:     SNESSetLagPreconditioner(snes,lag);
948:   }
949:   PetscOptionsBool("-snes_lag_preconditioner_persists","Preconditioner lagging through multiple SNES solves","SNESSetLagPreconditionerPersists",snes->lagjac_persist,&persist,&flg);
950:   if (flg) {
951:     SNESSetLagPreconditionerPersists(snes,persist);
952:   }
953:   PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);
954:   if (flg) {
956:     SNESSetLagJacobian(snes,lag);
957:   }
958:   PetscOptionsBool("-snes_lag_jacobian_persists","Jacobian lagging through multiple SNES solves","SNESSetLagJacobianPersists",snes->lagjac_persist,&persist,&flg);
959:   if (flg) {
960:     SNESSetLagJacobianPersists(snes,persist);
961:   }

963:   PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);
964:   if (flg) {
965:     SNESSetGridSequence(snes,grids);
966:   }

968:   PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,sizeof(convtests)/sizeof(char*),"default",&indx,&flg);
969:   if (flg) {
970:     switch (indx) {
971:     case 0: SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL); break;
972:     case 1: SNESSetConvergenceTest(snes,SNESConvergedSkip,NULL,NULL); break;
973:     case 2: SNESSetConvergenceTest(snes,SNESConvergedCorrectPressure,NULL,NULL); break;
974:     }
975:   }

977:   PetscOptionsEList("-snes_norm_schedule","SNES Norm schedule","SNESSetNormSchedule",SNESNormSchedules,5,"function",&indx,&flg);
978:   if (flg) SNESSetNormSchedule(snes,(SNESNormSchedule)indx);

980:   PetscOptionsEList("-snes_function_type","SNES Norm schedule","SNESSetFunctionType",SNESFunctionTypes,2,"unpreconditioned",&indx,&flg);
981:   if (flg) SNESSetFunctionType(snes,(SNESFunctionType)indx);

983:   kctx = (SNESKSPEW*)snes->kspconvctx;

985:   PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);

987:   PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,NULL);
988:   PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,NULL);
989:   PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,NULL);
990:   PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,NULL);
991:   PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,NULL);
992:   PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,NULL);
993:   PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,NULL);

995:   flg  = PETSC_FALSE;
996:   PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,&set);
997:   if (set && flg) SNESMonitorCancel(snes);

999:   SNESMonitorSetFromOptions(snes,"-snes_monitor","Monitor norm of function","SNESMonitorDefault",SNESMonitorDefault,SNESMonitorDefaultSetUp);
1000:   SNESMonitorSetFromOptions(snes,"-snes_monitor_short","Monitor norm of function with fewer digits","SNESMonitorDefaultShort",SNESMonitorDefaultShort,NULL);
1001:   SNESMonitorSetFromOptions(snes,"-snes_monitor_range","Monitor range of elements of function","SNESMonitorRange",SNESMonitorRange,NULL);

1003:   SNESMonitorSetFromOptions(snes,"-snes_monitor_ratio","Monitor ratios of the norm of function for consecutive steps","SNESMonitorRatio",SNESMonitorRatio,SNESMonitorRatioSetUp);
1004:   SNESMonitorSetFromOptions(snes,"-snes_monitor_field","Monitor norm of function (split into fields)","SNESMonitorDefaultField",SNESMonitorDefaultField,NULL);
1005:   SNESMonitorSetFromOptions(snes,"-snes_monitor_solution","View solution at each iteration","SNESMonitorSolution",SNESMonitorSolution,NULL);
1006:   SNESMonitorSetFromOptions(snes,"-snes_monitor_solution_update","View correction at each iteration","SNESMonitorSolutionUpdate",SNESMonitorSolutionUpdate,NULL);
1007:   SNESMonitorSetFromOptions(snes,"-snes_monitor_residual","View residual at each iteration","SNESMonitorResidual",SNESMonitorResidual,NULL);
1008:   SNESMonitorSetFromOptions(snes,"-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",SNESMonitorJacUpdateSpectrum,NULL);
1009:   SNESMonitorSetFromOptions(snes,"-snes_monitor_fields","Monitor norm of function per field","SNESMonitorSet",SNESMonitorFields,NULL);
1010:   PetscOptionsBool("-snes_monitor_pause_final", "Pauses all draw monitors at the final iterate", "SNESMonitorPauseFinal_Internal", PETSC_FALSE, &snes->pauseFinal, NULL);

1012:   PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",NULL,monfilename,sizeof(monfilename),&flg);
1013:   if (flg) PetscPythonMonitorSet((PetscObject)snes,monfilename);

1015:   flg  = PETSC_FALSE;
1016:   PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);
1017:   if (flg) {
1018:     PetscViewer ctx;

1020:     PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,400,300,&ctx);
1021:     SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);
1022:   }

1024:   flg  = PETSC_FALSE;
1025:   PetscOptionsBool("-snes_converged_reason_view_cancel","Remove all converged reason viewers","SNESConvergedReasonViewCancel",flg,&flg,&set);
1026:   if (set && flg) SNESConvergedReasonViewCancel(snes);

1028:   flg  = PETSC_FALSE;
1029:   PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);
1030:   if (flg) {
1031:     void    *functx;
1032:     DM      dm;
1033:     DMSNES  sdm;
1034:     SNESGetDM(snes,&dm);
1035:     DMGetDMSNES(dm,&sdm);
1036:     sdm->jacobianctx = NULL;
1037:     SNESGetFunction(snes,NULL,NULL,&functx);
1038:     SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);
1039:     PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");
1040:   }

1042:   flg  = PETSC_FALSE;
1043:   PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);
1044:   if (flg) {
1045:     SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);
1046:   }

1048:   flg  = PETSC_FALSE;
1049:   PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);
1050:   if (flg) {
1051:     DM             dm;
1052:     DMSNES         sdm;
1053:     SNESGetDM(snes,&dm);
1054:     DMGetDMSNES(dm,&sdm);
1055:     sdm->jacobianctx = NULL;
1056:     SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,NULL);
1057:     PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");
1058:   }

1060:   flg  = PETSC_FALSE;
1061:   PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","SNESSetUseMatrixFree",PETSC_FALSE,&snes->mf_operator,&flg);
1062:   if (flg && snes->mf_operator) {
1063:     snes->mf_operator = PETSC_TRUE;
1064:     snes->mf          = PETSC_TRUE;
1065:   }
1066:   flg  = PETSC_FALSE;
1067:   PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","SNESSetUseMatrixFree",PETSC_FALSE,&snes->mf,&flg);
1068:   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
1069:   PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,NULL);

1071:   flg  = PETSC_FALSE;
1072:   SNESGetNPCSide(snes,&pcside);
1073:   PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetNPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);
1074:   if (flg) SNESSetNPCSide(snes,pcside);

1076: #if defined(PETSC_HAVE_SAWS)
1077:   /*
1078:     Publish convergence information using SAWs
1079:   */
1080:   flg  = PETSC_FALSE;
1081:   PetscOptionsBool("-snes_monitor_saws","Publish SNES progress using SAWs","SNESMonitorSet",flg,&flg,NULL);
1082:   if (flg) {
1083:     void *ctx;
1084:     SNESMonitorSAWsCreate(snes,&ctx);
1085:     SNESMonitorSet(snes,SNESMonitorSAWs,ctx,SNESMonitorSAWsDestroy);
1086:   }
1087: #endif
1088: #if defined(PETSC_HAVE_SAWS)
1089:   {
1090:   PetscBool set;
1091:   flg  = PETSC_FALSE;
1092:   PetscOptionsBool("-snes_saws_block","Block for SAWs at end of SNESSolve","PetscObjectSAWsBlock",((PetscObject)snes)->amspublishblock,&flg,&set);
1093:   if (set) {
1094:     PetscObjectSAWsSetBlock((PetscObject)snes,flg);
1095:   }
1096:   }
1097: #endif

1099:   for (i = 0; i < numberofsetfromoptions; i++) {
1100:     (*othersetfromoptions[i])(snes);
1101:   }

1103:   if (snes->ops->setfromoptions) {
1104:     (*snes->ops->setfromoptions)(PetscOptionsObject,snes);
1105:   }

1107:   /* process any options handlers added with PetscObjectAddOptionsHandler() */
1108:   PetscObjectProcessOptionsHandlers(PetscOptionsObject,(PetscObject)snes);
1109:   PetscOptionsEnd();

1111:   if (snes->linesearch) {
1112:     SNESGetLineSearch(snes, &snes->linesearch);
1113:     SNESLineSearchSetFromOptions(snes->linesearch);
1114:   }

1116:   if (snes->usesksp) {
1117:     if (!snes->ksp) SNESGetKSP(snes,&snes->ksp);
1118:     KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);
1119:     KSPSetFromOptions(snes->ksp);
1120:   }

1122:   /* if user has set the SNES NPC type via options database, create it. */
1123:   SNESGetOptionsPrefix(snes, &optionsprefix);
1124:   PetscOptionsHasName(((PetscObject)snes)->options,optionsprefix, "-npc_snes_type", &pcset);
1125:   if (pcset && (!snes->npc)) {
1126:     SNESGetNPC(snes, &snes->npc);
1127:   }
1128:   if (snes->npc) {
1129:     SNESSetFromOptions(snes->npc);
1130:   }
1131:   snes->setfromoptionscalled++;
1132:   return 0;
1133: }

1135: /*@
1136:    SNESResetFromOptions - Sets various SNES and KSP parameters from user options ONLY if the SNES was previously set from options

1138:    Collective on SNES

1140:    Input Parameter:
1141: .  snes - the SNES context

1143:    Level: beginner

1145: .seealso: SNESSetFromOptions(), SNESSetOptionsPrefix()
1146: @*/
1147: PetscErrorCode SNESResetFromOptions(SNES snes)
1148: {
1149:   if (snes->setfromoptionscalled) SNESSetFromOptions(snes);
1150:   return 0;
1151: }

1153: /*@C
1154:    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
1155:    the nonlinear solvers.

1157:    Logically Collective on SNES

1159:    Input Parameters:
1160: +  snes - the SNES context
1161: .  compute - function to compute the context
1162: -  destroy - function to destroy the context

1164:    Level: intermediate

1166:    Notes:
1167:    This function is currently not available from Fortran.

1169: .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
1170: @*/
1171: PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
1172: {
1174:   snes->ops->usercompute = compute;
1175:   snes->ops->userdestroy = destroy;
1176:   return 0;
1177: }

1179: /*@
1180:    SNESSetApplicationContext - Sets the optional user-defined context for
1181:    the nonlinear solvers.

1183:    Logically Collective on SNES

1185:    Input Parameters:
1186: +  snes - the SNES context
1187: -  usrP - optional user context

1189:    Level: intermediate

1191:    Fortran Notes:
1192:     To use this from Fortran you must write a Fortran interface definition for this
1193:     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

1195: .seealso: SNESGetApplicationContext()
1196: @*/
1197: PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
1198: {
1199:   KSP            ksp;

1202:   SNESGetKSP(snes,&ksp);
1203:   KSPSetApplicationContext(ksp,usrP);
1204:   snes->user = usrP;
1205:   return 0;
1206: }

1208: /*@
1209:    SNESGetApplicationContext - Gets the user-defined context for the
1210:    nonlinear solvers.

1212:    Not Collective

1214:    Input Parameter:
1215: .  snes - SNES context

1217:    Output Parameter:
1218: .  usrP - user context

1220:    Fortran Notes:
1221:     To use this from Fortran you must write a Fortran interface definition for this
1222:     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

1224:    Level: intermediate

1226: .seealso: SNESSetApplicationContext()
1227: @*/
1228: PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
1229: {
1231:   *(void**)usrP = snes->user;
1232:   return 0;
1233: }

1235: /*@
1236:    SNESSetUseMatrixFree - indicates that SNES should use matrix free finite difference matrix vector products internally to apply the Jacobian.

1238:    Collective on SNES

1240:    Input Parameters:
1241: +  snes - SNES context
1242: .  mf_operator - use matrix-free only for the Amat used by SNESSetJacobian(), this means the user provided Pmat will continue to be used
1243: -  mf - use matrix-free for both the Amat and Pmat used by SNESSetJacobian(), both the Amat and Pmat set in SNESSetJacobian() will be ignored

1245:    Options Database:
1246: + -snes_mf - use matrix free for both the mat and pmat operator
1247: . -snes_mf_operator - use matrix free only for the mat operator
1248: . -snes_fd_color - compute the Jacobian via coloring and finite differences.
1249: - -snes_fd - compute the Jacobian via finite differences (slow)

1251:    Level: intermediate

1253:    Notes:
1254:       SNES supports three approaches for computing (approximate) Jacobians: user provided via SNESSetJacobian(), matrix free, and computing explicitly with
1255:       finite differences and coloring using MatFDColoring. It is also possible to use automatic differentiation and the MatFDColoring object.

1257: .seealso:   SNESGetUseMatrixFree(), MatCreateSNESMF(), SNESComputeJacobianDefaultColor()
1258: @*/
1259: PetscErrorCode  SNESSetUseMatrixFree(SNES snes,PetscBool mf_operator,PetscBool mf)
1260: {
1264:   snes->mf          = mf_operator ? PETSC_TRUE : mf;
1265:   snes->mf_operator = mf_operator;
1266:   return 0;
1267: }

1269: /*@
1270:    SNESGetUseMatrixFree - indicates if the SNES uses matrix free finite difference matrix vector products to apply the Jacobian.

1272:    Collective on SNES

1274:    Input Parameter:
1275: .  snes - SNES context

1277:    Output Parameters:
1278: +  mf_operator - use matrix-free only for the Amat used by SNESSetJacobian(), this means the user provided Pmat will continue to be used
1279: -  mf - use matrix-free for both the Amat and Pmat used by SNESSetJacobian(), both the Amat and Pmat set in SNESSetJacobian() will be ignored

1281:    Options Database:
1282: + -snes_mf - use matrix free for both the mat and pmat operator
1283: - -snes_mf_operator - use matrix free only for the mat operator

1285:    Level: intermediate

1287: .seealso:   SNESSetUseMatrixFree(), MatCreateSNESMF()
1288: @*/
1289: PetscErrorCode  SNESGetUseMatrixFree(SNES snes,PetscBool *mf_operator,PetscBool *mf)
1290: {
1292:   if (mf)          *mf          = snes->mf;
1293:   if (mf_operator) *mf_operator = snes->mf_operator;
1294:   return 0;
1295: }

1297: /*@
1298:    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
1299:    at this time.

1301:    Not Collective

1303:    Input Parameter:
1304: .  snes - SNES context

1306:    Output Parameter:
1307: .  iter - iteration number

1309:    Notes:
1310:    For example, during the computation of iteration 2 this would return 1.

1312:    This is useful for using lagged Jacobians (where one does not recompute the
1313:    Jacobian at each SNES iteration). For example, the code
1314: .vb
1315:       SNESGetIterationNumber(snes,&it);
1316:       if (!(it % 2)) {
1317:         [compute Jacobian here]
1318:       }
1319: .ve
1320:    can be used in your ComputeJacobian() function to cause the Jacobian to be
1321:    recomputed every second SNES iteration.

1323:    After the SNES solve is complete this will return the number of nonlinear iterations used.

1325:    Level: intermediate

1327: .seealso:   SNESGetLinearSolveIterations()
1328: @*/
1329: PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
1330: {
1333:   *iter = snes->iter;
1334:   return 0;
1335: }

1337: /*@
1338:    SNESSetIterationNumber - Sets the current iteration number.

1340:    Not Collective

1342:    Input Parameters:
1343: +  snes - SNES context
1344: -  iter - iteration number

1346:    Level: developer

1348: .seealso:   SNESGetLinearSolveIterations()
1349: @*/
1350: PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
1351: {
1353:   PetscObjectSAWsTakeAccess((PetscObject)snes);
1354:   snes->iter = iter;
1355:   PetscObjectSAWsGrantAccess((PetscObject)snes);
1356:   return 0;
1357: }

1359: /*@
1360:    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1361:    attempted by the nonlinear solver.

1363:    Not Collective

1365:    Input Parameter:
1366: .  snes - SNES context

1368:    Output Parameter:
1369: .  nfails - number of unsuccessful steps attempted

1371:    Notes:
1372:    This counter is reset to zero for each successive call to SNESSolve().

1374:    Level: intermediate

1376: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1377:           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1378: @*/
1379: PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
1380: {
1383:   *nfails = snes->numFailures;
1384:   return 0;
1385: }

1387: /*@
1388:    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1389:    attempted by the nonlinear solver before it gives up.

1391:    Not Collective

1393:    Input Parameters:
1394: +  snes     - SNES context
1395: -  maxFails - maximum of unsuccessful steps

1397:    Level: intermediate

1399: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1400:           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1401: @*/
1402: PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1403: {
1405:   snes->maxFailures = maxFails;
1406:   return 0;
1407: }

1409: /*@
1410:    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1411:    attempted by the nonlinear solver before it gives up.

1413:    Not Collective

1415:    Input Parameter:
1416: .  snes     - SNES context

1418:    Output Parameter:
1419: .  maxFails - maximum of unsuccessful steps

1421:    Level: intermediate

1423: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1424:           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()

1426: @*/
1427: PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1428: {
1431:   *maxFails = snes->maxFailures;
1432:   return 0;
1433: }

1435: /*@
1436:    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1437:      done by SNES.

1439:    Not Collective

1441:    Input Parameter:
1442: .  snes     - SNES context

1444:    Output Parameter:
1445: .  nfuncs - number of evaluations

1447:    Level: intermediate

1449:    Notes:
1450:     Reset every time SNESSolve is called unless SNESSetCountersReset() is used.

1452: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
1453: @*/
1454: PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1455: {
1458:   *nfuncs = snes->nfuncs;
1459:   return 0;
1460: }

1462: /*@
1463:    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1464:    linear solvers.

1466:    Not Collective

1468:    Input Parameter:
1469: .  snes - SNES context

1471:    Output Parameter:
1472: .  nfails - number of failed solves

1474:    Level: intermediate

1476:    Options Database Keys:
1477: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

1479:    Notes:
1480:    This counter is reset to zero for each successive call to SNESSolve().

1482: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1483: @*/
1484: PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
1485: {
1488:   *nfails = snes->numLinearSolveFailures;
1489:   return 0;
1490: }

1492: /*@
1493:    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1494:    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE

1496:    Logically Collective on SNES

1498:    Input Parameters:
1499: +  snes     - SNES context
1500: -  maxFails - maximum allowed linear solve failures

1502:    Level: intermediate

1504:    Options Database Keys:
1505: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

1507:    Notes:
1508:     By default this is 0; that is SNES returns on the first failed linear solve

1510: .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1511: @*/
1512: PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1513: {
1516:   snes->maxLinearSolveFailures = maxFails;
1517:   return 0;
1518: }

1520: /*@
1521:    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1522:      are allowed before SNES terminates

1524:    Not Collective

1526:    Input Parameter:
1527: .  snes     - SNES context

1529:    Output Parameter:
1530: .  maxFails - maximum of unsuccessful solves allowed

1532:    Level: intermediate

1534:    Notes:
1535:     By default this is 1; that is SNES returns on the first failed linear solve

1537: .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1538: @*/
1539: PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1540: {
1543:   *maxFails = snes->maxLinearSolveFailures;
1544:   return 0;
1545: }

1547: /*@
1548:    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1549:    used by the nonlinear solver.

1551:    Not Collective

1553:    Input Parameter:
1554: .  snes - SNES context

1556:    Output Parameter:
1557: .  lits - number of linear iterations

1559:    Notes:
1560:    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.

1562:    If the linear solver fails inside the SNESSolve() the iterations for that call to the linear solver are not included. If you wish to count them
1563:    then call KSPGetIterationNumber() after the failed solve.

1565:    Level: intermediate

1567: .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
1568: @*/
1569: PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1570: {
1573:   *lits = snes->linear_its;
1574:   return 0;
1575: }

1577: /*@
1578:    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1579:    are reset every time SNESSolve() is called.

1581:    Logically Collective on SNES

1583:    Input Parameters:
1584: +  snes - SNES context
1585: -  reset - whether to reset the counters or not

1587:    Notes:
1588:    This defaults to PETSC_TRUE

1590:    Level: developer

1592: .seealso:  SNESGetNumberFunctionEvals(), SNESGetLinearSolveIterations(), SNESGetNPC()
1593: @*/
1594: PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
1595: {
1598:   snes->counters_reset = reset;
1599:   return 0;
1600: }

1602: /*@
1603:    SNESSetKSP - Sets a KSP context for the SNES object to use

1605:    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm

1607:    Input Parameters:
1608: +  snes - the SNES context
1609: -  ksp - the KSP context

1611:    Notes:
1612:    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1613:    so this routine is rarely needed.

1615:    The KSP object that is already in the SNES object has its reference count
1616:    decreased by one.

1618:    Level: developer

1620: .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1621: @*/
1622: PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1623: {
1627:   PetscObjectReference((PetscObject)ksp);
1628:   if (snes->ksp) PetscObjectDereference((PetscObject)snes->ksp);
1629:   snes->ksp = ksp;
1630:   return 0;
1631: }

1633: /* -----------------------------------------------------------*/
1634: /*@
1635:    SNESCreate - Creates a nonlinear solver context.

1637:    Collective

1639:    Input Parameters:
1640: .  comm - MPI communicator

1642:    Output Parameter:
1643: .  outsnes - the new SNES context

1645:    Options Database Keys:
1646: +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1647:                and no preconditioning matrix
1648: .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1649:                products, and a user-provided preconditioning matrix
1650:                as set by SNESSetJacobian()
1651: -   -snes_fd - Uses (slow!) finite differences to compute Jacobian

1653:    Level: beginner

1655:    Developer Notes:
1656:     SNES always creates a KSP object even though many SNES methods do not use it. This is
1657:                     unfortunate and should be fixed at some point. The flag snes->usesksp indicates if the
1658:                     particular method does use KSP and regulates if the information about the KSP is printed
1659:                     in SNESView(). TSSetFromOptions() does call SNESSetFromOptions() which can lead to users being confused
1660:                     by help messages about meaningless SNES options.

1662:                     SNES always creates the snes->kspconvctx even though it is used by only one type. This should
1663:                     be fixed.

1665: .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner(), SNESSetLagJacobian()

1667: @*/
1668: PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1669: {
1670:   SNES           snes;
1671:   SNESKSPEW      *kctx;

1674:   *outsnes = NULL;
1675:   SNESInitializePackage();

1677:   PetscHeaderCreate(snes,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);

1679:   snes->ops->converged    = SNESConvergedDefault;
1680:   snes->usesksp           = PETSC_TRUE;
1681:   snes->tolerancesset     = PETSC_FALSE;
1682:   snes->max_its           = 50;
1683:   snes->max_funcs         = 10000;
1684:   snes->norm              = 0.0;
1685:   snes->xnorm             = 0.0;
1686:   snes->ynorm             = 0.0;
1687:   snes->normschedule      = SNES_NORM_ALWAYS;
1688:   snes->functype          = SNES_FUNCTION_DEFAULT;
1689: #if defined(PETSC_USE_REAL_SINGLE)
1690:   snes->rtol              = 1.e-5;
1691: #else
1692:   snes->rtol              = 1.e-8;
1693: #endif
1694:   snes->ttol              = 0.0;
1695: #if defined(PETSC_USE_REAL_SINGLE)
1696:   snes->abstol            = 1.e-25;
1697: #else
1698:   snes->abstol            = 1.e-50;
1699: #endif
1700: #if defined(PETSC_USE_REAL_SINGLE)
1701:   snes->stol              = 1.e-5;
1702: #else
1703:   snes->stol              = 1.e-8;
1704: #endif
1705: #if defined(PETSC_USE_REAL_SINGLE)
1706:   snes->deltatol          = 1.e-6;
1707: #else
1708:   snes->deltatol          = 1.e-12;
1709: #endif
1710:   snes->divtol            = 1.e4;
1711:   snes->rnorm0            = 0;
1712:   snes->nfuncs            = 0;
1713:   snes->numFailures       = 0;
1714:   snes->maxFailures       = 1;
1715:   snes->linear_its        = 0;
1716:   snes->lagjacobian       = 1;
1717:   snes->jac_iter          = 0;
1718:   snes->lagjac_persist    = PETSC_FALSE;
1719:   snes->lagpreconditioner = 1;
1720:   snes->pre_iter          = 0;
1721:   snes->lagpre_persist    = PETSC_FALSE;
1722:   snes->numbermonitors    = 0;
1723:   snes->numberreasonviews = 0;
1724:   snes->data              = NULL;
1725:   snes->setupcalled       = PETSC_FALSE;
1726:   snes->ksp_ewconv        = PETSC_FALSE;
1727:   snes->nwork             = 0;
1728:   snes->work              = NULL;
1729:   snes->nvwork            = 0;
1730:   snes->vwork             = NULL;
1731:   snes->conv_hist_len     = 0;
1732:   snes->conv_hist_max     = 0;
1733:   snes->conv_hist         = NULL;
1734:   snes->conv_hist_its     = NULL;
1735:   snes->conv_hist_reset   = PETSC_TRUE;
1736:   snes->counters_reset    = PETSC_TRUE;
1737:   snes->vec_func_init_set = PETSC_FALSE;
1738:   snes->reason            = SNES_CONVERGED_ITERATING;
1739:   snes->npcside           = PC_RIGHT;
1740:   snes->setfromoptionscalled = 0;

1742:   snes->mf          = PETSC_FALSE;
1743:   snes->mf_operator = PETSC_FALSE;
1744:   snes->mf_version  = 1;

1746:   snes->numLinearSolveFailures = 0;
1747:   snes->maxLinearSolveFailures = 1;

1749:   snes->vizerotolerance = 1.e-8;
1750:   snes->checkjacdomainerror = PetscDefined(USE_DEBUG) ? PETSC_TRUE : PETSC_FALSE;

1752:   /* Set this to true if the implementation of SNESSolve_XXX does compute the residual at the final solution. */
1753:   snes->alwayscomputesfinalresidual = PETSC_FALSE;

1755:   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1756:   PetscNewLog(snes,&kctx);

1758:   snes->kspconvctx  = (void*)kctx;
1759:   kctx->version     = 2;
1760:   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1761:                              this was too large for some test cases */
1762:   kctx->rtol_last   = 0.0;
1763:   kctx->rtol_max    = .9;
1764:   kctx->gamma       = 1.0;
1765:   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1766:   kctx->alpha2      = kctx->alpha;
1767:   kctx->threshold   = .1;
1768:   kctx->lresid_last = 0.0;
1769:   kctx->norm_last   = 0.0;

1771:   *outsnes = snes;
1772:   return 0;
1773: }

1775: /*MC
1776:     SNESFunction - Functional form used to convey the nonlinear function to be solved by SNES

1778:      Synopsis:
1779:      #include "petscsnes.h"
1780:      PetscErrorCode SNESFunction(SNES snes,Vec x,Vec f,void *ctx);

1782:      Collective on snes

1784:      Input Parameters:
1785: +     snes - the SNES context
1786: .     x    - state at which to evaluate residual
1787: -     ctx     - optional user-defined function context, passed in with SNESSetFunction()

1789:      Output Parameter:
1790: .     f  - vector to put residual (function value)

1792:    Level: intermediate

1794: .seealso:   SNESSetFunction(), SNESGetFunction()
1795: M*/

1797: /*@C
1798:    SNESSetFunction - Sets the function evaluation routine and function
1799:    vector for use by the SNES routines in solving systems of nonlinear
1800:    equations.

1802:    Logically Collective on SNES

1804:    Input Parameters:
1805: +  snes - the SNES context
1806: .  r - vector to store function values, may be NULL
1807: .  f - function evaluation routine; see SNESFunction for calling sequence details
1808: -  ctx - [optional] user-defined context for private data for the
1809:          function evaluation routine (may be NULL)

1811:    Notes:
1812:    The Newton-like methods typically solve linear systems of the form
1813: $      f'(x) x = -f(x),
1814:    where f'(x) denotes the Jacobian matrix and f(x) is the function.

1816:    Level: beginner

1818: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1819: @*/
1820: PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1821: {
1822:   DM             dm;

1825:   if (r) {
1828:     PetscObjectReference((PetscObject)r);
1829:     VecDestroy(&snes->vec_func);
1830:     snes->vec_func = r;
1831:   }
1832:   SNESGetDM(snes,&dm);
1833:   DMSNESSetFunction(dm,f,ctx);
1834:   if (f == SNESPicardComputeFunction) {
1835:     DMSNESSetMFFunction(dm,SNESPicardComputeMFFunction,ctx);
1836:   }
1837:   return 0;
1838: }

1840: /*@C
1841:    SNESSetInitialFunction - Sets the function vector to be used as the
1842:    function norm at the initialization of the method.  In some
1843:    instances, the user has precomputed the function before calling
1844:    SNESSolve.  This function allows one to avoid a redundant call
1845:    to SNESComputeFunction in that case.

1847:    Logically Collective on SNES

1849:    Input Parameters:
1850: +  snes - the SNES context
1851: -  f - vector to store function value

1853:    Notes:
1854:    This should not be modified during the solution procedure.

1856:    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.

1858:    Level: developer

1860: .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1861: @*/
1862: PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1863: {
1864:   Vec            vec_func;

1869:   if (snes->npcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1870:     snes->vec_func_init_set = PETSC_FALSE;
1871:     return 0;
1872:   }
1873:   SNESGetFunction(snes,&vec_func,NULL,NULL);
1874:   VecCopy(f,vec_func);

1876:   snes->vec_func_init_set = PETSC_TRUE;
1877:   return 0;
1878: }

1880: /*@
1881:    SNESSetNormSchedule - Sets the SNESNormSchedule used in convergence and monitoring
1882:    of the SNES method.

1884:    Logically Collective on SNES

1886:    Input Parameters:
1887: +  snes - the SNES context
1888: -  normschedule - the frequency of norm computation

1890:    Options Database Key:
1891: .  -snes_norm_schedule <none, always, initialonly, finalonly, initialfinalonly> - set the schedule

1893:    Notes:
1894:    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1895:    of the nonlinear function and the taking of its norm at every iteration to
1896:    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1897:    (SNESNGS) and the like do not require the norm of the function to be computed, and therefore
1898:    may either be monitored for convergence or not.  As these are often used as nonlinear
1899:    preconditioners, monitoring the norm of their error is not a useful enterprise within
1900:    their solution.

1902:    Level: developer

1904: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1905: @*/
1906: PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1907: {
1909:   snes->normschedule = normschedule;
1910:   return 0;
1911: }

1913: /*@
1914:    SNESGetNormSchedule - Gets the SNESNormSchedule used in convergence and monitoring
1915:    of the SNES method.

1917:    Logically Collective on SNES

1919:    Input Parameters:
1920: +  snes - the SNES context
1921: -  normschedule - the type of the norm used

1923:    Level: advanced

1925: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1926: @*/
1927: PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1928: {
1930:   *normschedule = snes->normschedule;
1931:   return 0;
1932: }

1934: /*@
1935:   SNESSetFunctionNorm - Sets the last computed residual norm.

1937:   Logically Collective on SNES

1939:   Input Parameters:
1940: + snes - the SNES context

1942: - normschedule - the frequency of norm computation

1944:   Level: developer

1946: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1947: @*/
1948: PetscErrorCode SNESSetFunctionNorm(SNES snes, PetscReal norm)
1949: {
1951:   snes->norm = norm;
1952:   return 0;
1953: }

1955: /*@
1956:   SNESGetFunctionNorm - Gets the last computed norm of the residual

1958:   Not Collective

1960:   Input Parameter:
1961: . snes - the SNES context

1963:   Output Parameter:
1964: . norm - the last computed residual norm

1966:   Level: developer

1968: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1969: @*/
1970: PetscErrorCode SNESGetFunctionNorm(SNES snes, PetscReal *norm)
1971: {
1974:   *norm = snes->norm;
1975:   return 0;
1976: }

1978: /*@
1979:   SNESGetUpdateNorm - Gets the last computed norm of the Newton update

1981:   Not Collective

1983:   Input Parameter:
1984: . snes - the SNES context

1986:   Output Parameter:
1987: . ynorm - the last computed update norm

1989:   Level: developer

1991: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), SNESGetFunctionNorm()
1992: @*/
1993: PetscErrorCode SNESGetUpdateNorm(SNES snes, PetscReal *ynorm)
1994: {
1997:   *ynorm = snes->ynorm;
1998:   return 0;
1999: }

2001: /*@
2002:   SNESGetSolutionNorm - Gets the last computed norm of the solution

2004:   Not Collective

2006:   Input Parameter:
2007: . snes - the SNES context

2009:   Output Parameter:
2010: . xnorm - the last computed solution norm

2012:   Level: developer

2014: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), SNESGetFunctionNorm(), SNESGetUpdateNorm()
2015: @*/
2016: PetscErrorCode SNESGetSolutionNorm(SNES snes, PetscReal *xnorm)
2017: {
2020:   *xnorm = snes->xnorm;
2021:   return 0;
2022: }

2024: /*@C
2025:    SNESSetFunctionType - Sets the SNESNormSchedule used in convergence and monitoring
2026:    of the SNES method.

2028:    Logically Collective on SNES

2030:    Input Parameters:
2031: +  snes - the SNES context
2032: -  normschedule - the frequency of norm computation

2034:    Notes:
2035:    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
2036:    of the nonlinear function and the taking of its norm at every iteration to
2037:    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
2038:    (SNESNGS) and the like do not require the norm of the function to be computed, and therefore
2039:    may either be monitored for convergence or not.  As these are often used as nonlinear
2040:    preconditioners, monitoring the norm of their error is not a useful enterprise within
2041:    their solution.

2043:    Level: developer

2045: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
2046: @*/
2047: PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
2048: {
2050:   snes->functype = type;
2051:   return 0;
2052: }

2054: /*@C
2055:    SNESGetFunctionType - Gets the SNESNormSchedule used in convergence and monitoring
2056:    of the SNES method.

2058:    Logically Collective on SNES

2060:    Input Parameters:
2061: +  snes - the SNES context
2062: -  normschedule - the type of the norm used

2064:    Level: advanced

2066: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
2067: @*/
2068: PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
2069: {
2071:   *type = snes->functype;
2072:   return 0;
2073: }

2075: /*MC
2076:     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function

2078:      Synopsis:
2079: #include <petscsnes.h>
2080: $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);

2082:      Collective on snes

2084:      Input Parameters:
2085: +  X   - solution vector
2086: .  B   - RHS vector
2087: -  ctx - optional user-defined Gauss-Seidel context

2089:      Output Parameter:
2090: .  X   - solution vector

2092:    Level: intermediate

2094: .seealso:   SNESSetNGS(), SNESGetNGS()
2095: M*/

2097: /*@C
2098:    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
2099:    use with composed nonlinear solvers.

2101:    Input Parameters:
2102: +  snes   - the SNES context
2103: .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
2104: -  ctx    - [optional] user-defined context for private data for the
2105:             smoother evaluation routine (may be NULL)

2107:    Notes:
2108:    The NGS routines are used by the composed nonlinear solver to generate
2109:     a problem appropriate update to the solution, particularly FAS.

2111:    Level: intermediate

2113: .seealso: SNESGetFunction(), SNESComputeNGS()
2114: @*/
2115: PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
2116: {
2117:   DM             dm;

2120:   SNESGetDM(snes,&dm);
2121:   DMSNESSetNGS(dm,f,ctx);
2122:   return 0;
2123: }

2125: /*
2126:      This is used for -snes_mf_operator; it uses a duplicate of snes->jacobian_pre because snes->jacobian_pre cannot be
2127:    changed during the KSPSolve()
2128: */
2129: PetscErrorCode SNESPicardComputeMFFunction(SNES snes,Vec x,Vec f,void *ctx)
2130: {
2131:   DM             dm;
2132:   DMSNES         sdm;

2134:   SNESGetDM(snes,&dm);
2135:   DMGetDMSNES(dm,&sdm);
2137:   /*  A(x)*x - b(x) */
2138:   if (sdm->ops->computepfunction) {
2139:     PetscStackPush("SNES Picard user function");
2140:     (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);
2141:     PetscStackPop;
2142:     VecScale(f,-1.0);
2143:     if (!snes->picard) {
2144:       /* Cannot share nonzero pattern because of the possible use of SNESComputeJacobianDefault() */
2145:       MatDuplicate(snes->jacobian_pre,MAT_DO_NOT_COPY_VALUES,&snes->picard);
2146:     }
2147:     PetscStackPush("SNES Picard user Jacobian");
2148:     (*sdm->ops->computepjacobian)(snes,x,snes->picard,snes->picard,sdm->pctx);
2149:     PetscStackPop;
2150:     MatMultAdd(snes->picard,x,f,f);
2151:   } else {
2152:     PetscStackPush("SNES Picard user Jacobian");
2153:     (*sdm->ops->computepjacobian)(snes,x,snes->picard,snes->picard,sdm->pctx);
2154:     PetscStackPop;
2155:     MatMult(snes->picard,x,f);
2156:   }
2157:   return 0;
2158: }

2160: PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
2161: {
2162:   DM             dm;
2163:   DMSNES         sdm;

2165:   SNESGetDM(snes,&dm);
2166:   DMGetDMSNES(dm,&sdm);
2168:   /*  A(x)*x - b(x) */
2169:   if (sdm->ops->computepfunction) {
2170:     PetscStackPush("SNES Picard user function");
2171:     (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);
2172:     PetscStackPop;
2173:     VecScale(f,-1.0);
2174:     PetscStackPush("SNES Picard user Jacobian");
2175:     (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);
2176:     PetscStackPop;
2177:     MatMultAdd(snes->jacobian_pre,x,f,f);
2178:   } else {
2179:     PetscStackPush("SNES Picard user Jacobian");
2180:     (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);
2181:     PetscStackPop;
2182:     MatMult(snes->jacobian_pre,x,f);
2183:   }
2184:   return 0;
2185: }

2187: PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
2188: {
2189:   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
2190:   /* must assembly if matrix-free to get the last SNES solution */
2191:   MatAssemblyBegin(J,MAT_FINAL_ASSEMBLY);
2192:   MatAssemblyEnd(J,MAT_FINAL_ASSEMBLY);
2193:   return 0;
2194: }

2196: /*@C
2197:    SNESSetPicard - Use SNES to solve the system A(x) x = bp(x) + b via a Picard type iteration (Picard linearization)

2199:    Logically Collective on SNES

2201:    Input Parameters:
2202: +  snes - the SNES context
2203: .  r - vector to store function values, may be NULL
2204: .  bp - function evaluation routine, may be NULL
2205: .  Amat - matrix with which A(x) x - bp(x) - b is to be computed
2206: .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
2207: .  J  - function to compute matrix values, see SNESJacobianFunction() for details on its calling sequence
2208: -  ctx - [optional] user-defined context for private data for the function evaluation routine (may be NULL)

2210:    Notes:
2211:     It is often better to provide the nonlinear function F() and some approximation to its Jacobian directly and use
2212:     an approximate Newton solver. This interface is provided to allow porting/testing a previous Picard based code in PETSc before converting it to approximate Newton.

2214:     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both

2216: $     Solves the equation A(x) x = bp(x) - b via the defect correction algorithm A(x^{n}) (x^{n+1} - x^{n}) = bp(x^{n}) + b - A(x^{n})x^{n}
2217: $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = bp(x^{n}) + b iteration.

2219:      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.

2221:    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
2222:    the direct Picard iteration A(x^n) x^{n+1} = bp(x^n) + b

2224:    There is some controversity over the definition of a Picard iteration for nonlinear systems but almost everyone agrees that it involves a linear solve and some
2225:    believe it is the iteration  A(x^{n}) x^{n+1} = b(x^{n}) hence we use the name Picard. If anyone has an authoritative  reference that defines the Picard iteration
2226:    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).

2228:    When used with -snes_mf_operator this will run matrix-free Newton's method where the matrix-vector product is of the true Jacobian of A(x)x - bp(x) -b.

2230:    When used with -snes_fd this will compute the true Jacobian (very slowly one column at at time) and thus represent Newton's method.

2232:    When used with -snes_fd_coloring this will compute the Jacobian via coloring and thus represent a faster implementation of Newton's method. But the
2233:    the nonzero structure of the Jacobian is, in general larger than that of the Picard matrix A so you must provide in A the needed nonzero structure for the correct
2234:    coloring. When using DMDA this may mean creating the matrix A with DMCreateMatrix() using a wider stencil than strictly needed for A or with a DMDA_STENCIL_BOX.
2235:    See the commment in src/snes/tutorials/ex15.c.

2237:    Level: intermediate

2239: .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard(), SNESJacobianFunction
2240: @*/
2241: PetscErrorCode  SNESSetPicard(SNES snes,Vec r,PetscErrorCode (*bp)(SNES,Vec,Vec,void*),Mat Amat, Mat Pmat, PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2242: {
2243:   DM             dm;

2246:   SNESGetDM(snes, &dm);
2247:   DMSNESSetPicard(dm,bp,J,ctx);
2248:   DMSNESSetMFFunction(dm,SNESPicardComputeMFFunction,ctx);
2249:   SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);
2250:   SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);
2251:   return 0;
2252: }

2254: /*@C
2255:    SNESGetPicard - Returns the context for the Picard iteration

2257:    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.

2259:    Input Parameter:
2260: .  snes - the SNES context

2262:    Output Parameters:
2263: +  r - the function (or NULL)
2264: .  f - the function (or NULL); see SNESFunction for calling sequence details
2265: .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
2266: .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
2267: .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
2268: -  ctx - the function context (or NULL)

2270:    Level: advanced

2272: .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
2273: @*/
2274: PetscErrorCode  SNESGetPicard(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),Mat *Amat, Mat *Pmat, PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2275: {
2276:   DM             dm;

2279:   SNESGetFunction(snes,r,NULL,NULL);
2280:   SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);
2281:   SNESGetDM(snes,&dm);
2282:   DMSNESGetPicard(dm,f,J,ctx);
2283:   return 0;
2284: }

2286: /*@C
2287:    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem

2289:    Logically Collective on SNES

2291:    Input Parameters:
2292: +  snes - the SNES context
2293: .  func - function evaluation routine
2294: -  ctx - [optional] user-defined context for private data for the
2295:          function evaluation routine (may be NULL)

2297:    Calling sequence of func:
2298: $    func (SNES snes,Vec x,void *ctx);

2300: .  f - function vector
2301: -  ctx - optional user-defined function context

2303:    Level: intermediate

2305: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
2306: @*/
2307: PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
2308: {
2310:   if (func) snes->ops->computeinitialguess = func;
2311:   if (ctx)  snes->initialguessP            = ctx;
2312:   return 0;
2313: }

2315: /* --------------------------------------------------------------- */
2316: /*@C
2317:    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
2318:    it assumes a zero right hand side.

2320:    Logically Collective on SNES

2322:    Input Parameter:
2323: .  snes - the SNES context

2325:    Output Parameter:
2326: .  rhs - the right hand side vector or NULL if the right hand side vector is null

2328:    Level: intermediate

2330: .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
2331: @*/
2332: PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
2333: {
2336:   *rhs = snes->vec_rhs;
2337:   return 0;
2338: }

2340: /*@
2341:    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().

2343:    Collective on SNES

2345:    Input Parameters:
2346: +  snes - the SNES context
2347: -  x - input vector

2349:    Output Parameter:
2350: .  y - function vector, as set by SNESSetFunction()

2352:    Notes:
2353:    SNESComputeFunction() is typically used within nonlinear solvers
2354:    implementations, so users would not generally call this routine themselves.

2356:    Level: developer

2358: .seealso: SNESSetFunction(), SNESGetFunction(), SNESComputeMFFunction()
2359: @*/
2360: PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2361: {
2362:   DM             dm;
2363:   DMSNES         sdm;

2370:   VecValidValues(x,2,PETSC_TRUE);

2372:   SNESGetDM(snes,&dm);
2373:   DMGetDMSNES(dm,&sdm);
2374:   if (sdm->ops->computefunction) {
2375:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2376:       PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);
2377:     }
2378:     VecLockReadPush(x);
2379:     PetscStackPush("SNES user function");
2380:     /* ensure domainerror is false prior to computefunction evaluation (may not have been reset) */
2381:     snes->domainerror = PETSC_FALSE;
2382:     (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);
2383:     PetscStackPop;
2384:     VecLockReadPop(x);
2385:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2386:       PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);
2387:     }
2388:   } else if (snes->vec_rhs) {
2389:     MatMult(snes->jacobian, x, y);
2390:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2391:   if (snes->vec_rhs) {
2392:     VecAXPY(y,-1.0,snes->vec_rhs);
2393:   }
2394:   snes->nfuncs++;
2395:   /*
2396:      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2397:      propagate the value to all processes
2398:   */
2399:   if (snes->domainerror) {
2400:     VecSetInf(y);
2401:   }
2402:   return 0;
2403: }

2405: /*@
2406:    SNESComputeMFFunction - Calls the function that has been set with SNESSetMFFunction().

2408:    Collective on SNES

2410:    Input Parameters:
2411: +  snes - the SNES context
2412: -  x - input vector

2414:    Output Parameter:
2415: .  y - function vector, as set by SNESSetMFFunction()

2417:    Notes:
2418:        SNESComputeMFFunction() is used within the matrix vector products called by the matrix created with MatCreateSNESMF()
2419:    so users would not generally call this routine themselves.

2421:        Since this function is intended for use with finite differencing it does not subtract the right hand side vector provided with SNESSolve()
2422:     while SNESComputeFunction() does. As such, this routine cannot be used with  MatMFFDSetBase() with a provided F function value even if it applies the
2423:     same function as SNESComputeFunction() if a SNESSolve() right hand side vector is use because the two functions difference would include this right hand side function.

2425:    Level: developer

2427: .seealso: SNESSetFunction(), SNESGetFunction(), SNESComputeFunction(), MatCreateSNESMF
2428: @*/
2429: PetscErrorCode  SNESComputeMFFunction(SNES snes,Vec x,Vec y)
2430: {
2431:   DM             dm;
2432:   DMSNES         sdm;

2439:   VecValidValues(x,2,PETSC_TRUE);

2441:   SNESGetDM(snes,&dm);
2442:   DMGetDMSNES(dm,&sdm);
2443:   PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);
2444:   VecLockReadPush(x);
2445:   PetscStackPush("SNES user function");
2446:   /* ensure domainerror is false prior to computefunction evaluation (may not have been reset) */
2447:   snes->domainerror = PETSC_FALSE;
2448:   (*sdm->ops->computemffunction)(snes,x,y,sdm->mffunctionctx);
2449:   PetscStackPop;
2450:   VecLockReadPop(x);
2451:   PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);
2452:   snes->nfuncs++;
2453:   /*
2454:      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2455:      propagate the value to all processes
2456:   */
2457:   if (snes->domainerror) {
2458:     VecSetInf(y);
2459:   }
2460:   return 0;
2461: }

2463: /*@
2464:    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().

2466:    Collective on SNES

2468:    Input Parameters:
2469: +  snes - the SNES context
2470: .  x - input vector
2471: -  b - rhs vector

2473:    Output Parameter:
2474: .  x - new solution vector

2476:    Notes:
2477:    SNESComputeNGS() is typically used within composed nonlinear solver
2478:    implementations, so most users would not generally call this routine
2479:    themselves.

2481:    Level: developer

2483: .seealso: SNESSetNGS(), SNESComputeFunction()
2484: @*/
2485: PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
2486: {
2487:   DM             dm;
2488:   DMSNES         sdm;

2495:   if (b) VecValidValues(b,2,PETSC_TRUE);
2496:   PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);
2497:   SNESGetDM(snes,&dm);
2498:   DMGetDMSNES(dm,&sdm);
2499:   if (sdm->ops->computegs) {
2500:     if (b) VecLockReadPush(b);
2501:     PetscStackPush("SNES user NGS");
2502:     (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);
2503:     PetscStackPop;
2504:     if (b) VecLockReadPop(b);
2505:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2506:   PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);
2507:   return 0;
2508: }

2510: PetscErrorCode SNESTestJacobian(SNES snes)
2511: {
2512:   Mat               A,B,C,D,jacobian;
2513:   Vec               x = snes->vec_sol,f = snes->vec_func;
2514:   PetscErrorCode    ierr;
2515:   PetscReal         nrm,gnorm;
2516:   PetscReal         threshold = 1.e-5;
2517:   MatType           mattype;
2518:   PetscInt          m,n,M,N;
2519:   void              *functx;
2520:   PetscBool         complete_print = PETSC_FALSE,threshold_print = PETSC_FALSE,test = PETSC_FALSE,flg,istranspose;
2521:   PetscViewer       viewer,mviewer;
2522:   MPI_Comm          comm;
2523:   PetscInt          tabs;
2524:   static PetscBool  directionsprinted = PETSC_FALSE;
2525:   PetscViewerFormat format;

2527:   PetscObjectOptionsBegin((PetscObject)snes);
2528:   PetscOptionsName("-snes_test_jacobian","Compare hand-coded and finite difference Jacobians","None",&test);
2529:   PetscOptionsReal("-snes_test_jacobian", "Threshold for element difference between hand-coded and finite difference being meaningful", "None", threshold, &threshold,NULL);
2530:   PetscOptionsViewer("-snes_test_jacobian_view","View difference between hand-coded and finite difference Jacobians element entries","None",&mviewer,&format,&complete_print);
2531:   if (!complete_print) {
2532:     PetscOptionsDeprecated("-snes_test_jacobian_display","-snes_test_jacobian_view","3.13",NULL);
2533:     PetscOptionsViewer("-snes_test_jacobian_display","Display difference between hand-coded and finite difference Jacobians","None",&mviewer,&format,&complete_print);
2534:   }
2535:   /* for compatibility with PETSc 3.9 and older. */
2536:   PetscOptionsDeprecated("-snes_test_jacobian_display_threshold","-snes_test_jacobian","3.13","-snes_test_jacobian accepts an optional threshold (since v3.10)");
2537:   PetscOptionsReal("-snes_test_jacobian_display_threshold", "Display difference between hand-coded and finite difference Jacobians which exceed input threshold", "None", threshold, &threshold, &threshold_print);
2538:   PetscOptionsEnd();
2539:   if (!test) return 0;

2541:   PetscObjectGetComm((PetscObject)snes,&comm);
2542:   PetscViewerASCIIGetStdout(comm,&viewer);
2543:   PetscViewerASCIIGetTab(viewer, &tabs);
2544:   PetscViewerASCIISetTab(viewer, ((PetscObject)snes)->tablevel);
2545:   PetscViewerASCIIPrintf(viewer,"  ---------- Testing Jacobian -------------\n");
2546:   if (!complete_print && !directionsprinted) {
2547:     PetscViewerASCIIPrintf(viewer,"  Run with -snes_test_jacobian_view and optionally -snes_test_jacobian <threshold> to show difference\n");
2548:     PetscViewerASCIIPrintf(viewer,"    of hand-coded and finite difference Jacobian entries greater than <threshold>.\n");
2549:   }
2550:   if (!directionsprinted) {
2551:     PetscViewerASCIIPrintf(viewer,"  Testing hand-coded Jacobian, if (for double precision runs) ||J - Jfd||_F/||J||_F is\n");
2552:     PetscViewerASCIIPrintf(viewer,"    O(1.e-8), the hand-coded Jacobian is probably correct.\n");
2553:     directionsprinted = PETSC_TRUE;
2554:   }
2555:   if (complete_print) {
2556:     PetscViewerPushFormat(mviewer,format);
2557:   }

2559:   PetscObjectTypeCompare((PetscObject)snes->jacobian,MATMFFD,&flg);
2560:   if (!flg) jacobian = snes->jacobian;
2561:   else jacobian = snes->jacobian_pre;

2563:   if (!x) {
2564:     MatCreateVecs(jacobian, &x, NULL);
2565:   } else {
2566:     PetscObjectReference((PetscObject) x);
2567:   }
2568:   if (!f) {
2569:     VecDuplicate(x, &f);
2570:   } else {
2571:     PetscObjectReference((PetscObject) f);
2572:   }
2573:   /* evaluate the function at this point because SNESComputeJacobianDefault() assumes that the function has been evaluated and put into snes->vec_func */
2574:   SNESComputeFunction(snes,x,f);
2575:   VecDestroy(&f);
2576:   PetscObjectTypeCompare((PetscObject)snes,SNESKSPTRANSPOSEONLY,&istranspose);
2577:   while (jacobian) {
2578:     Mat JT = NULL, Jsave = NULL;

2580:     if (istranspose) {
2581:       MatCreateTranspose(jacobian,&JT);
2582:       Jsave = jacobian;
2583:       jacobian = JT;
2584:     }
2585:     PetscObjectBaseTypeCompareAny((PetscObject)jacobian,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPISBAIJ,"");
2586:     if (flg) {
2587:       A    = jacobian;
2588:       PetscObjectReference((PetscObject)A);
2589:     } else {
2590:       MatComputeOperator(jacobian,MATAIJ,&A);
2591:     }

2593:     MatGetType(A,&mattype);
2594:     MatGetSize(A,&M,&N);
2595:     MatGetLocalSize(A,&m,&n);
2596:     MatCreate(PetscObjectComm((PetscObject)A),&B);
2597:     MatSetType(B,mattype);
2598:     MatSetSizes(B,m,n,M,N);
2599:     MatSetBlockSizesFromMats(B,A,A);
2600:     MatSetUp(B);
2601:     MatSetOption(B,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE);

2603:     SNESGetFunction(snes,NULL,NULL,&functx);
2604:     SNESComputeJacobianDefault(snes,x,B,B,functx);

2606:     MatDuplicate(B,MAT_COPY_VALUES,&D);
2607:     MatAYPX(D,-1.0,A,DIFFERENT_NONZERO_PATTERN);
2608:     MatNorm(D,NORM_FROBENIUS,&nrm);
2609:     MatNorm(A,NORM_FROBENIUS,&gnorm);
2610:     MatDestroy(&D);
2611:     if (!gnorm) gnorm = 1; /* just in case */
2612:     PetscViewerASCIIPrintf(viewer,"  ||J - Jfd||_F/||J||_F = %g, ||J - Jfd||_F = %g\n",(double)(nrm/gnorm),(double)nrm);

2614:     if (complete_print) {
2615:       PetscViewerASCIIPrintf(viewer,"  Hand-coded Jacobian ----------\n");
2616:       MatView(A,mviewer);
2617:       PetscViewerASCIIPrintf(viewer,"  Finite difference Jacobian ----------\n");
2618:       MatView(B,mviewer);
2619:     }

2621:     if (threshold_print || complete_print) {
2622:       PetscInt          Istart, Iend, *ccols, bncols, cncols, j, row;
2623:       PetscScalar       *cvals;
2624:       const PetscInt    *bcols;
2625:       const PetscScalar *bvals;

2627:       MatCreate(PetscObjectComm((PetscObject)A),&C);
2628:       MatSetType(C,mattype);
2629:       MatSetSizes(C,m,n,M,N);
2630:       MatSetBlockSizesFromMats(C,A,A);
2631:       MatSetUp(C);
2632:       MatSetOption(C,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE);

2634:       MatAYPX(B,-1.0,A,DIFFERENT_NONZERO_PATTERN);
2635:       MatGetOwnershipRange(B,&Istart,&Iend);

2637:       for (row = Istart; row < Iend; row++) {
2638:         MatGetRow(B,row,&bncols,&bcols,&bvals);
2639:         PetscMalloc2(bncols,&ccols,bncols,&cvals);
2640:         for (j = 0, cncols = 0; j < bncols; j++) {
2641:           if (PetscAbsScalar(bvals[j]) > threshold) {
2642:             ccols[cncols] = bcols[j];
2643:             cvals[cncols] = bvals[j];
2644:             cncols += 1;
2645:           }
2646:         }
2647:         if (cncols) {
2648:           MatSetValues(C,1,&row,cncols,ccols,cvals,INSERT_VALUES);
2649:         }
2650:         MatRestoreRow(B,row,&bncols,&bcols,&bvals);
2651:         PetscFree2(ccols,cvals);
2652:       }
2653:       MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
2654:       MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
2655:       PetscViewerASCIIPrintf(viewer,"  Hand-coded minus finite-difference Jacobian with tolerance %g ----------\n",(double)threshold);
2656:       MatView(C,complete_print ? mviewer : viewer);
2657:       MatDestroy(&C);
2658:     }
2659:     MatDestroy(&A);
2660:     MatDestroy(&B);
2661:     MatDestroy(&JT);
2662:     if (Jsave) jacobian = Jsave;
2663:     if (jacobian != snes->jacobian_pre) {
2664:       jacobian = snes->jacobian_pre;
2665:       PetscViewerASCIIPrintf(viewer,"  ---------- Testing Jacobian for preconditioner -------------\n");
2666:     }
2667:     else jacobian = NULL;
2668:   }
2669:   VecDestroy(&x);
2670:   if (complete_print) {
2671:     PetscViewerPopFormat(mviewer);
2672:   }
2673:   if (mviewer) PetscViewerDestroy(&mviewer);
2674:   PetscViewerASCIISetTab(viewer,tabs);
2675:   return 0;
2676: }

2678: /*@
2679:    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().

2681:    Collective on SNES

2683:    Input Parameters:
2684: +  snes - the SNES context
2685: -  x - input vector

2687:    Output Parameters:
2688: +  A - Jacobian matrix
2689: -  B - optional preconditioning matrix

2691:   Options Database Keys:
2692: +    -snes_lag_preconditioner <lag> - how often to rebuild preconditioner
2693: .    -snes_lag_jacobian <lag> - how often to rebuild Jacobian
2694: .    -snes_test_jacobian <optional threshold> - compare the user provided Jacobian with one compute via finite differences to check for errors.  If a threshold is given, display only those entries whose difference is greater than the threshold.
2695: .    -snes_test_jacobian_view - display the user provided Jacobian, the finite difference Jacobian and the difference between them to help users detect the location of errors in the user provided Jacobian
2696: .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2697: .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2698: .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2699: .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2700: .    -snes_compare_coloring - Compute the finite difference Jacobian using coloring and display norms of difference
2701: .    -snes_compare_coloring_display - Compute the finite difference Jacobian using coloring and display verbose differences
2702: .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2703: .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2704: .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2705: .    -snes_compare_coloring_draw - Compute the finite difference Jacobian using coloring and draw differences
2706: -    -snes_compare_coloring_draw_contour - Compute the finite difference Jacobian using coloring and show contours of matrices and differences

2708:    Notes:
2709:    Most users should not need to explicitly call this routine, as it
2710:    is used internally within the nonlinear solvers.

2712:    Developer Notes:
2713:     This has duplicative ways of checking the accuracy of the user provided Jacobian (see the options above). This is for historical reasons, the routine SNESTestJacobian() use to used
2714:       for with the SNESType of test that has been removed.

2716:    Level: developer

2718: .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2719: @*/
2720: PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
2721: {
2722:   PetscBool      flag;
2723:   DM             dm;
2724:   DMSNES         sdm;
2725:   KSP            ksp;

2730:   VecValidValues(X,2,PETSC_TRUE);
2731:   SNESGetDM(snes,&dm);
2732:   DMGetDMSNES(dm,&sdm);


2736:   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */

2738:   if (snes->lagjacobian == -2) {
2739:     snes->lagjacobian = -1;

2741:     PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");
2742:   } else if (snes->lagjacobian == -1) {
2743:     PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");
2744:     PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);
2745:     if (flag) {
2746:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
2747:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
2748:     }
2749:     return 0;
2750:   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2751:     PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);
2752:     PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);
2753:     if (flag) {
2754:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
2755:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
2756:     }
2757:     return 0;
2758:   }
2759:   if (snes->npc && snes->npcside == PC_LEFT) {
2760:     MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
2761:     MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
2762:     return 0;
2763:   }

2765:   PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);
2766:   VecLockReadPush(X);
2767:   PetscStackPush("SNES user Jacobian function");
2768:   (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);
2769:   PetscStackPop;
2770:   VecLockReadPop(X);
2771:   PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);

2773:   /* attach latest linearization point to the preconditioning matrix */
2774:   PetscObjectCompose((PetscObject)B,"__SNES_latest_X",(PetscObject)X);

2776:   /* the next line ensures that snes->ksp exists */
2777:   SNESGetKSP(snes,&ksp);
2778:   if (snes->lagpreconditioner == -2) {
2779:     PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");
2780:     KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);
2781:     snes->lagpreconditioner = -1;
2782:   } else if (snes->lagpreconditioner == -1) {
2783:     PetscInfo(snes,"Reusing preconditioner because lag is -1\n");
2784:     KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);
2785:   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2786:     PetscInfo(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);
2787:     KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);
2788:   } else {
2789:     PetscInfo(snes,"Rebuilding preconditioner\n");
2790:     KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);
2791:   }

2793:   SNESTestJacobian(snes);
2794:   /* make sure user returned a correct Jacobian and preconditioner */
2797:   {
2798:     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2799:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit",NULL,NULL,&flag);
2800:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",NULL,NULL,&flag_draw);
2801:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",NULL,NULL,&flag_contour);
2802:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_operator",NULL,NULL,&flag_operator);
2803:     if (flag || flag_draw || flag_contour) {
2804:       Mat          Bexp_mine = NULL,Bexp,FDexp;
2805:       PetscViewer  vdraw,vstdout;
2806:       PetscBool    flg;
2807:       if (flag_operator) {
2808:         MatComputeOperator(A,MATAIJ,&Bexp_mine);
2809:         Bexp = Bexp_mine;
2810:       } else {
2811:         /* See if the preconditioning matrix can be viewed and added directly */
2812:         PetscObjectBaseTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");
2813:         if (flg) Bexp = B;
2814:         else {
2815:           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2816:           MatComputeOperator(B,MATAIJ,&Bexp_mine);
2817:           Bexp = Bexp_mine;
2818:         }
2819:       }
2820:       MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);
2821:       SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);
2822:       PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);
2823:       if (flag_draw || flag_contour) {
2824:         PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),NULL,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);
2825:         if (flag_contour) PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
2826:       } else vdraw = NULL;
2827:       PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");
2828:       if (flag) MatView(Bexp,vstdout);
2829:       if (vdraw) MatView(Bexp,vdraw);
2830:       PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");
2831:       if (flag) MatView(FDexp,vstdout);
2832:       if (vdraw) MatView(FDexp,vdraw);
2833:       MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);
2834:       PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");
2835:       if (flag) MatView(FDexp,vstdout);
2836:       if (vdraw) {              /* Always use contour for the difference */
2837:         PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
2838:         MatView(FDexp,vdraw);
2839:         PetscViewerPopFormat(vdraw);
2840:       }
2841:       if (flag_contour) PetscViewerPopFormat(vdraw);
2842:       PetscViewerDestroy(&vdraw);
2843:       MatDestroy(&Bexp_mine);
2844:       MatDestroy(&FDexp);
2845:     }
2846:   }
2847:   {
2848:     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2849:     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2850:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring",NULL,NULL,&flag);
2851:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_display",NULL,NULL,&flag_display);
2852:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",NULL,NULL,&flag_draw);
2853:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",NULL,NULL,&flag_contour);
2854:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",NULL,NULL,&flag_threshold);
2855:     if (flag_threshold) {
2856:       PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);
2857:       PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);
2858:     }
2859:     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2860:       Mat            Bfd;
2861:       PetscViewer    vdraw,vstdout;
2862:       MatColoring    coloring;
2863:       ISColoring     iscoloring;
2864:       MatFDColoring  matfdcoloring;
2865:       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2866:       void           *funcctx;
2867:       PetscReal      norm1,norm2,normmax;

2869:       MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);
2870:       MatColoringCreate(Bfd,&coloring);
2871:       MatColoringSetType(coloring,MATCOLORINGSL);
2872:       MatColoringSetFromOptions(coloring);
2873:       MatColoringApply(coloring,&iscoloring);
2874:       MatColoringDestroy(&coloring);
2875:       MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);
2876:       MatFDColoringSetFromOptions(matfdcoloring);
2877:       MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);
2878:       ISColoringDestroy(&iscoloring);

2880:       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2881:       SNESGetFunction(snes,NULL,&func,&funcctx);
2882:       MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);
2883:       PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);
2884:       PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");
2885:       MatFDColoringSetFromOptions(matfdcoloring);
2886:       MatFDColoringApply(Bfd,matfdcoloring,X,snes);
2887:       MatFDColoringDestroy(&matfdcoloring);

2889:       PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);
2890:       if (flag_draw || flag_contour) {
2891:         PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),NULL,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);
2892:         if (flag_contour) PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
2893:       } else vdraw = NULL;
2894:       PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");
2895:       if (flag_display) MatView(B,vstdout);
2896:       if (vdraw) MatView(B,vdraw);
2897:       PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");
2898:       if (flag_display) MatView(Bfd,vstdout);
2899:       if (vdraw) MatView(Bfd,vdraw);
2900:       MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);
2901:       MatNorm(Bfd,NORM_1,&norm1);
2902:       MatNorm(Bfd,NORM_FROBENIUS,&norm2);
2903:       MatNorm(Bfd,NORM_MAX,&normmax);
2904:       PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%g normFrob=%g normmax=%g\n",(double)norm1,(double)norm2,(double)normmax);
2905:       if (flag_display) MatView(Bfd,vstdout);
2906:       if (vdraw) {              /* Always use contour for the difference */
2907:         PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
2908:         MatView(Bfd,vdraw);
2909:         PetscViewerPopFormat(vdraw);
2910:       }
2911:       if (flag_contour) PetscViewerPopFormat(vdraw);

2913:       if (flag_threshold) {
2914:         PetscInt bs,rstart,rend,i;
2915:         MatGetBlockSize(B,&bs);
2916:         MatGetOwnershipRange(B,&rstart,&rend);
2917:         for (i=rstart; i<rend; i++) {
2918:           const PetscScalar *ba,*ca;
2919:           const PetscInt    *bj,*cj;
2920:           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2921:           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2922:           MatGetRow(B,i,&bn,&bj,&ba);
2923:           MatGetRow(Bfd,i,&cn,&cj,&ca);
2925:           for (j=0; j<bn; j++) {
2926:             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2927:             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2928:               maxentrycol = bj[j];
2929:               maxentry    = PetscRealPart(ba[j]);
2930:             }
2931:             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2932:               maxdiffcol = bj[j];
2933:               maxdiff    = PetscRealPart(ca[j]);
2934:             }
2935:             if (rdiff > maxrdiff) {
2936:               maxrdiffcol = bj[j];
2937:               maxrdiff    = rdiff;
2938:             }
2939:           }
2940:           if (maxrdiff > 1) {
2941:             PetscViewerASCIIPrintf(vstdout,"row %D (maxentry=%g at %D, maxdiff=%g at %D, maxrdiff=%g at %D):",i,(double)maxentry,maxentrycol,(double)maxdiff,maxdiffcol,(double)maxrdiff,maxrdiffcol);
2942:             for (j=0; j<bn; j++) {
2943:               PetscReal rdiff;
2944:               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2945:               if (rdiff > 1) {
2946:                 PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));
2947:               }
2948:             }
2949:             PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);
2950:           }
2951:           MatRestoreRow(B,i,&bn,&bj,&ba);
2952:           MatRestoreRow(Bfd,i,&cn,&cj,&ca);
2953:         }
2954:       }
2955:       PetscViewerDestroy(&vdraw);
2956:       MatDestroy(&Bfd);
2957:     }
2958:   }
2959:   return 0;
2960: }

2962: /*MC
2963:     SNESJacobianFunction - Function used to convey the nonlinear Jacobian of the function to be solved by SNES

2965:      Synopsis:
2966:      #include "petscsnes.h"
2967:      PetscErrorCode SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);

2969:      Collective on snes

2971:     Input Parameters:
2972: +  x - input vector, the Jacobian is to be computed at this value
2973: -  ctx - [optional] user-defined Jacobian context

2975:     Output Parameters:
2976: +  Amat - the matrix that defines the (approximate) Jacobian
2977: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

2979:    Level: intermediate

2981: .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2982: M*/

2984: /*@C
2985:    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2986:    location to store the matrix.

2988:    Logically Collective on SNES

2990:    Input Parameters:
2991: +  snes - the SNES context
2992: .  Amat - the matrix that defines the (approximate) Jacobian
2993: .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2994: .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value), see SNESJacobianFunction for details
2995: -  ctx - [optional] user-defined context for private data for the
2996:          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)

2998:    Notes:
2999:    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
3000:    each matrix.

3002:    If you know the operator Amat has a null space you can use MatSetNullSpace() and MatSetTransposeNullSpace() to supply the null
3003:    space to Amat and the KSP solvers will automatically use that null space as needed during the solution process.

3005:    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
3006:    must be a MatFDColoring.

3008:    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
3009:    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.

3011:    Level: beginner

3013: .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J,
3014:           SNESSetPicard(), SNESJacobianFunction
3015: @*/
3016: PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
3017: {
3018:   DM             dm;

3025:   SNESGetDM(snes,&dm);
3026:   DMSNESSetJacobian(dm,J,ctx);
3027:   if (Amat) {
3028:     PetscObjectReference((PetscObject)Amat);
3029:     MatDestroy(&snes->jacobian);

3031:     snes->jacobian = Amat;
3032:   }
3033:   if (Pmat) {
3034:     PetscObjectReference((PetscObject)Pmat);
3035:     MatDestroy(&snes->jacobian_pre);

3037:     snes->jacobian_pre = Pmat;
3038:   }
3039:   return 0;
3040: }

3042: /*@C
3043:    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
3044:    provided context for evaluating the Jacobian.

3046:    Not Collective, but Mat object will be parallel if SNES object is

3048:    Input Parameter:
3049: .  snes - the nonlinear solver context

3051:    Output Parameters:
3052: +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
3053: .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
3054: .  J - location to put Jacobian function (or NULL), see SNESJacobianFunction for details on its calling sequence
3055: -  ctx - location to stash Jacobian ctx (or NULL)

3057:    Level: advanced

3059: .seealso: SNESSetJacobian(), SNESComputeJacobian(), SNESJacobianFunction, SNESGetFunction()
3060: @*/
3061: PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
3062: {
3063:   DM             dm;
3064:   DMSNES         sdm;

3067:   if (Amat) *Amat = snes->jacobian;
3068:   if (Pmat) *Pmat = snes->jacobian_pre;
3069:   SNESGetDM(snes,&dm);
3070:   DMGetDMSNES(dm,&sdm);
3071:   if (J) *J = sdm->ops->computejacobian;
3072:   if (ctx) *ctx = sdm->jacobianctx;
3073:   return 0;
3074: }

3076: static PetscErrorCode SNESSetDefaultComputeJacobian(SNES snes)
3077: {
3078:   DM             dm;
3079:   DMSNES         sdm;

3081:   SNESGetDM(snes,&dm);
3082:   DMGetDMSNES(dm,&sdm);
3083:   if (!sdm->ops->computejacobian && snes->jacobian_pre) {
3084:     DM        dm;
3085:     PetscBool isdense,ismf;

3087:     SNESGetDM(snes,&dm);
3088:     PetscObjectTypeCompareAny((PetscObject)snes->jacobian_pre,&isdense,MATSEQDENSE,MATMPIDENSE,MATDENSE,NULL);
3089:     PetscObjectTypeCompareAny((PetscObject)snes->jacobian_pre,&ismf,MATMFFD,MATSHELL,NULL);
3090:     if (isdense) {
3091:       DMSNESSetJacobian(dm,SNESComputeJacobianDefault,NULL);
3092:     } else if (!ismf) {
3093:       DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);
3094:     }
3095:   }
3096:   return 0;
3097: }

3099: /*@
3100:    SNESSetUp - Sets up the internal data structures for the later use
3101:    of a nonlinear solver.

3103:    Collective on SNES

3105:    Input Parameters:
3106: .  snes - the SNES context

3108:    Notes:
3109:    For basic use of the SNES solvers the user need not explicitly call
3110:    SNESSetUp(), since these actions will automatically occur during
3111:    the call to SNESSolve().  However, if one wishes to control this
3112:    phase separately, SNESSetUp() should be called after SNESCreate()
3113:    and optional routines of the form SNESSetXXX(), but before SNESSolve().

3115:    Level: advanced

3117: .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
3118: @*/
3119: PetscErrorCode  SNESSetUp(SNES snes)
3120: {
3121:   DM             dm;
3122:   DMSNES         sdm;
3123:   SNESLineSearch linesearch, pclinesearch;
3124:   void           *lsprectx,*lspostctx;
3125:   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
3126:   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
3127:   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
3128:   Vec            f,fpc;
3129:   void           *funcctx;
3130:   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
3131:   void           *jacctx,*appctx;
3132:   Mat            j,jpre;

3135:   if (snes->setupcalled) return 0;
3136:   PetscLogEventBegin(SNES_Setup,snes,0,0,0);

3138:   if (!((PetscObject)snes)->type_name) {
3139:     SNESSetType(snes,SNESNEWTONLS);
3140:   }

3142:   SNESGetFunction(snes,&snes->vec_func,NULL,NULL);

3144:   SNESGetDM(snes,&dm);
3145:   DMGetDMSNES(dm,&sdm);
3147:   SNESSetDefaultComputeJacobian(snes);

3149:   if (!snes->vec_func) {
3150:     DMCreateGlobalVector(dm,&snes->vec_func);
3151:   }

3153:   if (!snes->ksp) {
3154:     SNESGetKSP(snes, &snes->ksp);
3155:   }

3157:   if (snes->linesearch) {
3158:     SNESGetLineSearch(snes, &snes->linesearch);
3159:     SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);
3160:   }

3162:   if (snes->npc && snes->npcside == PC_LEFT) {
3163:     snes->mf          = PETSC_TRUE;
3164:     snes->mf_operator = PETSC_FALSE;
3165:   }

3167:   if (snes->npc) {
3168:     /* copy the DM over */
3169:     SNESGetDM(snes,&dm);
3170:     SNESSetDM(snes->npc,dm);

3172:     SNESGetFunction(snes,&f,&func,&funcctx);
3173:     VecDuplicate(f,&fpc);
3174:     SNESSetFunction(snes->npc,fpc,func,funcctx);
3175:     SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);
3176:     SNESSetJacobian(snes->npc,j,jpre,jac,jacctx);
3177:     SNESGetApplicationContext(snes,&appctx);
3178:     SNESSetApplicationContext(snes->npc,appctx);
3179:     VecDestroy(&fpc);

3181:     /* copy the function pointers over */
3182:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->npc);

3184:     /* default to 1 iteration */
3185:     SNESSetTolerances(snes->npc,0.0,0.0,0.0,1,snes->npc->max_funcs);
3186:     if (snes->npcside == PC_RIGHT) {
3187:       SNESSetNormSchedule(snes->npc,SNES_NORM_FINAL_ONLY);
3188:     } else {
3189:       SNESSetNormSchedule(snes->npc,SNES_NORM_NONE);
3190:     }
3191:     SNESSetFromOptions(snes->npc);

3193:     /* copy the line search context over */
3194:     if (snes->linesearch && snes->npc->linesearch) {
3195:       SNESGetLineSearch(snes,&linesearch);
3196:       SNESGetLineSearch(snes->npc,&pclinesearch);
3197:       SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
3198:       SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
3199:       SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);
3200:       SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);
3201:       PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);
3202:     }
3203:   }
3204:   if (snes->mf) {
3205:     SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);
3206:   }
3207:   if (snes->ops->usercompute && !snes->user) {
3208:     (*snes->ops->usercompute)(snes,(void**)&snes->user);
3209:   }

3211:   snes->jac_iter = 0;
3212:   snes->pre_iter = 0;

3214:   if (snes->ops->setup) {
3215:     (*snes->ops->setup)(snes);
3216:   }

3218:   SNESSetDefaultComputeJacobian(snes);

3220:   if (snes->npc && snes->npcside == PC_LEFT) {
3221:     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
3222:       if (snes->linesearch) {
3223:         SNESGetLineSearch(snes,&linesearch);
3224:         SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);
3225:       }
3226:     }
3227:   }
3228:   PetscLogEventEnd(SNES_Setup,snes,0,0,0);
3229:   snes->setupcalled = PETSC_TRUE;
3230:   return 0;
3231: }

3233: /*@
3234:    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats

3236:    Collective on SNES

3238:    Input Parameter:
3239: .  snes - iterative context obtained from SNESCreate()

3241:    Level: intermediate

3243:    Notes:
3244:     Also calls the application context destroy routine set with SNESSetComputeApplicationContext()

3246: .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
3247: @*/
3248: PetscErrorCode  SNESReset(SNES snes)
3249: {
3251:   if (snes->ops->userdestroy && snes->user) {
3252:     (*snes->ops->userdestroy)((void**)&snes->user);
3253:     snes->user = NULL;
3254:   }
3255:   if (snes->npc) {
3256:     SNESReset(snes->npc);
3257:   }

3259:   if (snes->ops->reset) {
3260:     (*snes->ops->reset)(snes);
3261:   }
3262:   if (snes->ksp) {
3263:     KSPReset(snes->ksp);
3264:   }

3266:   if (snes->linesearch) {
3267:     SNESLineSearchReset(snes->linesearch);
3268:   }

3270:   VecDestroy(&snes->vec_rhs);
3271:   VecDestroy(&snes->vec_sol);
3272:   VecDestroy(&snes->vec_sol_update);
3273:   VecDestroy(&snes->vec_func);
3274:   MatDestroy(&snes->jacobian);
3275:   MatDestroy(&snes->jacobian_pre);
3276:   MatDestroy(&snes->picard);
3277:   VecDestroyVecs(snes->nwork,&snes->work);
3278:   VecDestroyVecs(snes->nvwork,&snes->vwork);

3280:   snes->alwayscomputesfinalresidual = PETSC_FALSE;

3282:   snes->nwork       = snes->nvwork = 0;
3283:   snes->setupcalled = PETSC_FALSE;
3284:   return 0;
3285: }

3287: /*@
3288:    SNESConvergedReasonViewCancel - Clears all the reasonview functions for a SNES object.

3290:    Collective on SNES

3292:    Input Parameter:
3293: .  snes - iterative context obtained from SNESCreate()

3295:    Level: intermediate

3297: .seealso: SNESCreate(), SNESDestroy(), SNESReset()
3298: @*/
3299: PetscErrorCode  SNESConvergedReasonViewCancel(SNES snes)
3300: {
3301:   PetscInt       i;

3304:   for (i=0; i<snes->numberreasonviews; i++) {
3305:     if (snes->reasonviewdestroy[i]) {
3306:       (*snes->reasonviewdestroy[i])(&snes->reasonviewcontext[i]);
3307:     }
3308:   }
3309:   snes->numberreasonviews = 0;
3310:   return 0;
3311: }

3313: /*@C
3314:    SNESDestroy - Destroys the nonlinear solver context that was created
3315:    with SNESCreate().

3317:    Collective on SNES

3319:    Input Parameter:
3320: .  snes - the SNES context

3322:    Level: beginner

3324: .seealso: SNESCreate(), SNESSolve()
3325: @*/
3326: PetscErrorCode  SNESDestroy(SNES *snes)
3327: {
3328:   if (!*snes) return 0;
3330:   if (--((PetscObject)(*snes))->refct > 0) {*snes = NULL; return 0;}

3332:   SNESReset((*snes));
3333:   SNESDestroy(&(*snes)->npc);

3335:   /* if memory was published with SAWs then destroy it */
3336:   PetscObjectSAWsViewOff((PetscObject)*snes);
3337:   if ((*snes)->ops->destroy) (*((*snes))->ops->destroy)((*snes));

3339:   if ((*snes)->dm) DMCoarsenHookRemove((*snes)->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,*snes);
3340:   DMDestroy(&(*snes)->dm);
3341:   KSPDestroy(&(*snes)->ksp);
3342:   SNESLineSearchDestroy(&(*snes)->linesearch);

3344:   PetscFree((*snes)->kspconvctx);
3345:   if ((*snes)->ops->convergeddestroy) {
3346:     (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);
3347:   }
3348:   if ((*snes)->conv_hist_alloc) {
3349:     PetscFree2((*snes)->conv_hist,(*snes)->conv_hist_its);
3350:   }
3351:   SNESMonitorCancel((*snes));
3352:   SNESConvergedReasonViewCancel((*snes));
3353:   PetscHeaderDestroy(snes);
3354:   return 0;
3355: }

3357: /* ----------- Routines to set solver parameters ---------- */

3359: /*@
3360:    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.

3362:    Logically Collective on SNES

3364:    Input Parameters:
3365: +  snes - the SNES context
3366: -  lag - 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3367:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

3369:    Options Database Keys:
3370: +    -snes_lag_jacobian_persists <true,false> - sets the persistence
3371: .    -snes_lag_jacobian <-2,1,2,...> - sets the lag
3372: .    -snes_lag_preconditioner_persists <true,false> - sets the persistence
3373: -    -snes_lag_preconditioner <-2,1,2,...> - sets the lag

3375:    Notes:
3376:    The default is 1
3377:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1 or SNESSetLagPreconditionerPersists() was called

3379:    SNESSetLagPreconditionerPersists() allows using the same uniform lagging (for example every second solve) across multiple solves.

3381:    Level: intermediate

3383: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetLagPreconditionerPersists(),
3384:           SNESSetLagJacobianPersists()

3386: @*/
3387: PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
3388: {
3393:   snes->lagpreconditioner = lag;
3394:   return 0;
3395: }

3397: /*@
3398:    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does

3400:    Logically Collective on SNES

3402:    Input Parameters:
3403: +  snes - the SNES context
3404: -  steps - the number of refinements to do, defaults to 0

3406:    Options Database Keys:
3407: .    -snes_grid_sequence <steps> - Use grid sequencing to generate initial guess

3409:    Level: intermediate

3411:    Notes:
3412:    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.

3414: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetGridSequence()

3416: @*/
3417: PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
3418: {
3421:   snes->gridsequence = steps;
3422:   return 0;
3423: }

3425: /*@
3426:    SNESGetGridSequence - gets the number of steps of grid sequencing that SNES does

3428:    Logically Collective on SNES

3430:    Input Parameter:
3431: .  snes - the SNES context

3433:    Output Parameter:
3434: .  steps - the number of refinements to do, defaults to 0

3436:    Options Database Keys:
3437: .    -snes_grid_sequence <steps> - set number of refinements

3439:    Level: intermediate

3441:    Notes:
3442:    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.

3444: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetGridSequence()

3446: @*/
3447: PetscErrorCode  SNESGetGridSequence(SNES snes,PetscInt *steps)
3448: {
3450:   *steps = snes->gridsequence;
3451:   return 0;
3452: }

3454: /*@
3455:    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt

3457:    Not Collective

3459:    Input Parameter:
3460: .  snes - the SNES context

3462:    Output Parameter:
3463: .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3464:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

3466:    Options Database Keys:
3467: +    -snes_lag_jacobian_persists <true,false> - sets the persistence
3468: .    -snes_lag_jacobian <-2,1,2,...> - sets the lag
3469: .    -snes_lag_preconditioner_persists <true,false> - sets the persistence
3470: -    -snes_lag_preconditioner <-2,1,2,...> - sets the lag

3472:    Notes:
3473:    The default is 1
3474:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

3476:    Level: intermediate

3478: .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner(), SNESSetLagJacobianPersists(), SNESSetLagPreconditionerPersists()

3480: @*/
3481: PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
3482: {
3484:   *lag = snes->lagpreconditioner;
3485:   return 0;
3486: }

3488: /*@
3489:    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
3490:      often the preconditioner is rebuilt.

3492:    Logically Collective on SNES

3494:    Input Parameters:
3495: +  snes - the SNES context
3496: -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3497:          the Jacobian is built etc. -2 means rebuild at next chance but then never again

3499:    Options Database Keys:
3500: +    -snes_lag_jacobian_persists <true,false> - sets the persistence
3501: .    -snes_lag_jacobian <-2,1,2,...> - sets the lag
3502: .    -snes_lag_preconditioner_persists <true,false> - sets the persistence
3503: -    -snes_lag_preconditioner <-2,1,2,...> - sets the lag.

3505:    Notes:
3506:    The default is 1
3507:    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3508:    If  -1 is used before the very first nonlinear solve the CODE WILL FAIL! because no Jacobian is used, use -2 to indicate you want it recomputed
3509:    at the next Newton step but never again (unless it is reset to another value)

3511:    Level: intermediate

3513: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobianPersists(), SNESSetLagPreconditionerPersists()

3515: @*/
3516: PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
3517: {
3522:   snes->lagjacobian = lag;
3523:   return 0;
3524: }

3526: /*@
3527:    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt

3529:    Not Collective

3531:    Input Parameter:
3532: .  snes - the SNES context

3534:    Output Parameter:
3535: .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3536:          the Jacobian is built etc.

3538:    Notes:
3539:    The default is 1
3540:    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1 or SNESSetLagJacobianPersists() was called.

3542:    Level: intermediate

3544: .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner(), SNESSetLagJacobianPersists(), SNESSetLagPreconditionerPersists()

3546: @*/
3547: PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
3548: {
3550:   *lag = snes->lagjacobian;
3551:   return 0;
3552: }

3554: /*@
3555:    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves

3557:    Logically collective on SNES

3559:    Input Parameters:
3560: +  snes - the SNES context
3561: -   flg - jacobian lagging persists if true

3563:    Options Database Keys:
3564: +    -snes_lag_jacobian_persists <true,false> - sets the persistence
3565: .    -snes_lag_jacobian <-2,1,2,...> - sets the lag
3566: .    -snes_lag_preconditioner_persists <true,false> - sets the persistence
3567: -    -snes_lag_preconditioner <-2,1,2,...> - sets the lag

3569:    Notes:
3570:     This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
3571:    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
3572:    timesteps may present huge efficiency gains.

3574:    Level: developer

3576: .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC(), SNESSetLagJacobianPersists()

3578: @*/
3579: PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
3580: {
3583:   snes->lagjac_persist = flg;
3584:   return 0;
3585: }

3587: /*@
3588:    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple nonlinear solves

3590:    Logically Collective on SNES

3592:    Input Parameters:
3593: +  snes - the SNES context
3594: -   flg - preconditioner lagging persists if true

3596:    Options Database Keys:
3597: +    -snes_lag_jacobian_persists <true,false> - sets the persistence
3598: .    -snes_lag_jacobian <-2,1,2,...> - sets the lag
3599: .    -snes_lag_preconditioner_persists <true,false> - sets the persistence
3600: -    -snes_lag_preconditioner <-2,1,2,...> - sets the lag

3602:    Notes:
3603:     This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
3604:    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
3605:    several timesteps may present huge efficiency gains.

3607:    Level: developer

3609: .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC(), SNESSetLagPreconditioner()

3611: @*/
3612: PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
3613: {
3616:   snes->lagpre_persist = flg;
3617:   return 0;
3618: }

3620: /*@
3621:    SNESSetForceIteration - force SNESSolve() to take at least one iteration regardless of the initial residual norm

3623:    Logically Collective on SNES

3625:    Input Parameters:
3626: +  snes - the SNES context
3627: -  force - PETSC_TRUE require at least one iteration

3629:    Options Database Keys:
3630: .    -snes_force_iteration <force> - Sets forcing an iteration

3632:    Notes:
3633:    This is used sometimes with TS to prevent TS from detecting a false steady state solution

3635:    Level: intermediate

3637: .seealso: SNESSetTrustRegionTolerance(), SNESSetDivergenceTolerance()
3638: @*/
3639: PetscErrorCode  SNESSetForceIteration(SNES snes,PetscBool force)
3640: {
3642:   snes->forceiteration = force;
3643:   return 0;
3644: }

3646: /*@
3647:    SNESGetForceIteration - Whether or not to force SNESSolve() take at least one iteration regardless of the initial residual norm

3649:    Logically Collective on SNES

3651:    Input Parameters:
3652: .  snes - the SNES context

3654:    Output Parameter:
3655: .  force - PETSC_TRUE requires at least one iteration.

3657:    Level: intermediate

3659: .seealso: SNESSetForceIteration(), SNESSetTrustRegionTolerance(), SNESSetDivergenceTolerance()
3660: @*/
3661: PetscErrorCode  SNESGetForceIteration(SNES snes,PetscBool *force)
3662: {
3664:   *force = snes->forceiteration;
3665:   return 0;
3666: }

3668: /*@
3669:    SNESSetTolerances - Sets various parameters used in convergence tests.

3671:    Logically Collective on SNES

3673:    Input Parameters:
3674: +  snes - the SNES context
3675: .  abstol - absolute convergence tolerance
3676: .  rtol - relative convergence tolerance
3677: .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3678: .  maxit - maximum number of iterations
3679: -  maxf - maximum number of function evaluations (-1 indicates no limit)

3681:    Options Database Keys:
3682: +    -snes_atol <abstol> - Sets abstol
3683: .    -snes_rtol <rtol> - Sets rtol
3684: .    -snes_stol <stol> - Sets stol
3685: .    -snes_max_it <maxit> - Sets maxit
3686: -    -snes_max_funcs <maxf> - Sets maxf

3688:    Notes:
3689:    The default maximum number of iterations is 50.
3690:    The default maximum number of function evaluations is 1000.

3692:    Level: intermediate

3694: .seealso: SNESSetTrustRegionTolerance(), SNESSetDivergenceTolerance(), SNESSetForceIteration()
3695: @*/
3696: PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
3697: {

3705:   if (abstol != PETSC_DEFAULT) {
3707:     snes->abstol = abstol;
3708:   }
3709:   if (rtol != PETSC_DEFAULT) {
3711:     snes->rtol = rtol;
3712:   }
3713:   if (stol != PETSC_DEFAULT) {
3715:     snes->stol = stol;
3716:   }
3717:   if (maxit != PETSC_DEFAULT) {
3719:     snes->max_its = maxit;
3720:   }
3721:   if (maxf != PETSC_DEFAULT) {
3723:     snes->max_funcs = maxf;
3724:   }
3725:   snes->tolerancesset = PETSC_TRUE;
3726:   return 0;
3727: }

3729: /*@
3730:    SNESSetDivergenceTolerance - Sets the divergence tolerance used for the SNES divergence test.

3732:    Logically Collective on SNES

3734:    Input Parameters:
3735: +  snes - the SNES context
3736: -  divtol - the divergence tolerance. Use -1 to deactivate the test.

3738:    Options Database Keys:
3739: .    -snes_divergence_tolerance <divtol> - Sets divtol

3741:    Notes:
3742:    The default divergence tolerance is 1e4.

3744:    Level: intermediate

3746: .seealso: SNESSetTolerances(), SNESGetDivergenceTolerance
3747: @*/
3748: PetscErrorCode  SNESSetDivergenceTolerance(SNES snes,PetscReal divtol)
3749: {

3753:   if (divtol != PETSC_DEFAULT) {
3754:     snes->divtol = divtol;
3755:   }
3756:   else {
3757:     snes->divtol = 1.0e4;
3758:   }
3759:   return 0;
3760: }

3762: /*@
3763:    SNESGetTolerances - Gets various parameters used in convergence tests.

3765:    Not Collective

3767:    Input Parameters:
3768: +  snes - the SNES context
3769: .  atol - absolute convergence tolerance
3770: .  rtol - relative convergence tolerance
3771: .  stol -  convergence tolerance in terms of the norm
3772:            of the change in the solution between steps
3773: .  maxit - maximum number of iterations
3774: -  maxf - maximum number of function evaluations

3776:    Notes:
3777:    The user can specify NULL for any parameter that is not needed.

3779:    Level: intermediate

3781: .seealso: SNESSetTolerances()
3782: @*/
3783: PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3784: {
3786:   if (atol)  *atol  = snes->abstol;
3787:   if (rtol)  *rtol  = snes->rtol;
3788:   if (stol)  *stol  = snes->stol;
3789:   if (maxit) *maxit = snes->max_its;
3790:   if (maxf)  *maxf  = snes->max_funcs;
3791:   return 0;
3792: }

3794: /*@
3795:    SNESGetDivergenceTolerance - Gets divergence tolerance used in divergence test.

3797:    Not Collective

3799:    Input Parameters:
3800: +  snes - the SNES context
3801: -  divtol - divergence tolerance

3803:    Level: intermediate

3805: .seealso: SNESSetDivergenceTolerance()
3806: @*/
3807: PetscErrorCode  SNESGetDivergenceTolerance(SNES snes,PetscReal *divtol)
3808: {
3810:   if (divtol) *divtol = snes->divtol;
3811:   return 0;
3812: }

3814: /*@
3815:    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.

3817:    Logically Collective on SNES

3819:    Input Parameters:
3820: +  snes - the SNES context
3821: -  tol - tolerance

3823:    Options Database Key:
3824: .  -snes_trtol <tol> - Sets tol

3826:    Level: intermediate

3828: .seealso: SNESSetTolerances()
3829: @*/
3830: PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3831: {
3834:   snes->deltatol = tol;
3835:   return 0;
3836: }

3838: PETSC_INTERN PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);

3840: PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3841: {
3842:   PetscDrawLG      lg;
3843:   PetscReal        x,y,per;
3844:   PetscViewer      v = (PetscViewer)monctx;
3845:   static PetscReal prev; /* should be in the context */
3846:   PetscDraw        draw;

3849:   PetscViewerDrawGetDrawLG(v,0,&lg);
3850:   if (!n) PetscDrawLGReset(lg);
3851:   PetscDrawLGGetDraw(lg,&draw);
3852:   PetscDrawSetTitle(draw,"Residual norm");
3853:   x    = (PetscReal)n;
3854:   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
3855:   else y = -15.0;
3856:   PetscDrawLGAddPoint(lg,&x,&y);
3857:   if (n < 20 || !(n % 5) || snes->reason) {
3858:     PetscDrawLGDraw(lg);
3859:     PetscDrawLGSave(lg);
3860:   }

3862:   PetscViewerDrawGetDrawLG(v,1,&lg);
3863:   if (!n) PetscDrawLGReset(lg);
3864:   PetscDrawLGGetDraw(lg,&draw);
3865:   PetscDrawSetTitle(draw,"% elemts > .2*max elemt");
3866:   SNESMonitorRange_Private(snes,n,&per);
3867:   x    = (PetscReal)n;
3868:   y    = 100.0*per;
3869:   PetscDrawLGAddPoint(lg,&x,&y);
3870:   if (n < 20 || !(n % 5) || snes->reason) {
3871:     PetscDrawLGDraw(lg);
3872:     PetscDrawLGSave(lg);
3873:   }

3875:   PetscViewerDrawGetDrawLG(v,2,&lg);
3876:   if (!n) {prev = rnorm;PetscDrawLGReset(lg);}
3877:   PetscDrawLGGetDraw(lg,&draw);
3878:   PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");
3879:   x    = (PetscReal)n;
3880:   y    = (prev - rnorm)/prev;
3881:   PetscDrawLGAddPoint(lg,&x,&y);
3882:   if (n < 20 || !(n % 5) || snes->reason) {
3883:     PetscDrawLGDraw(lg);
3884:     PetscDrawLGSave(lg);
3885:   }

3887:   PetscViewerDrawGetDrawLG(v,3,&lg);
3888:   if (!n) PetscDrawLGReset(lg);
3889:   PetscDrawLGGetDraw(lg,&draw);
3890:   PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");
3891:   x    = (PetscReal)n;
3892:   y    = (prev - rnorm)/(prev*per);
3893:   if (n > 2) { /*skip initial crazy value */
3894:     PetscDrawLGAddPoint(lg,&x,&y);
3895:   }
3896:   if (n < 20 || !(n % 5) || snes->reason) {
3897:     PetscDrawLGDraw(lg);
3898:     PetscDrawLGSave(lg);
3899:   }
3900:   prev = rnorm;
3901:   return 0;
3902: }

3904: /*@
3905:    SNESMonitor - runs the user provided monitor routines, if they exist

3907:    Collective on SNES

3909:    Input Parameters:
3910: +  snes - nonlinear solver context obtained from SNESCreate()
3911: .  iter - iteration number
3912: -  rnorm - relative norm of the residual

3914:    Notes:
3915:    This routine is called by the SNES implementations.
3916:    It does not typically need to be called by the user.

3918:    Level: developer

3920: .seealso: SNESMonitorSet()
3921: @*/
3922: PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3923: {
3924:   PetscInt       i,n = snes->numbermonitors;

3926:   VecLockReadPush(snes->vec_sol);
3927:   for (i=0; i<n; i++) {
3928:     (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);
3929:   }
3930:   VecLockReadPop(snes->vec_sol);
3931:   return 0;
3932: }

3934: /* ------------ Routines to set performance monitoring options ----------- */

3936: /*MC
3937:     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver

3939:      Synopsis:
3940: #include <petscsnes.h>
3941: $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)

3943:      Collective on snes

3945:     Input Parameters:
3946: +    snes - the SNES context
3947: .    its - iteration number
3948: .    norm - 2-norm function value (may be estimated)
3949: -    mctx - [optional] monitoring context

3951:    Level: advanced

3953: .seealso:   SNESMonitorSet(), SNESMonitorGet()
3954: M*/

3956: /*@C
3957:    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3958:    iteration of the nonlinear solver to display the iteration's
3959:    progress.

3961:    Logically Collective on SNES

3963:    Input Parameters:
3964: +  snes - the SNES context
3965: .  f - the monitor function, see SNESMonitorFunction for the calling sequence
3966: .  mctx - [optional] user-defined context for private data for the
3967:           monitor routine (use NULL if no context is desired)
3968: -  monitordestroy - [optional] routine that frees monitor context
3969:           (may be NULL)

3971:    Options Database Keys:
3972: +    -snes_monitor        - sets SNESMonitorDefault()
3973: .    -snes_monitor draw::draw_lg - sets line graph monitor,
3974: -    -snes_monitor_cancel - cancels all monitors that have
3975:                             been hardwired into a code by
3976:                             calls to SNESMonitorSet(), but
3977:                             does not cancel those set via
3978:                             the options database.

3980:    Notes:
3981:    Several different monitoring routines may be set by calling
3982:    SNESMonitorSet() multiple times; all will be called in the
3983:    order in which they were set.

3985:    Fortran Notes:
3986:     Only a single monitor function can be set for each SNES object

3988:    Level: intermediate

3990: .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3991: @*/
3992: PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3993: {
3994:   PetscInt       i;
3995:   PetscBool      identical;

3998:   for (i=0; i<snes->numbermonitors;i++) {
3999:     PetscMonitorCompare((PetscErrorCode (*)(void))f,mctx,monitordestroy,(PetscErrorCode (*)(void))snes->monitor[i],snes->monitorcontext[i],snes->monitordestroy[i],&identical);
4000:     if (identical) return 0;
4001:   }
4003:   snes->monitor[snes->numbermonitors]          = f;
4004:   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
4005:   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
4006:   return 0;
4007: }

4009: /*@
4010:    SNESMonitorCancel - Clears all the monitor functions for a SNES object.

4012:    Logically Collective on SNES

4014:    Input Parameters:
4015: .  snes - the SNES context

4017:    Options Database Key:
4018: .  -snes_monitor_cancel - cancels all monitors that have been hardwired
4019:     into a code by calls to SNESMonitorSet(), but does not cancel those
4020:     set via the options database

4022:    Notes:
4023:    There is no way to clear one specific monitor from a SNES object.

4025:    Level: intermediate

4027: .seealso: SNESMonitorDefault(), SNESMonitorSet()
4028: @*/
4029: PetscErrorCode  SNESMonitorCancel(SNES snes)
4030: {
4031:   PetscInt       i;

4034:   for (i=0; i<snes->numbermonitors; i++) {
4035:     if (snes->monitordestroy[i]) {
4036:       (*snes->monitordestroy[i])(&snes->monitorcontext[i]);
4037:     }
4038:   }
4039:   snes->numbermonitors = 0;
4040:   return 0;
4041: }

4043: /*MC
4044:     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver

4046:      Synopsis:
4047: #include <petscsnes.h>
4048: $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)

4050:      Collective on snes

4052:     Input Parameters:
4053: +    snes - the SNES context
4054: .    it - current iteration (0 is the first and is before any Newton step)
4055: .    xnorm - 2-norm of current iterate
4056: .    gnorm - 2-norm of current step
4057: .    f - 2-norm of function
4058: -    cctx - [optional] convergence context

4060:     Output Parameter:
4061: .    reason - reason for convergence/divergence, only needs to be set when convergence or divergence is detected

4063:    Level: intermediate

4065: .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
4066: M*/

4068: /*@C
4069:    SNESSetConvergenceTest - Sets the function that is to be used
4070:    to test for convergence of the nonlinear iterative solution.

4072:    Logically Collective on SNES

4074:    Input Parameters:
4075: +  snes - the SNES context
4076: .  SNESConvergenceTestFunction - routine to test for convergence
4077: .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
4078: -  destroy - [optional] destructor for the context (may be NULL; PETSC_NULL_FUNCTION in Fortran)

4080:    Level: advanced

4082: .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
4083: @*/
4084: PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
4085: {
4087:   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
4088:   if (snes->ops->convergeddestroy) {
4089:     (*snes->ops->convergeddestroy)(snes->cnvP);
4090:   }
4091:   snes->ops->converged        = SNESConvergenceTestFunction;
4092:   snes->ops->convergeddestroy = destroy;
4093:   snes->cnvP                  = cctx;
4094:   return 0;
4095: }

4097: /*@
4098:    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.

4100:    Not Collective

4102:    Input Parameter:
4103: .  snes - the SNES context

4105:    Output Parameter:
4106: .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
4107:             manual pages for the individual convergence tests for complete lists

4109:    Options Database:
4110: .   -snes_converged_reason - prints the reason to standard out

4112:    Level: intermediate

4114:    Notes:
4115:     Should only be called after the call the SNESSolve() is complete, if it is called earlier it returns the value SNES__CONVERGED_ITERATING.

4117: .seealso: SNESSetConvergenceTest(), SNESSetConvergedReason(), SNESConvergedReason
4118: @*/
4119: PetscErrorCode SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
4120: {
4123:   *reason = snes->reason;
4124:   return 0;
4125: }

4127: /*@C
4128:    SNESGetConvergedReasonString - Return a human readable string for snes converged reason

4130:    Not Collective

4132:    Input Parameter:
4133: .  snes - the SNES context

4135:    Output Parameter:
4136: .  strreason - a human readable string that describes SNES converged reason

4138:    Level: beginner

4140: .seealso: SNESGetConvergedReason()
4141: @*/
4142: PetscErrorCode SNESGetConvergedReasonString(SNES snes, const char** strreason)
4143: {
4146:   *strreason = SNESConvergedReasons[snes->reason];
4147:   return 0;
4148: }

4150: /*@
4151:    SNESSetConvergedReason - Sets the reason the SNES iteration was stopped.

4153:    Not Collective

4155:    Input Parameters:
4156: +  snes - the SNES context
4157: -  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
4158:             manual pages for the individual convergence tests for complete lists

4160:    Level: intermediate

4162: .seealso: SNESGetConvergedReason(), SNESSetConvergenceTest(), SNESConvergedReason
4163: @*/
4164: PetscErrorCode SNESSetConvergedReason(SNES snes,SNESConvergedReason reason)
4165: {
4167:   snes->reason = reason;
4168:   return 0;
4169: }

4171: /*@
4172:    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.

4174:    Logically Collective on SNES

4176:    Input Parameters:
4177: +  snes - iterative context obtained from SNESCreate()
4178: .  a   - array to hold history, this array will contain the function norms computed at each step
4179: .  its - integer array holds the number of linear iterations for each solve.
4180: .  na  - size of a and its
4181: -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
4182:            else it continues storing new values for new nonlinear solves after the old ones

4184:    Notes:
4185:    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
4186:    default array of length 10000 is allocated.

4188:    This routine is useful, e.g., when running a code for purposes
4189:    of accurate performance monitoring, when no I/O should be done
4190:    during the section of code that is being timed.

4192:    Level: intermediate

4194: .seealso: SNESGetConvergenceHistory()

4196: @*/
4197: PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
4198: {
4202:   if (!a) {
4203:     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
4204:     PetscCalloc2(na,&a,na,&its);
4205:     snes->conv_hist_alloc = PETSC_TRUE;
4206:   }
4207:   snes->conv_hist       = a;
4208:   snes->conv_hist_its   = its;
4209:   snes->conv_hist_max   = (size_t)na;
4210:   snes->conv_hist_len   = 0;
4211:   snes->conv_hist_reset = reset;
4212:   return 0;
4213: }

4215: #if defined(PETSC_HAVE_MATLAB_ENGINE)
4216: #include <engine.h>   /* MATLAB include file */
4217: #include <mex.h>      /* MATLAB include file */

4219: PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
4220: {
4221:   mxArray   *mat;
4222:   PetscInt  i;
4223:   PetscReal *ar;

4225:   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
4226:   ar  = (PetscReal*) mxGetData(mat);
4227:   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
4228:   return mat;
4229: }
4230: #endif

4232: /*@C
4233:    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.

4235:    Not Collective

4237:    Input Parameter:
4238: .  snes - iterative context obtained from SNESCreate()

4240:    Output Parameters:
4241: +  a   - array to hold history
4242: .  its - integer array holds the number of linear iterations (or
4243:          negative if not converged) for each solve.
4244: -  na  - size of a and its

4246:    Notes:
4247:     The calling sequence for this routine in Fortran is
4248: $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)

4250:    This routine is useful, e.g., when running a code for purposes
4251:    of accurate performance monitoring, when no I/O should be done
4252:    during the section of code that is being timed.

4254:    Level: intermediate

4256: .seealso: SNESSetConvergenceHistory()

4258: @*/
4259: PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
4260: {
4262:   if (a)   *a   = snes->conv_hist;
4263:   if (its) *its = snes->conv_hist_its;
4264:   if (na)  *na  = (PetscInt) snes->conv_hist_len;
4265:   return 0;
4266: }

4268: /*@C
4269:   SNESSetUpdate - Sets the general-purpose update function called
4270:   at the beginning of every iteration of the nonlinear solve. Specifically
4271:   it is called just before the Jacobian is "evaluated".

4273:   Logically Collective on SNES

4275:   Input Parameters:
4276: + snes - The nonlinear solver context
4277: - func - The function

4279:   Calling sequence of func:
4280: $ func (SNES snes, PetscInt step);

4282: . step - The current step of the iteration

4284:   Level: advanced

4286:   Note:
4287:      This is NOT what one uses to update the ghost points before a function evaluation, that should be done at the beginning of your FormFunction()
4288:      This is not used by most users.

4290:      There are a varity of function hooks one many set that are called at different stages of the nonlinear solution process, see the functions listed below.

4292: .seealso SNESSetJacobian(), SNESSolve(), SNESLineSearchSetPreCheck(), SNESLineSearchSetPostCheck(), SNESNewtonTRSetPreCheck(), SNESNewtonTRSetPostCheck(),
4293:          SNESMonitorSet(), SNESSetDivergenceTest()
4294: @*/
4295: PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
4296: {
4298:   snes->ops->update = func;
4299:   return 0;
4300: }

4302: /*
4303:    SNESScaleStep_Private - Scales a step so that its length is less than the
4304:    positive parameter delta.

4306:     Input Parameters:
4307: +   snes - the SNES context
4308: .   y - approximate solution of linear system
4309: .   fnorm - 2-norm of current function
4310: -   delta - trust region size

4312:     Output Parameters:
4313: +   gpnorm - predicted function norm at the new point, assuming local
4314:     linearization.  The value is zero if the step lies within the trust
4315:     region, and exceeds zero otherwise.
4316: -   ynorm - 2-norm of the step

4318:     Note:
4319:     For non-trust region methods such as SNESNEWTONLS, the parameter delta
4320:     is set to be the maximum allowable step size.

4322: */
4323: PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
4324: {
4325:   PetscReal      nrm;
4326:   PetscScalar    cnorm;


4332:   VecNorm(y,NORM_2,&nrm);
4333:   if (nrm > *delta) {
4334:     nrm     = *delta/nrm;
4335:     *gpnorm = (1.0 - nrm)*(*fnorm);
4336:     cnorm   = nrm;
4337:     VecScale(y,cnorm);
4338:     *ynorm  = *delta;
4339:   } else {
4340:     *gpnorm = 0.0;
4341:     *ynorm  = nrm;
4342:   }
4343:   return 0;
4344: }

4346: /*@C
4347:    SNESConvergedReasonView - Displays the reason a SNES solve converged or diverged to a viewer

4349:    Collective on SNES

4351:    Parameter:
4352: +  snes - iterative context obtained from SNESCreate()
4353: -  viewer - the viewer to display the reason

4355:    Options Database Keys:
4356: +  -snes_converged_reason - print reason for converged or diverged, also prints number of iterations
4357: -  -snes_converged_reason ::failed - only print reason and number of iterations when diverged

4359:   Notes:
4360:      To change the format of the output call PetscViewerPushFormat(viewer,format) before this call. Use PETSC_VIEWER_DEFAULT for the default,
4361:      use PETSC_VIEWER_FAILED to only display a reason if it fails.

4363:    Level: beginner

4365: .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault(), SNESGetConvergedReason(), SNESConvergedReasonViewFromOptions(),
4366:           PetscViewerPushFormat(), PetscViewerPopFormat()

4368: @*/
4369: PetscErrorCode  SNESConvergedReasonView(SNES snes,PetscViewer viewer)
4370: {
4371:   PetscViewerFormat format;
4372:   PetscBool         isAscii;

4374:   if (!viewer) viewer = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes));
4375:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isAscii);
4376:   if (isAscii) {
4377:     PetscViewerGetFormat(viewer, &format);
4378:     PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);
4379:     if (format == PETSC_VIEWER_ASCII_INFO_DETAIL) {
4380:       DM              dm;
4381:       Vec             u;
4382:       PetscDS         prob;
4383:       PetscInt        Nf, f;
4384:       PetscErrorCode (**exactSol)(PetscInt, PetscReal, const PetscReal[], PetscInt, PetscScalar[], void *);
4385:       void            **exactCtx;
4386:       PetscReal       error;

4388:       SNESGetDM(snes, &dm);
4389:       SNESGetSolution(snes, &u);
4390:       DMGetDS(dm, &prob);
4391:       PetscDSGetNumFields(prob, &Nf);
4392:       PetscMalloc2(Nf, &exactSol, Nf, &exactCtx);
4393:       for (f = 0; f < Nf; ++f) PetscDSGetExactSolution(prob, f, &exactSol[f], &exactCtx[f]);
4394:       DMComputeL2Diff(dm, 0.0, exactSol, exactCtx, u, &error);
4395:       PetscFree2(exactSol, exactCtx);
4396:       if (error < 1.0e-11) PetscViewerASCIIPrintf(viewer, "L_2 Error: < 1.0e-11\n");
4397:       else                 PetscViewerASCIIPrintf(viewer, "L_2 Error: %g\n", error);
4398:     }
4399:     if (snes->reason > 0 && format != PETSC_VIEWER_FAILED) {
4400:       if (((PetscObject) snes)->prefix) {
4401:         PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve converged due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);
4402:       } else {
4403:         PetscViewerASCIIPrintf(viewer,"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);
4404:       }
4405:     } else if (snes->reason <= 0) {
4406:       if (((PetscObject) snes)->prefix) {
4407:         PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve did not converge due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);
4408:       } else {
4409:         PetscViewerASCIIPrintf(viewer,"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);
4410:       }
4411:     }
4412:     PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);
4413:   }
4414:   return 0;
4415: }

4417: /*@C
4418:    SNESConvergedReasonViewSet - Sets an ADDITIONAL function that is to be used at the
4419:     end of the nonlinear solver to display the conver reason of the nonlinear solver.

4421:    Logically Collective on SNES

4423:    Input Parameters:
4424: +  snes - the SNES context
4425: .  f - the snes converged reason view function
4426: .  vctx - [optional] user-defined context for private data for the
4427:           snes converged reason view routine (use NULL if no context is desired)
4428: -  reasonviewdestroy - [optional] routine that frees reasonview context
4429:           (may be NULL)

4431:    Options Database Keys:
4432: +    -snes_converged_reason        - sets a default SNESConvergedReasonView()
4433: -    -snes_converged_reason_view_cancel - cancels all converged reason viewers that have
4434:                             been hardwired into a code by
4435:                             calls to SNESConvergedReasonViewSet(), but
4436:                             does not cancel those set via
4437:                             the options database.

4439:    Notes:
4440:    Several different converged reason view routines may be set by calling
4441:    SNESConvergedReasonViewSet() multiple times; all will be called in the
4442:    order in which they were set.

4444:    Level: intermediate

4446: .seealso: SNESConvergedReasonView(), SNESConvergedReasonViewCancel()
4447: @*/
4448: PetscErrorCode  SNESConvergedReasonViewSet(SNES snes,PetscErrorCode (*f)(SNES,void*),void *vctx,PetscErrorCode (*reasonviewdestroy)(void**))
4449: {
4450:   PetscInt       i;
4451:   PetscBool      identical;

4454:   for (i=0; i<snes->numberreasonviews;i++) {
4455:     PetscMonitorCompare((PetscErrorCode (*)(void))f,vctx,reasonviewdestroy,(PetscErrorCode (*)(void))snes->reasonview[i],snes->reasonviewcontext[i],snes->reasonviewdestroy[i],&identical);
4456:     if (identical) return 0;
4457:   }
4459:   snes->reasonview[snes->numberreasonviews]          = f;
4460:   snes->reasonviewdestroy[snes->numberreasonviews]   = reasonviewdestroy;
4461:   snes->reasonviewcontext[snes->numberreasonviews++] = (void*)vctx;
4462:   return 0;
4463: }

4465: /*@
4466:   SNESConvergedReasonViewFromOptions - Processes command line options to determine if/how a SNESReason is to be viewed.
4467:                                        All the user-provided convergedReasonView routines will be involved as well, if they exist.

4469:   Collective on SNES

4471:   Input Parameters:
4472: . snes   - the SNES object

4474:   Level: intermediate

4476: .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault(), SNESGetConvergedReason(), SNESConvergedReasonView()

4478: @*/
4479: PetscErrorCode SNESConvergedReasonViewFromOptions(SNES snes)
4480: {
4481:   PetscViewer       viewer;
4482:   PetscBool         flg;
4483:   static PetscBool  incall = PETSC_FALSE;
4484:   PetscViewerFormat format;
4485:   PetscInt          i;

4487:   if (incall) return 0;
4488:   incall = PETSC_TRUE;

4490:   /* All user-provided viewers are called first, if they exist. */
4491:   for (i=0; i<snes->numberreasonviews; i++) {
4492:     (*snes->reasonview[i])(snes,snes->reasonviewcontext[i]);
4493:   }

4495:   /* Call PETSc default routine if users ask for it */
4496:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_converged_reason",&viewer,&format,&flg);
4497:   if (flg) {
4498:     PetscViewerPushFormat(viewer,format);
4499:     SNESConvergedReasonView(snes,viewer);
4500:     PetscViewerPopFormat(viewer);
4501:     PetscViewerDestroy(&viewer);
4502:   }
4503:   incall = PETSC_FALSE;
4504:   return 0;
4505: }

4507: /*@
4508:    SNESSolve - Solves a nonlinear system F(x) = b.
4509:    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().

4511:    Collective on SNES

4513:    Input Parameters:
4514: +  snes - the SNES context
4515: .  b - the constant part of the equation F(x) = b, or NULL to use zero.
4516: -  x - the solution vector.

4518:    Notes:
4519:    The user should initialize the vector,x, with the initial guess
4520:    for the nonlinear solve prior to calling SNESSolve().  In particular,
4521:    to employ an initial guess of zero, the user should explicitly set
4522:    this vector to zero by calling VecSet().

4524:    Level: beginner

4526: .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution(),
4527:           SNESNewtonTRSetPreCheck(), SNESNewtonTRGetPreCheck(), SNESNewtonTRSetPostCheck(), SNESNewtonTRGetPostCheck(),
4528:           SNESLineSearchSetPostCheck(), SNESLineSearchGetPostCheck(), SNESLineSearchSetPreCheck(), SNESLineSearchGetPreCheck()
4529: @*/
4530: PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
4531: {
4532:   PetscBool         flg;
4533:   PetscInt          grid;
4534:   Vec               xcreated = NULL;
4535:   DM                dm;


4543:   /* High level operations using the nonlinear solver */
4544:   {
4545:     PetscViewer       viewer;
4546:     PetscViewerFormat format;
4547:     PetscInt          num;
4548:     PetscBool         flg;
4549:     static PetscBool  incall = PETSC_FALSE;

4551:     if (!incall) {
4552:       /* Estimate the convergence rate of the discretization */
4553:       PetscOptionsGetViewer(PetscObjectComm((PetscObject) snes),((PetscObject)snes)->options, ((PetscObject) snes)->prefix, "-snes_convergence_estimate", &viewer, &format, &flg);
4554:       if (flg) {
4555:         PetscConvEst conv;
4556:         DM           dm;
4557:         PetscReal   *alpha; /* Convergence rate of the solution error for each field in the L_2 norm */
4558:         PetscInt     Nf;

4560:         incall = PETSC_TRUE;
4561:         SNESGetDM(snes, &dm);
4562:         DMGetNumFields(dm, &Nf);
4563:         PetscCalloc1(Nf, &alpha);
4564:         PetscConvEstCreate(PetscObjectComm((PetscObject) snes), &conv);
4565:         PetscConvEstSetSolver(conv, (PetscObject) snes);
4566:         PetscConvEstSetFromOptions(conv);
4567:         PetscConvEstSetUp(conv);
4568:         PetscConvEstGetConvRate(conv, alpha);
4569:         PetscViewerPushFormat(viewer, format);
4570:         PetscConvEstRateView(conv, alpha, viewer);
4571:         PetscViewerPopFormat(viewer);
4572:         PetscViewerDestroy(&viewer);
4573:         PetscConvEstDestroy(&conv);
4574:         PetscFree(alpha);
4575:         incall = PETSC_FALSE;
4576:       }
4577:       /* Adaptively refine the initial grid */
4578:       num  = 1;
4579:       PetscOptionsGetInt(NULL, ((PetscObject) snes)->prefix, "-snes_adapt_initial", &num, &flg);
4580:       if (flg) {
4581:         DMAdaptor adaptor;

4583:         incall = PETSC_TRUE;
4584:         DMAdaptorCreate(PetscObjectComm((PetscObject)snes), &adaptor);
4585:         DMAdaptorSetSolver(adaptor, snes);
4586:         DMAdaptorSetSequenceLength(adaptor, num);
4587:         DMAdaptorSetFromOptions(adaptor);
4588:         DMAdaptorSetUp(adaptor);
4589:         DMAdaptorAdapt(adaptor, x, DM_ADAPTATION_INITIAL, &dm, &x);
4590:         DMAdaptorDestroy(&adaptor);
4591:         incall = PETSC_FALSE;
4592:       }
4593:       /* Use grid sequencing to adapt */
4594:       num  = 0;
4595:       PetscOptionsGetInt(NULL, ((PetscObject) snes)->prefix, "-snes_adapt_sequence", &num, NULL);
4596:       if (num) {
4597:         DMAdaptor adaptor;

4599:         incall = PETSC_TRUE;
4600:         DMAdaptorCreate(PetscObjectComm((PetscObject)snes), &adaptor);
4601:         DMAdaptorSetSolver(adaptor, snes);
4602:         DMAdaptorSetSequenceLength(adaptor, num);
4603:         DMAdaptorSetFromOptions(adaptor);
4604:         DMAdaptorSetUp(adaptor);
4605:         DMAdaptorAdapt(adaptor, x, DM_ADAPTATION_SEQUENTIAL, &dm, &x);
4606:         DMAdaptorDestroy(&adaptor);
4607:         incall = PETSC_FALSE;
4608:       }
4609:     }
4610:   }
4611:   if (!x) { x = snes->vec_sol; }
4612:   if (!x) {
4613:     SNESGetDM(snes,&dm);
4614:     DMCreateGlobalVector(dm,&xcreated);
4615:     x    = xcreated;
4616:   }
4617:   SNESViewFromOptions(snes,NULL,"-snes_view_pre");

4619:   for (grid=0; grid<snes->gridsequence; grid++) PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));
4620:   for (grid=0; grid<snes->gridsequence+1; grid++) {

4622:     /* set solution vector */
4623:     if (!grid) PetscObjectReference((PetscObject)x);
4624:     VecDestroy(&snes->vec_sol);
4625:     snes->vec_sol = x;
4626:     SNESGetDM(snes,&dm);

4628:     /* set affine vector if provided */
4629:     if (b) PetscObjectReference((PetscObject)b);
4630:     VecDestroy(&snes->vec_rhs);
4631:     snes->vec_rhs = b;

4636:     if (!snes->vec_sol_update /* && snes->vec_sol */) {
4637:       VecDuplicate(snes->vec_sol,&snes->vec_sol_update);
4638:       PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);
4639:     }
4640:     DMShellSetGlobalVector(dm,snes->vec_sol);
4641:     SNESSetUp(snes);

4643:     if (!grid) {
4644:       if (snes->ops->computeinitialguess) {
4645:         (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);
4646:       }
4647:     }

4649:     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
4650:     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}

4652:     PetscLogEventBegin(SNES_Solve,snes,0,0,0);
4653:     (*snes->ops->solve)(snes);
4654:     PetscLogEventEnd(SNES_Solve,snes,0,0,0);
4656:     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */

4658:     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
4659:     if (snes->lagpre_persist) snes->pre_iter += snes->iter;

4661:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_test_local_min",NULL,NULL,&flg);
4662:     if (flg && !PetscPreLoadingOn) SNESTestLocalMin(snes);
4663:     /* Call converged reason views. This may involve user-provided viewers as well */
4664:     SNESConvergedReasonViewFromOptions(snes);

4667:     if (snes->reason < 0) break;
4668:     if (grid <  snes->gridsequence) {
4669:       DM  fine;
4670:       Vec xnew;
4671:       Mat interp;

4673:       DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);
4675:       DMCreateInterpolation(snes->dm,fine,&interp,NULL);
4676:       DMCreateGlobalVector(fine,&xnew);
4677:       MatInterpolate(interp,x,xnew);
4678:       DMInterpolate(snes->dm,interp,fine);
4679:       MatDestroy(&interp);
4680:       x    = xnew;

4682:       SNESReset(snes);
4683:       SNESSetDM(snes,fine);
4684:       SNESResetFromOptions(snes);
4685:       DMDestroy(&fine);
4686:       PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));
4687:     }
4688:   }
4689:   SNESViewFromOptions(snes,NULL,"-snes_view");
4690:   VecViewFromOptions(snes->vec_sol,(PetscObject)snes,"-snes_view_solution");
4691:   DMMonitor(snes->dm);
4692:   SNESMonitorPauseFinal_Internal(snes);

4694:   VecDestroy(&xcreated);
4695:   PetscObjectSAWsBlock((PetscObject)snes);
4696:   return 0;
4697: }

4699: /* --------- Internal routines for SNES Package --------- */

4701: /*@C
4702:    SNESSetType - Sets the method for the nonlinear solver.

4704:    Collective on SNES

4706:    Input Parameters:
4707: +  snes - the SNES context
4708: -  type - a known method

4710:    Options Database Key:
4711: .  -snes_type <type> - Sets the method; use -help for a list
4712:    of available methods (for instance, newtonls or newtontr)

4714:    Notes:
4715:    See "petsc/include/petscsnes.h" for available methods (for instance)
4716: +    SNESNEWTONLS - Newton's method with line search
4717:      (systems of nonlinear equations)
4718: -    SNESNEWTONTR - Newton's method with trust region
4719:      (systems of nonlinear equations)

4721:   Normally, it is best to use the SNESSetFromOptions() command and then
4722:   set the SNES solver type from the options database rather than by using
4723:   this routine.  Using the options database provides the user with
4724:   maximum flexibility in evaluating the many nonlinear solvers.
4725:   The SNESSetType() routine is provided for those situations where it
4726:   is necessary to set the nonlinear solver independently of the command
4727:   line or options database.  This might be the case, for example, when
4728:   the choice of solver changes during the execution of the program,
4729:   and the user's application is taking responsibility for choosing the
4730:   appropriate method.

4732:     Developer Notes:
4733:     SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
4734:     the constructor in that list and calls it to create the spexific object.

4736:   Level: intermediate

4738: .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()

4740: @*/
4741: PetscErrorCode  SNESSetType(SNES snes,SNESType type)
4742: {
4743:   PetscBool      match;
4744:   PetscErrorCode (*r)(SNES);


4749:   PetscObjectTypeCompare((PetscObject)snes,type,&match);
4750:   if (match) return 0;

4752:   PetscFunctionListFind(SNESList,type,&r);
4754:   /* Destroy the previous private SNES context */
4755:   if (snes->ops->destroy) {
4756:     (*(snes)->ops->destroy)(snes);
4757:     snes->ops->destroy = NULL;
4758:   }
4759:   /* Reinitialize function pointers in SNESOps structure */
4760:   snes->ops->setup          = NULL;
4761:   snes->ops->solve          = NULL;
4762:   snes->ops->view           = NULL;
4763:   snes->ops->setfromoptions = NULL;
4764:   snes->ops->destroy        = NULL;

4766:   /* It may happen the user has customized the line search before calling SNESSetType */
4767:   if (((PetscObject)snes)->type_name) SNESLineSearchDestroy(&snes->linesearch);

4769:   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
4770:   snes->setupcalled = PETSC_FALSE;

4772:   PetscObjectChangeTypeName((PetscObject)snes,type);
4773:   (*r)(snes);
4774:   return 0;
4775: }

4777: /*@C
4778:    SNESGetType - Gets the SNES method type and name (as a string).

4780:    Not Collective

4782:    Input Parameter:
4783: .  snes - nonlinear solver context

4785:    Output Parameter:
4786: .  type - SNES method (a character string)

4788:    Level: intermediate

4790: @*/
4791: PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
4792: {
4795:   *type = ((PetscObject)snes)->type_name;
4796:   return 0;
4797: }

4799: /*@
4800:   SNESSetSolution - Sets the solution vector for use by the SNES routines.

4802:   Logically Collective on SNES

4804:   Input Parameters:
4805: + snes - the SNES context obtained from SNESCreate()
4806: - u    - the solution vector

4808:   Level: beginner

4810: @*/
4811: PetscErrorCode SNESSetSolution(SNES snes, Vec u)
4812: {
4813:   DM             dm;

4817:   PetscObjectReference((PetscObject) u);
4818:   VecDestroy(&snes->vec_sol);

4820:   snes->vec_sol = u;

4822:   SNESGetDM(snes, &dm);
4823:   DMShellSetGlobalVector(dm, u);
4824:   return 0;
4825: }

4827: /*@
4828:    SNESGetSolution - Returns the vector where the approximate solution is
4829:    stored. This is the fine grid solution when using SNESSetGridSequence().

4831:    Not Collective, but Vec is parallel if SNES is parallel

4833:    Input Parameter:
4834: .  snes - the SNES context

4836:    Output Parameter:
4837: .  x - the solution

4839:    Level: intermediate

4841: .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
4842: @*/
4843: PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
4844: {
4847:   *x = snes->vec_sol;
4848:   return 0;
4849: }

4851: /*@
4852:    SNESGetSolutionUpdate - Returns the vector where the solution update is
4853:    stored.

4855:    Not Collective, but Vec is parallel if SNES is parallel

4857:    Input Parameter:
4858: .  snes - the SNES context

4860:    Output Parameter:
4861: .  x - the solution update

4863:    Level: advanced

4865: .seealso: SNESGetSolution(), SNESGetFunction()
4866: @*/
4867: PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
4868: {
4871:   *x = snes->vec_sol_update;
4872:   return 0;
4873: }

4875: /*@C
4876:    SNESGetFunction - Returns the vector where the function is stored.

4878:    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.

4880:    Input Parameter:
4881: .  snes - the SNES context

4883:    Output Parameters:
4884: +  r - the vector that is used to store residuals (or NULL if you don't want it)
4885: .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
4886: -  ctx - the function context (or NULL if you don't want it)

4888:    Level: advanced

4890:     Notes: The vector r DOES NOT, in general contain the current value of the SNES nonlinear function

4892: .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
4893: @*/
4894: PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
4895: {
4896:   DM             dm;

4899:   if (r) {
4900:     if (!snes->vec_func) {
4901:       if (snes->vec_rhs) {
4902:         VecDuplicate(snes->vec_rhs,&snes->vec_func);
4903:       } else if (snes->vec_sol) {
4904:         VecDuplicate(snes->vec_sol,&snes->vec_func);
4905:       } else if (snes->dm) {
4906:         DMCreateGlobalVector(snes->dm,&snes->vec_func);
4907:       }
4908:     }
4909:     *r = snes->vec_func;
4910:   }
4911:   SNESGetDM(snes,&dm);
4912:   DMSNESGetFunction(dm,f,ctx);
4913:   return 0;
4914: }

4916: /*@C
4917:    SNESGetNGS - Returns the NGS function and context.

4919:    Input Parameter:
4920: .  snes - the SNES context

4922:    Output Parameters:
4923: +  f - the function (or NULL) see SNESNGSFunction for details
4924: -  ctx    - the function context (or NULL)

4926:    Level: advanced

4928: .seealso: SNESSetNGS(), SNESGetFunction()
4929: @*/

4931: PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
4932: {
4933:   DM             dm;

4936:   SNESGetDM(snes,&dm);
4937:   DMSNESGetNGS(dm,f,ctx);
4938:   return 0;
4939: }

4941: /*@C
4942:    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4943:    SNES options in the database.

4945:    Logically Collective on SNES

4947:    Input Parameters:
4948: +  snes - the SNES context
4949: -  prefix - the prefix to prepend to all option names

4951:    Notes:
4952:    A hyphen (-) must NOT be given at the beginning of the prefix name.
4953:    The first character of all runtime options is AUTOMATICALLY the hyphen.

4955:    Level: advanced

4957: .seealso: SNESSetFromOptions()
4958: @*/
4959: PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4960: {
4962:   PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);
4963:   if (!snes->ksp) SNESGetKSP(snes,&snes->ksp);
4964:   if (snes->linesearch) {
4965:     SNESGetLineSearch(snes,&snes->linesearch);
4966:     PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);
4967:   }
4968:   KSPSetOptionsPrefix(snes->ksp,prefix);
4969:   return 0;
4970: }

4972: /*@C
4973:    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4974:    SNES options in the database.

4976:    Logically Collective on SNES

4978:    Input Parameters:
4979: +  snes - the SNES context
4980: -  prefix - the prefix to prepend to all option names

4982:    Notes:
4983:    A hyphen (-) must NOT be given at the beginning of the prefix name.
4984:    The first character of all runtime options is AUTOMATICALLY the hyphen.

4986:    Level: advanced

4988: .seealso: SNESGetOptionsPrefix()
4989: @*/
4990: PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4991: {
4993:   PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);
4994:   if (!snes->ksp) SNESGetKSP(snes,&snes->ksp);
4995:   if (snes->linesearch) {
4996:     SNESGetLineSearch(snes,&snes->linesearch);
4997:     PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);
4998:   }
4999:   KSPAppendOptionsPrefix(snes->ksp,prefix);
5000:   return 0;
5001: }

5003: /*@C
5004:    SNESGetOptionsPrefix - Sets the prefix used for searching for all
5005:    SNES options in the database.

5007:    Not Collective

5009:    Input Parameter:
5010: .  snes - the SNES context

5012:    Output Parameter:
5013: .  prefix - pointer to the prefix string used

5015:    Notes:
5016:     On the fortran side, the user should pass in a string 'prefix' of
5017:    sufficient length to hold the prefix.

5019:    Level: advanced

5021: .seealso: SNESAppendOptionsPrefix()
5022: @*/
5023: PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
5024: {
5026:   PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);
5027:   return 0;
5028: }

5030: /*@C
5031:   SNESRegister - Adds a method to the nonlinear solver package.

5033:    Not collective

5035:    Input Parameters:
5036: +  name_solver - name of a new user-defined solver
5037: -  routine_create - routine to create method context

5039:    Notes:
5040:    SNESRegister() may be called multiple times to add several user-defined solvers.

5042:    Sample usage:
5043: .vb
5044:    SNESRegister("my_solver",MySolverCreate);
5045: .ve

5047:    Then, your solver can be chosen with the procedural interface via
5048: $     SNESSetType(snes,"my_solver")
5049:    or at runtime via the option
5050: $     -snes_type my_solver

5052:    Level: advanced

5054:     Note: If your function is not being put into a shared library then use SNESRegister() instead

5056: .seealso: SNESRegisterAll(), SNESRegisterDestroy()

5058:   Level: advanced
5059: @*/
5060: PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
5061: {
5062:   SNESInitializePackage();
5063:   PetscFunctionListAdd(&SNESList,sname,function);
5064:   return 0;
5065: }

5067: PetscErrorCode  SNESTestLocalMin(SNES snes)
5068: {
5069:   PetscInt       N,i,j;
5070:   Vec            u,uh,fh;
5071:   PetscScalar    value;
5072:   PetscReal      norm;

5074:   SNESGetSolution(snes,&u);
5075:   VecDuplicate(u,&uh);
5076:   VecDuplicate(u,&fh);

5078:   /* currently only works for sequential */
5079:   PetscPrintf(PetscObjectComm((PetscObject)snes),"Testing FormFunction() for local min\n");
5080:   VecGetSize(u,&N);
5081:   for (i=0; i<N; i++) {
5082:     VecCopy(u,uh);
5083:     PetscPrintf(PetscObjectComm((PetscObject)snes),"i = %D\n",i);
5084:     for (j=-10; j<11; j++) {
5085:       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
5086:       VecSetValue(uh,i,value,ADD_VALUES);
5087:       SNESComputeFunction(snes,uh,fh);
5088:       VecNorm(fh,NORM_2,&norm);
5089:       PetscPrintf(PetscObjectComm((PetscObject)snes),"       j norm %D %18.16e\n",j,norm);
5090:       value = -value;
5091:       VecSetValue(uh,i,value,ADD_VALUES);
5092:     }
5093:   }
5094:   VecDestroy(&uh);
5095:   VecDestroy(&fh);
5096:   return 0;
5097: }

5099: /*@
5100:    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
5101:    computing relative tolerance for linear solvers within an inexact
5102:    Newton method.

5104:    Logically Collective on SNES

5106:    Input Parameters:
5107: +  snes - SNES context
5108: -  flag - PETSC_TRUE or PETSC_FALSE

5110:     Options Database:
5111: +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
5112: .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
5113: .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
5114: .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
5115: .  -snes_ksp_ew_gamma <gamma> - Sets gamma
5116: .  -snes_ksp_ew_alpha <alpha> - Sets alpha
5117: .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
5118: -  -snes_ksp_ew_threshold <threshold> - Sets threshold

5120:    Notes:
5121:    Currently, the default is to use a constant relative tolerance for
5122:    the inner linear solvers.  Alternatively, one can use the
5123:    Eisenstat-Walker method, where the relative convergence tolerance
5124:    is reset at each Newton iteration according progress of the nonlinear
5125:    solver.

5127:    Level: advanced

5129:    Reference:
5130:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
5131:    inexact Newton method", SISC 17 (1), pp.16-32, 1996.

5133: .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
5134: @*/
5135: PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
5136: {
5139:   snes->ksp_ewconv = flag;
5140:   return 0;
5141: }

5143: /*@
5144:    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
5145:    for computing relative tolerance for linear solvers within an
5146:    inexact Newton method.

5148:    Not Collective

5150:    Input Parameter:
5151: .  snes - SNES context

5153:    Output Parameter:
5154: .  flag - PETSC_TRUE or PETSC_FALSE

5156:    Notes:
5157:    Currently, the default is to use a constant relative tolerance for
5158:    the inner linear solvers.  Alternatively, one can use the
5159:    Eisenstat-Walker method, where the relative convergence tolerance
5160:    is reset at each Newton iteration according progress of the nonlinear
5161:    solver.

5163:    Level: advanced

5165:    Reference:
5166:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
5167:    inexact Newton method", SISC 17 (1), pp.16-32, 1996.

5169: .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
5170: @*/
5171: PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
5172: {
5175:   *flag = snes->ksp_ewconv;
5176:   return 0;
5177: }

5179: /*@
5180:    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
5181:    convergence criteria for the linear solvers within an inexact
5182:    Newton method.

5184:    Logically Collective on SNES

5186:    Input Parameters:
5187: +    snes - SNES context
5188: .    version - version 1, 2 (default is 2) or 3
5189: .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
5190: .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
5191: .    gamma - multiplicative factor for version 2 rtol computation
5192:              (0 <= gamma2 <= 1)
5193: .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
5194: .    alpha2 - power for safeguard
5195: -    threshold - threshold for imposing safeguard (0 < threshold < 1)

5197:    Note:
5198:    Version 3 was contributed by Luis Chacon, June 2006.

5200:    Use PETSC_DEFAULT to retain the default for any of the parameters.

5202:    Level: advanced

5204:    Reference:
5205:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
5206:    inexact Newton method", Utah State University Math. Stat. Dept. Res.
5207:    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.

5209: .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
5210: @*/
5211: PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
5212: {
5213:   SNESKSPEW *kctx;

5216:   kctx = (SNESKSPEW*)snes->kspconvctx;

5226:   if (version != PETSC_DEFAULT)   kctx->version   = version;
5227:   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
5228:   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
5229:   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
5230:   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
5231:   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
5232:   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;

5240:   return 0;
5241: }

5243: /*@
5244:    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
5245:    convergence criteria for the linear solvers within an inexact
5246:    Newton method.

5248:    Not Collective

5250:    Input Parameter:
5251: .    snes - SNES context

5253:    Output Parameters:
5254: +    version - version 1, 2 (default is 2) or 3
5255: .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
5256: .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
5257: .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
5258: .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
5259: .    alpha2 - power for safeguard
5260: -    threshold - threshold for imposing safeguard (0 < threshold < 1)

5262:    Level: advanced

5264: .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
5265: @*/
5266: PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
5267: {
5268:   SNESKSPEW *kctx;

5271:   kctx = (SNESKSPEW*)snes->kspconvctx;
5273:   if (version)   *version   = kctx->version;
5274:   if (rtol_0)    *rtol_0    = kctx->rtol_0;
5275:   if (rtol_max)  *rtol_max  = kctx->rtol_max;
5276:   if (gamma)     *gamma     = kctx->gamma;
5277:   if (alpha)     *alpha     = kctx->alpha;
5278:   if (alpha2)    *alpha2    = kctx->alpha2;
5279:   if (threshold) *threshold = kctx->threshold;
5280:   return 0;
5281: }

5283:  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
5284: {
5285:   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
5286:   PetscReal      rtol  = PETSC_DEFAULT,stol;

5288:   if (!snes->ksp_ewconv) return 0;
5289:   if (!snes->iter) {
5290:     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
5291:     VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);
5292:   }
5293:   else {
5294:     if (kctx->version == 1) {
5295:       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
5296:       if (rtol < 0.0) rtol = -rtol;
5297:       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
5298:       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
5299:     } else if (kctx->version == 2) {
5300:       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
5301:       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
5302:       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
5303:     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
5304:       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
5305:       /* safeguard: avoid sharp decrease of rtol */
5306:       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
5307:       stol = PetscMax(rtol,stol);
5308:       rtol = PetscMin(kctx->rtol_0,stol);
5309:       /* safeguard: avoid oversolving */
5310:       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
5311:       stol = PetscMax(rtol,stol);
5312:       rtol = PetscMin(kctx->rtol_0,stol);
5313:     } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
5314:   }
5315:   /* safeguard: avoid rtol greater than one */
5316:   rtol = PetscMin(rtol,kctx->rtol_max);
5317:   KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);
5318:   PetscInfo(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);
5319:   return 0;
5320: }

5322: PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
5323: {
5324:   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
5325:   PCSide         pcside;
5326:   Vec            lres;

5328:   if (!snes->ksp_ewconv) return 0;
5329:   KSPGetTolerances(ksp,&kctx->rtol_last,NULL,NULL,NULL);
5330:   kctx->norm_last = snes->norm;
5331:   if (kctx->version == 1) {
5332:     PC        pc;
5333:     PetscBool isNone;

5335:     KSPGetPC(ksp, &pc);
5336:     PetscObjectTypeCompare((PetscObject) pc, PCNONE, &isNone);
5337:     KSPGetPCSide(ksp,&pcside);
5338:      if (pcside == PC_RIGHT || isNone) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
5339:       /* KSP residual is true linear residual */
5340:       KSPGetResidualNorm(ksp,&kctx->lresid_last);
5341:     } else {
5342:       /* KSP residual is preconditioned residual */
5343:       /* compute true linear residual norm */
5344:       VecDuplicate(b,&lres);
5345:       MatMult(snes->jacobian,x,lres);
5346:       VecAYPX(lres,-1.0,b);
5347:       VecNorm(lres,NORM_2,&kctx->lresid_last);
5348:       VecDestroy(&lres);
5349:     }
5350:   }
5351:   return 0;
5352: }

5354: /*@
5355:    SNESGetKSP - Returns the KSP context for a SNES solver.

5357:    Not Collective, but if SNES object is parallel, then KSP object is parallel

5359:    Input Parameter:
5360: .  snes - the SNES context

5362:    Output Parameter:
5363: .  ksp - the KSP context

5365:    Notes:
5366:    The user can then directly manipulate the KSP context to set various
5367:    options, etc.  Likewise, the user can then extract and manipulate the
5368:    PC contexts as well.

5370:    Level: beginner

5372: .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
5373: @*/
5374: PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
5375: {

5379:   if (!snes->ksp) {
5380:     KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);
5381:     PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);
5382:     PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);

5384:     KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);
5385:     KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);

5387:     KSPMonitorSetFromOptions(snes->ksp, "-snes_monitor_ksp", "snes_preconditioned_residual", snes);
5388:     PetscObjectSetOptions((PetscObject)snes->ksp,((PetscObject)snes)->options);
5389:   }
5390:   *ksp = snes->ksp;
5391:   return 0;
5392: }

5394: #include <petsc/private/dmimpl.h>
5395: /*@
5396:    SNESSetDM - Sets the DM that may be used by some nonlinear solvers or their underlying preconditioners

5398:    Logically Collective on SNES

5400:    Input Parameters:
5401: +  snes - the nonlinear solver context
5402: -  dm - the dm, cannot be NULL

5404:    Notes:
5405:    A DM can only be used for solving one problem at a time because information about the problem is stored on the DM,
5406:    even when not using interfaces like DMSNESSetFunction().  Use DMClone() to get a distinct DM when solving different
5407:    problems using the same function space.

5409:    Level: intermediate

5411: .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
5412: @*/
5413: PetscErrorCode  SNESSetDM(SNES snes,DM dm)
5414: {
5415:   KSP            ksp;
5416:   DMSNES         sdm;

5420:   PetscObjectReference((PetscObject)dm);
5421:   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
5422:     if (snes->dm->dmsnes && !dm->dmsnes) {
5423:       DMCopyDMSNES(snes->dm,dm);
5424:       DMGetDMSNES(snes->dm,&sdm);
5425:       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
5426:     }
5427:     DMCoarsenHookRemove(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);
5428:     DMDestroy(&snes->dm);
5429:   }
5430:   snes->dm     = dm;
5431:   snes->dmAuto = PETSC_FALSE;

5433:   SNESGetKSP(snes,&ksp);
5434:   KSPSetDM(ksp,dm);
5435:   KSPSetDMActive(ksp,PETSC_FALSE);
5436:   if (snes->npc) {
5437:     SNESSetDM(snes->npc,snes->dm);
5438:     SNESSetNPCSide(snes,snes->npcside);
5439:   }
5440:   return 0;
5441: }

5443: /*@
5444:    SNESGetDM - Gets the DM that may be used by some preconditioners

5446:    Not Collective but DM obtained is parallel on SNES

5448:    Input Parameter:
5449: . snes - the preconditioner context

5451:    Output Parameter:
5452: .  dm - the dm

5454:    Level: intermediate

5456: .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
5457: @*/
5458: PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
5459: {
5461:   if (!snes->dm) {
5462:     DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);
5463:     snes->dmAuto = PETSC_TRUE;
5464:   }
5465:   *dm = snes->dm;
5466:   return 0;
5467: }

5469: /*@
5470:   SNESSetNPC - Sets the nonlinear preconditioner to be used.

5472:   Collective on SNES

5474:   Input Parameters:
5475: + snes - iterative context obtained from SNESCreate()
5476: - pc   - the preconditioner object

5478:   Notes:
5479:   Use SNESGetNPC() to retrieve the preconditioner context (for example,
5480:   to configure it using the API).

5482:   Level: developer

5484: .seealso: SNESGetNPC(), SNESHasNPC()
5485: @*/
5486: PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
5487: {
5491:   PetscObjectReference((PetscObject) pc);
5492:   SNESDestroy(&snes->npc);
5493:   snes->npc = pc;
5494:   PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->npc);
5495:   return 0;
5496: }

5498: /*@
5499:   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.

5501:   Not Collective; but any changes to the obtained SNES object must be applied collectively

5503:   Input Parameter:
5504: . snes - iterative context obtained from SNESCreate()

5506:   Output Parameter:
5507: . pc - preconditioner context

5509:   Options Database:
5510: . -npc_snes_type <type> - set the type of the SNES to use as the nonlinear preconditioner

5512:   Notes:
5513:     If a SNES was previously set with SNESSetNPC() then that SNES is returned, otherwise a new SNES object is created.

5515:     The (preconditioner) SNES returned automatically inherits the same nonlinear function and Jacobian supplied to the original
5516:     SNES during SNESSetUp()

5518:   Level: developer

5520: .seealso: SNESSetNPC(), SNESHasNPC(), SNES, SNESCreate()
5521: @*/
5522: PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
5523: {
5524:   const char     *optionsprefix;

5528:   if (!snes->npc) {
5529:     SNESCreate(PetscObjectComm((PetscObject)snes),&snes->npc);
5530:     PetscObjectIncrementTabLevel((PetscObject)snes->npc,(PetscObject)snes,1);
5531:     PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->npc);
5532:     SNESGetOptionsPrefix(snes,&optionsprefix);
5533:     SNESSetOptionsPrefix(snes->npc,optionsprefix);
5534:     SNESAppendOptionsPrefix(snes->npc,"npc_");
5535:     SNESSetCountersReset(snes->npc,PETSC_FALSE);
5536:   }
5537:   *pc = snes->npc;
5538:   return 0;
5539: }

5541: /*@
5542:   SNESHasNPC - Returns whether a nonlinear preconditioner exists

5544:   Not Collective

5546:   Input Parameter:
5547: . snes - iterative context obtained from SNESCreate()

5549:   Output Parameter:
5550: . has_npc - whether the SNES has an NPC or not

5552:   Level: developer

5554: .seealso: SNESSetNPC(), SNESGetNPC()
5555: @*/
5556: PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
5557: {
5559:   *has_npc = (PetscBool) (snes->npc ? PETSC_TRUE : PETSC_FALSE);
5560:   return 0;
5561: }

5563: /*@
5564:     SNESSetNPCSide - Sets the preconditioning side.

5566:     Logically Collective on SNES

5568:     Input Parameter:
5569: .   snes - iterative context obtained from SNESCreate()

5571:     Output Parameter:
5572: .   side - the preconditioning side, where side is one of
5573: .vb
5574:       PC_LEFT - left preconditioning
5575:       PC_RIGHT - right preconditioning (default for most nonlinear solvers)
5576: .ve

5578:     Options Database Keys:
5579: .   -snes_npc_side <right,left> - nonlinear preconditioner side

5581:     Notes:
5582:     SNESNRICHARDSON and SNESNCG only support left preconditioning.

5584:     Level: intermediate

5586: .seealso: SNESGetNPCSide(), KSPSetPCSide()
5587: @*/
5588: PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
5589: {
5592:   if (side == PC_SIDE_DEFAULT) side = PC_RIGHT;
5594:   snes->npcside = side;
5595:   return 0;
5596: }

5598: /*@
5599:     SNESGetNPCSide - Gets the preconditioning side.

5601:     Not Collective

5603:     Input Parameter:
5604: .   snes - iterative context obtained from SNESCreate()

5606:     Output Parameter:
5607: .   side - the preconditioning side, where side is one of
5608: .vb
5609:       PC_LEFT - left preconditioning
5610:       PC_RIGHT - right preconditioning (default for most nonlinear solvers)
5611: .ve

5613:     Level: intermediate

5615: .seealso: SNESSetNPCSide(), KSPGetPCSide()
5616: @*/
5617: PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
5618: {
5621:   *side = snes->npcside;
5622:   return 0;
5623: }

5625: /*@
5626:   SNESSetLineSearch - Sets the linesearch on the SNES instance.

5628:   Collective on SNES

5630:   Input Parameters:
5631: + snes - iterative context obtained from SNESCreate()
5632: - linesearch   - the linesearch object

5634:   Notes:
5635:   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
5636:   to configure it using the API).

5638:   Level: developer

5640: .seealso: SNESGetLineSearch()
5641: @*/
5642: PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
5643: {
5647:   PetscObjectReference((PetscObject) linesearch);
5648:   SNESLineSearchDestroy(&snes->linesearch);

5650:   snes->linesearch = linesearch;

5652:   PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);
5653:   return 0;
5654: }

5656: /*@
5657:   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
5658:   or creates a default line search instance associated with the SNES and returns it.

5660:   Not Collective

5662:   Input Parameter:
5663: . snes - iterative context obtained from SNESCreate()

5665:   Output Parameter:
5666: . linesearch - linesearch context

5668:   Level: beginner

5670: .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
5671: @*/
5672: PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
5673: {
5674:   const char     *optionsprefix;

5678:   if (!snes->linesearch) {
5679:     SNESGetOptionsPrefix(snes, &optionsprefix);
5680:     SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);
5681:     SNESLineSearchSetSNES(snes->linesearch, snes);
5682:     SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);
5683:     PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);
5684:     PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);
5685:   }
5686:   *linesearch = snes->linesearch;
5687:   return 0;
5688: }