Actual source code: composite.c

  1: /*
  2:       Defines a preconditioner that can consist of a collection of PCs
  3: */
 4:  #include src/ksp/pc/pcimpl.h
 5:  #include petscksp.h

  7: typedef struct _PC_CompositeLink *PC_CompositeLink;
  8: struct _PC_CompositeLink {
  9:   PC               pc;
 10:   PC_CompositeLink next;
 11: };
 12: 
 13: typedef struct {
 14:   PC_CompositeLink head;
 15:   PCCompositeType  type;
 16:   Vec              work1;
 17:   Vec              work2;
 18:   PetscScalar      alpha;
 19:   PetscTruth       use_true_matrix;
 20: } PC_Composite;

 24: static PetscErrorCode PCApply_Composite_Multiplicative(PC pc,Vec x,Vec y)
 25: {
 26:   PetscErrorCode   ierr;
 27:   PC_Composite     *jac = (PC_Composite*)pc->data;
 28:   PC_CompositeLink next = jac->head;
 29:   PetscScalar      one = 1.0,mone = -1.0;
 30:   Mat              mat = pc->pmat;

 33:   if (!next) {
 34:     SETERRQ(PETSC_ERR_ARG_WRONGSTATE,"No composite preconditioners supplied via PCCompositeAddPC()");
 35:   }
 36:   if (next->next && !jac->work2) { /* allocate second work vector */
 37:     VecDuplicate(jac->work1,&jac->work2);
 38:   }
 39:   PCApply(next->pc,x,y);
 40:   if (jac->use_true_matrix) mat = pc->mat;
 41:   while (next->next) {
 42:     next = next->next;
 43:     MatMult(mat,y,jac->work1);
 44:     VecWAXPY(&mone,jac->work1,x,jac->work2);
 45:     PCApply(next->pc,jac->work2,jac->work1);
 46:     VecAXPY(&one,jac->work1,y);
 47:   }

 49:   return(0);
 50: }

 52: /*
 53:     This is very special for a matrix of the form alpha I + R + S
 54: where first preconditioner is built from alpha I + S and second from
 55: alpha I + R
 56: */
 59: static PetscErrorCode PCApply_Composite_Special(PC pc,Vec x,Vec y)
 60: {
 61:   PetscErrorCode   ierr;
 62:   PC_Composite     *jac = (PC_Composite*)pc->data;
 63:   PC_CompositeLink next = jac->head;

 66:   if (!next) {
 67:     SETERRQ(PETSC_ERR_ARG_WRONGSTATE,"No composite preconditioners supplied via PCCompositeAddPC()");
 68:   }
 69:   if (!next->next || next->next->next) {
 70:     SETERRQ(PETSC_ERR_ARG_WRONGSTATE,"Special composite preconditioners requires exactly two PCs");
 71:   }

 73:   PCApply(next->pc,x,jac->work1);
 74:   PCApply(next->next->pc,jac->work1,y);
 75:   return(0);
 76: }

 80: static PetscErrorCode PCApply_Composite_Additive(PC pc,Vec x,Vec y)
 81: {
 82:   PetscErrorCode   ierr;
 83:   PC_Composite     *jac = (PC_Composite*)pc->data;
 84:   PC_CompositeLink next = jac->head;
 85:   PetscScalar      one = 1.0;

 88:   if (!next) {
 89:     SETERRQ(PETSC_ERR_ARG_WRONGSTATE,"No composite preconditioners supplied via PCCompositeAddPC()");
 90:   }
 91:   PCApply(next->pc,x,y);
 92:   while (next->next) {
 93:     next = next->next;
 94:     PCApply(next->pc,x,jac->work1);
 95:     VecAXPY(&one,jac->work1,y);
 96:   }
 97:   return(0);
 98: }

102: static PetscErrorCode PCSetUp_Composite(PC pc)
103: {
104:   PetscErrorCode   ierr;
105:   PC_Composite     *jac = (PC_Composite*)pc->data;
106:   PC_CompositeLink next = jac->head;

109:   if (!jac->work1) {
110:      MatGetVecs(pc->pmat,&jac->work1,0);
111:   }
112:   while (next) {
113:     PCSetOperators(next->pc,pc->mat,pc->pmat,pc->flag);
114:     next = next->next;
115:   }

117:   return(0);
118: }

122: static PetscErrorCode PCDestroy_Composite(PC pc)
123: {
124:   PC_Composite     *jac = (PC_Composite*)pc->data;
125:   PetscErrorCode   ierr;
126:   PC_CompositeLink next = jac->head;

129:   while (next) {
130:     PCDestroy(next->pc);
131:     next = next->next;
132:   }

134:   if (jac->work1) {VecDestroy(jac->work1);}
135:   if (jac->work2) {VecDestroy(jac->work2);}
136:   PetscFree(jac);
137:   return(0);
138: }

142: static PetscErrorCode PCSetFromOptions_Composite(PC pc)
143: {
144:   PC_Composite     *jac = (PC_Composite*)pc->data;
145:   PetscErrorCode   ierr;
146:   PetscInt         nmax = 8,i,indx;
147:   PC_CompositeLink next;
148:   char             *pcs[8];
149:   const char       *types[] = {"additive","multiplicative","special"};
150:   PetscTruth       flg;

153:   PetscOptionsHead("Composite preconditioner options");
154:     PetscOptionsEList("-pc_composite_type","Type of composition","PCCompositeSetType",types,3,types[0],&indx,&flg);
155:     if (flg) {
156:       PCCompositeSetType(pc,(PCCompositeType)indx);
157:     }
158:     PetscOptionsName("-pc_composite_true","Use true matrix for inner solves","PCCompositeSetUseTrue",&flg);
159:     if (flg) {
160:       PCCompositeSetUseTrue(pc);
161:     }
162:     PetscOptionsStringArray("-pc_composite_pcs","List of composite solvers","PCCompositeAddPC",pcs,&nmax,&flg);
163:     if (flg) {
164:       for (i=0; i<nmax; i++) {
165:         PCCompositeAddPC(pc,pcs[i]);
166:       }
167:     }
168:   PetscOptionsTail();

170:   next = jac->head;
171:   while (next) {
172:     PCSetFromOptions(next->pc);
173:     next = next->next;
174:   }
175:   return(0);
176: }

180: static PetscErrorCode PCView_Composite(PC pc,PetscViewer viewer)
181: {
182:   PC_Composite     *jac = (PC_Composite*)pc->data;
183:   PetscErrorCode   ierr;
184:   PC_CompositeLink next = jac->head;
185:   PetscTruth       iascii;

188:   PetscTypeCompare((PetscObject)viewer,PETSC_VIEWER_ASCII,&iascii);
189:   if (iascii) {
190:     PetscViewerASCIIPrintf(viewer,"PCs on composite preconditioner follow\n");
191:     PetscViewerASCIIPrintf(viewer,"---------------------------------\n");
192:   } else {
193:     SETERRQ1(PETSC_ERR_SUP,"Viewer type %s not supported for PCComposite",((PetscObject)viewer)->type_name);
194:   }
195:   if (iascii) {
196:     PetscViewerASCIIPushTab(viewer);
197:   }
198:   while (next) {
199:     PCView(next->pc,viewer);
200:     next = next->next;
201:   }
202:   if (iascii) {
203:     PetscViewerASCIIPopTab(viewer);
204:     PetscViewerASCIIPrintf(viewer,"---------------------------------\n");
205:   }
206:   return(0);
207: }

209: /* ------------------------------------------------------------------------------*/

214: PetscErrorCode PCCompositeSpecialSetAlpha_Composite(PC pc,PetscScalar alpha)
215: {
216:   PC_Composite *jac = (PC_Composite*)pc->data;
218:   jac->alpha = alpha;
219:   return(0);
220: }

226: PetscErrorCode PCCompositeSetType_Composite(PC pc,PCCompositeType type)
227: {
229:   if (type == PC_COMPOSITE_ADDITIVE) {
230:     pc->ops->apply = PCApply_Composite_Additive;
231:   } else if (type ==  PC_COMPOSITE_MULTIPLICATIVE) {
232:     pc->ops->apply = PCApply_Composite_Multiplicative;
233:   } else if (type ==  PC_COMPOSITE_SPECIAL) {
234:     pc->ops->apply = PCApply_Composite_Special;
235:   } else {
236:     SETERRQ(PETSC_ERR_ARG_WRONG,"Unkown composite preconditioner type");
237:   }
238:   return(0);
239: }

245: PetscErrorCode PCCompositeAddPC_Composite(PC pc,PCType type)
246: {
247:   PC_Composite     *jac;
248:   PC_CompositeLink next,link;
249:   PetscErrorCode   ierr;
250:   PetscInt         cnt = 0;
251:   char             *prefix,newprefix[8];

254:   PetscNew(struct _PC_CompositeLink,&link);
255:   link->next = 0;
256:   PCCreate(pc->comm,&link->pc);

258:   jac  = (PC_Composite*)pc->data;
259:   next = jac->head;
260:   if (!next) {
261:     jac->head = link;
262:   } else {
263:     cnt++;
264:     while (next->next) {
265:       next = next->next;
266:       cnt++;
267:     }
268:     next->next = link;
269:   }
270:   PCGetOptionsPrefix(pc,&prefix);
271:   PCSetOptionsPrefix(link->pc,prefix);
272:   sprintf(newprefix,"sub_%d_",(int)cnt);
273:   PCAppendOptionsPrefix(link->pc,newprefix);
274:   /* type is set after prefix, because some methods may modify prefix, e.g. pcksp */
275:   PCSetType(link->pc,type);

277:   return(0);
278: }

284: PetscErrorCode PCCompositeGetPC_Composite(PC pc,PetscInt n,PC *subpc)
285: {
286:   PC_Composite     *jac;
287:   PC_CompositeLink next;
288:   PetscInt         i;

291:   jac  = (PC_Composite*)pc->data;
292:   next = jac->head;
293:   for (i=0; i<n; i++) {
294:     if (!next->next) {
295:       SETERRQ(PETSC_ERR_ARG_INCOMP,"Not enough PCs in composite preconditioner");
296:     }
297:     next = next->next;
298:   }
299:   *subpc = next->pc;
300:   return(0);
301: }

307: PetscErrorCode PCCompositeSetUseTrue_Composite(PC pc)
308: {
309:   PC_Composite   *jac;

312:   jac                  = (PC_Composite*)pc->data;
313:   jac->use_true_matrix = PETSC_TRUE;
314:   return(0);
315: }

318: /* -------------------------------------------------------------------------------- */
321: /*@C
322:    PCCompositeSetType - Sets the type of composite preconditioner.
323:    
324:    Collective on PC

326:    Input Parameter:
327: .  pc - the preconditioner context
328: .  type - PC_COMPOSITE_ADDITIVE (default), PC_COMPOSITE_MULTIPLICATIVE, PC_COMPOSITE_SPECIAL

330:    Options Database Key:
331: .  -pc_composite_type <type: one of multiplicative, additive, special> - Sets composite preconditioner type

333:    Level: Developer

335: .keywords: PC, set, type, composite preconditioner, additive, multiplicative
336: @*/
337: PetscErrorCode PCCompositeSetType(PC pc,PCCompositeType type)
338: {
339:   PetscErrorCode ierr,(*f)(PC,PCCompositeType);

343:   PetscObjectQueryFunction((PetscObject)pc,"PCCompositeSetType_C",(void (**)(void))&f);
344:   if (f) {
345:     (*f)(pc,type);
346:   }
347:   return(0);
348: }

352: /*@C
353:    PCCompositeSpecialSetAlpha - Sets alpha for the special composite preconditioner
354:      for alphaI + R + S
355:    
356:    Collective on PC

358:    Input Parameter:
359: +  pc - the preconditioner context
360: -  alpha - scale on identity

362:    Level: Developer

364: .keywords: PC, set, type, composite preconditioner, additive, multiplicative
365: @*/
366: PetscErrorCode PCCompositeSpecialSetAlpha(PC pc,PetscScalar alpha)
367: {
368:   PetscErrorCode ierr,(*f)(PC,PetscScalar);

372:   PetscObjectQueryFunction((PetscObject)pc,"PCCompositeSpecialSetAlpha_C",(void (**)(void))&f);
373:   if (f) {
374:     (*f)(pc,alpha);
375:   }
376:   return(0);
377: }

381: /*@C
382:    PCCompositeAddPC - Adds another PC to the composite PC.
383:    
384:    Collective on PC

386:    Input Parameters:
387: .  pc - the preconditioner context
388: .  type - the type of the new preconditioner

390:    Level: Developer

392: .keywords: PC, composite preconditioner, add
393: @*/
394: PetscErrorCode PCCompositeAddPC(PC pc,PCType type)
395: {
396:   PetscErrorCode ierr,(*f)(PC,PCType);

400:   PetscObjectQueryFunction((PetscObject)pc,"PCCompositeAddPC_C",(void (**)(void))&f);
401:   if (f) {
402:     (*f)(pc,type);
403:   }
404:   return(0);
405: }

409: /*@C
410:    PCCompositeGetPC - Gets one of the PC objects in the composite PC.
411:    
412:    Not Collective

414:    Input Parameter:
415: .  pc - the preconditioner context
416: .  n - the number of the pc requested

418:    Output Parameters:
419: .  subpc - the PC requested

421:    Level: Developer

423: .keywords: PC, get, composite preconditioner, sub preconditioner

425: .seealso: PCCompositeAddPC()
426: @*/
427: PetscErrorCode PCCompositeGetPC(PC pc,PetscInt n,PC *subpc)
428: {
429:   PetscErrorCode ierr,(*f)(PC,PetscInt,PC *);

434:   PetscObjectQueryFunction((PetscObject)pc,"PCCompositeGetPC_C",(void (**)(void))&f);
435:   if (f) {
436:     (*f)(pc,n,subpc);
437:   } else {
438:     SETERRQ(PETSC_ERR_ARG_WRONG,"Cannot get pc, not composite type");
439:   }
440:   return(0);
441: }

445: /*@
446:    PCCompositeSetUseTrue - Sets a flag to indicate that the true matrix (rather than
447:                       the matrix used to define the preconditioner) is used to compute
448:                       the residual when the multiplicative scheme is used.

450:    Collective on PC

452:    Input Parameters:
453: .  pc - the preconditioner context

455:    Options Database Key:
456: .  -pc_composite_true - Activates PCCompositeSetUseTrue()

458:    Note:
459:    For the common case in which the preconditioning and linear 
460:    system matrices are identical, this routine is unnecessary.

462:    Level: Developer

464: .keywords: PC, composite preconditioner, set, true, flag

466: .seealso: PCSetOperators(), PCBJacobiSetUseTrueLocal(), PCKSPSetUseTrue()
467: @*/
468: PetscErrorCode PCCompositeSetUseTrue(PC pc)
469: {
470:   PetscErrorCode ierr,(*f)(PC);

474:   PetscObjectQueryFunction((PetscObject)pc,"PCCompositeSetUseTrue_C",(void (**)(void))&f);
475:   if (f) {
476:     (*f)(pc);
477:   }
478:   return(0);
479: }

481: /* -------------------------------------------------------------------------------------------*/

483: /*MC
484:      PCCOMPOSITE - Build a preconditioner by composing together several preconditioners 

486:    Options Database Keys:
487: .  -pc_composite_type <type: one of multiplicative, additive, special> - Sets composite preconditioner type
488: .  -pc_composite_true - Activates PCCompositeSetUseTrue()

490:    Level: intermediate

492:    Concepts: composing solvers

494:    Notes: To use a Krylov method inside the composite preconditioner, set the PCType of one or more
495:           inner PCs to be PCKSP. 
496:           Using a Krylov method inside another Krylov method can be dangerous (you get divergence or
497:           the incorrect answer) unless you use KSPFGMRES as the outter Krylov method


500: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC,
501:            PCSHELL, PCKSP, PCCompositeSetType(), PCCompositeSpecialSetAlpha(), PCCompositeAddPC(),
502:            PCCompositeGetPC(), PCCompositeSetUseTrue()

504: M*/

509: PetscErrorCode PCCreate_Composite(PC pc)
510: {
512:   PC_Composite   *jac;

515:   PetscNew(PC_Composite,&jac);
516:   PetscLogObjectMemory(pc,sizeof(PC_Composite));
517:   pc->ops->apply              = PCApply_Composite_Additive;
518:   pc->ops->setup              = PCSetUp_Composite;
519:   pc->ops->destroy            = PCDestroy_Composite;
520:   pc->ops->setfromoptions     = PCSetFromOptions_Composite;
521:   pc->ops->view               = PCView_Composite;
522:   pc->ops->applyrichardson    = 0;

524:   pc->data               = (void*)jac;
525:   jac->type              = PC_COMPOSITE_ADDITIVE;
526:   jac->work1             = 0;
527:   jac->work2             = 0;
528:   jac->head              = 0;

530:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCCompositeSetType_C","PCCompositeSetType_Composite",
531:                     PCCompositeSetType_Composite);
532:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCCompositeAddPC_C","PCCompositeAddPC_Composite",
533:                     PCCompositeAddPC_Composite);
534:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCCompositeGetPC_C","PCCompositeGetPC_Composite",
535:                     PCCompositeGetPC_Composite);
536:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCCompositeSetUseTrue_C","PCCompositeSetUseTrue_Composite",
537:                     PCCompositeSetUseTrue_Composite);
538:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCCompositeSpecialSetAlpha_C","PCCompositeSpecialSetAlpha_Composite",
539:                     PCCompositeSpecialSetAlpha_Composite);

541:   return(0);
542: }