Actual source code: fas.c
petsc-3.10.5 2019-03-28
1: /* Defines the basic SNES object */
2: #include <../src/snes/impls/fas/fasimpls.h>
4: const char *const SNESFASTypes[] = {"MULTIPLICATIVE","ADDITIVE","FULL","KASKADE","SNESFASType","SNES_FAS",0};
6: static PetscErrorCode SNESReset_FAS(SNES snes)
7: {
8: PetscErrorCode 0;
9: SNES_FAS * fas = (SNES_FAS*)snes->data;
12: SNESDestroy(&fas->smoothu);
13: SNESDestroy(&fas->smoothd);
14: MatDestroy(&fas->inject);
15: MatDestroy(&fas->interpolate);
16: MatDestroy(&fas->restrct);
17: VecDestroy(&fas->rscale);
18: if (fas->galerkin) {
19: VecDestroy(&fas->Xg);
20: VecDestroy(&fas->Fg);
21: }
22: if (fas->next) {SNESReset(fas->next);}
23: return(0);
24: }
26: static PetscErrorCode SNESDestroy_FAS(SNES snes)
27: {
28: SNES_FAS * fas = (SNES_FAS*)snes->data;
29: PetscErrorCode 0;
32: /* recursively resets and then destroys */
33: SNESReset(snes);
34: if (fas->next) {
35: SNESDestroy(&fas->next);
36: }
37: PetscFree(fas);
38: return(0);
39: }
41: static PetscErrorCode SNESSetUp_FAS(SNES snes)
42: {
43: SNES_FAS *fas = (SNES_FAS*) snes->data;
45: PetscInt dm_levels;
46: Vec vec_sol, vec_func, vec_sol_update, vec_rhs; /* preserve these if they're set through the reset */
47: SNES next;
48: PetscBool isFine, hasCreateRestriction;
49: SNESLineSearch linesearch;
50: SNESLineSearch slinesearch;
51: void *lsprectx,*lspostctx;
52: PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
53: PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
56: SNESFASCycleIsFine(snes, &isFine);
57: if (fas->usedmfornumberoflevels && isFine) {
58: DMGetRefineLevel(snes->dm,&dm_levels);
59: dm_levels++;
60: if (dm_levels > fas->levels) {
61: /* we don't want the solution and func vectors to be destroyed in the SNESReset when it's called in SNESFASSetLevels_FAS*/
62: vec_sol = snes->vec_sol;
63: vec_func = snes->vec_func;
64: vec_sol_update = snes->vec_sol_update;
65: vec_rhs = snes->vec_rhs;
66: snes->vec_sol = NULL;
67: snes->vec_func = NULL;
68: snes->vec_sol_update = NULL;
69: snes->vec_rhs = NULL;
71: /* reset the number of levels */
72: SNESFASSetLevels(snes,dm_levels,NULL);
73: SNESSetFromOptions(snes);
75: snes->vec_sol = vec_sol;
76: snes->vec_func = vec_func;
77: snes->vec_rhs = vec_rhs;
78: snes->vec_sol_update = vec_sol_update;
79: }
80: }
81: SNESFASCycleGetCorrection(snes, &next);
82: if (!isFine) snes->gridsequence = 0; /* no grid sequencing inside the multigrid hierarchy! */
84: SNESSetWorkVecs(snes, 2); /* work vectors used for intergrid transfers */
86: /* set up the smoothers if they haven't already been set up */
87: if (!fas->smoothd) {
88: SNESFASCycleCreateSmoother_Private(snes, &fas->smoothd);
89: }
91: if (snes->dm) {
92: /* set the smoother DMs properly */
93: if (fas->smoothu) SNESSetDM(fas->smoothu, snes->dm);
94: SNESSetDM(fas->smoothd, snes->dm);
95: /* construct EVERYTHING from the DM -- including the progressive set of smoothers */
96: if (next) {
97: /* for now -- assume the DM and the evaluation functions have been set externally */
98: if (!next->dm) {
99: DMCoarsen(snes->dm, PetscObjectComm((PetscObject)next), &next->dm);
100: SNESSetDM(next, next->dm);
101: }
102: /* set the interpolation and restriction from the DM */
103: if (!fas->interpolate) {
104: DMCreateInterpolation(next->dm, snes->dm, &fas->interpolate, &fas->rscale);
105: if (!fas->restrct) {
106: DMHasCreateRestriction(next->dm, &hasCreateRestriction);
107: /* DM can create restrictions, use that */
108: if (hasCreateRestriction) {
109: DMCreateRestriction(next->dm, snes->dm, &fas->restrct);
110: } else {
111: PetscObjectReference((PetscObject)fas->interpolate);
112: fas->restrct = fas->interpolate;
113: }
114: }
115: }
116: /* set the injection from the DM */
117: if (!fas->inject) {
118: PetscBool flg;
119: DMHasCreateInjection(next->dm, &flg);
120: if (flg) {
121: DMCreateInjection(next->dm, snes->dm, &fas->inject);
122: }
123: }
124: }
125: }
126: /*pass the smoother, function, and jacobian up to the next level if it's not user set already */
127: if (fas->galerkin) {
128: if (next) {
129: SNESSetFunction(next, NULL, SNESFASGalerkinFunctionDefault, next);
130: }
131: if (fas->smoothd && fas->level != fas->levels - 1) {
132: SNESSetFunction(fas->smoothd, NULL, SNESFASGalerkinFunctionDefault, snes);
133: }
134: if (fas->smoothu && fas->level != fas->levels - 1) {
135: SNESSetFunction(fas->smoothu, NULL, SNESFASGalerkinFunctionDefault, snes);
136: }
137: }
139: /* sets the down (pre) smoother's default norm and sets it from options */
140: if (fas->smoothd) {
141: if (fas->level == 0 && fas->levels != 1) {
142: SNESSetNormSchedule(fas->smoothd, SNES_NORM_NONE);
143: } else {
144: SNESSetNormSchedule(fas->smoothd, SNES_NORM_FINAL_ONLY);
145: }
146: PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)fas->smoothd);
147: SNESSetFromOptions(fas->smoothd);
148: SNESGetLineSearch(snes,&linesearch);
149: SNESGetLineSearch(fas->smoothd,&slinesearch);
150: SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
151: SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
152: SNESLineSearchSetPreCheck(slinesearch,precheck,lsprectx);
153: SNESLineSearchSetPostCheck(slinesearch,postcheck,lspostctx);
154: PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)slinesearch);
156: fas->smoothd->vec_sol = snes->vec_sol;
157: PetscObjectReference((PetscObject)snes->vec_sol);
158: fas->smoothd->vec_sol_update = snes->vec_sol_update;
159: PetscObjectReference((PetscObject)snes->vec_sol_update);
160: fas->smoothd->vec_func = snes->vec_func;
161: PetscObjectReference((PetscObject)snes->vec_func);
163: if (fas->eventsmoothsetup) {PetscLogEventBegin(fas->eventsmoothsetup,fas->smoothd,0,0,0);}
164: SNESSetUp(fas->smoothd);
165: if (fas->eventsmoothsetup) {PetscLogEventEnd(fas->eventsmoothsetup,fas->smoothd,0,0,0);}
166: }
168: /* sets the up (post) smoother's default norm and sets it from options */
169: if (fas->smoothu) {
170: if (fas->level != fas->levels - 1) {
171: SNESSetNormSchedule(fas->smoothu, SNES_NORM_NONE);
172: } else {
173: SNESSetNormSchedule(fas->smoothu, SNES_NORM_FINAL_ONLY);
174: }
175: PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)fas->smoothu);
176: SNESSetFromOptions(fas->smoothu);
177: SNESGetLineSearch(snes,&linesearch);
178: SNESGetLineSearch(fas->smoothu,&slinesearch);
179: SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
180: SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
181: SNESLineSearchSetPreCheck(slinesearch,precheck,lsprectx);
182: SNESLineSearchSetPostCheck(slinesearch,postcheck,lspostctx);
183: PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)slinesearch);
185: fas->smoothu->vec_sol = snes->vec_sol;
186: PetscObjectReference((PetscObject)snes->vec_sol);
187: fas->smoothu->vec_sol_update = snes->vec_sol_update;
188: PetscObjectReference((PetscObject)snes->vec_sol_update);
189: fas->smoothu->vec_func = snes->vec_func;
190: PetscObjectReference((PetscObject)snes->vec_func);
192: if (fas->eventsmoothsetup) {PetscLogEventBegin(fas->eventsmoothsetup,fas->smoothu,0,0,0);}
193: SNESSetUp(fas->smoothu);
194: if (fas->eventsmoothsetup) {PetscLogEventEnd(fas->eventsmoothsetup,fas->smoothu,0,0,0);}
196: }
198: if (next) {
199: /* gotta set up the solution vector for this to work */
200: if (!next->vec_sol) {SNESFASCreateCoarseVec(snes,&next->vec_sol);}
201: if (!next->vec_rhs) {SNESFASCreateCoarseVec(snes,&next->vec_rhs);}
202: PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)next);
203: SNESGetLineSearch(snes,&linesearch);
204: SNESGetLineSearch(fas->next,&slinesearch);
205: SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
206: SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
207: SNESLineSearchSetPreCheck(slinesearch,precheck,lsprectx);
208: SNESLineSearchSetPostCheck(slinesearch,postcheck,lspostctx);
209: PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)slinesearch);
210: SNESSetUp(next);
211: }
212: /* setup FAS work vectors */
213: if (fas->galerkin) {
214: VecDuplicate(snes->vec_sol, &fas->Xg);
215: VecDuplicate(snes->vec_sol, &fas->Fg);
216: }
217: return(0);
218: }
220: static PetscErrorCode SNESSetFromOptions_FAS(PetscOptionItems *PetscOptionsObject,SNES snes)
221: {
222: SNES_FAS *fas = (SNES_FAS*) snes->data;
223: PetscInt levels = 1;
224: PetscBool flg = PETSC_FALSE, upflg = PETSC_FALSE, downflg = PETSC_FALSE, monflg = PETSC_FALSE, galerkinflg = PETSC_FALSE,continuationflg = PETSC_FALSE;
226: SNESFASType fastype;
227: const char *optionsprefix;
228: SNESLineSearch linesearch;
229: PetscInt m, n_up, n_down;
230: SNES next;
231: PetscBool isFine;
234: SNESFASCycleIsFine(snes, &isFine);
235: PetscOptionsHead(PetscOptionsObject,"SNESFAS Options-----------------------------------");
237: /* number of levels -- only process most options on the finest level */
238: if (isFine) {
239: PetscOptionsInt("-snes_fas_levels", "Number of Levels", "SNESFASSetLevels", levels, &levels, &flg);
240: if (!flg && snes->dm) {
241: DMGetRefineLevel(snes->dm,&levels);
242: levels++;
243: fas->usedmfornumberoflevels = PETSC_TRUE;
244: }
245: SNESFASSetLevels(snes, levels, NULL);
246: fastype = fas->fastype;
247: PetscOptionsEnum("-snes_fas_type","FAS correction type","SNESFASSetType",SNESFASTypes,(PetscEnum)fastype,(PetscEnum*)&fastype,&flg);
248: if (flg) {
249: SNESFASSetType(snes, fastype);
250: }
252: SNESGetOptionsPrefix(snes, &optionsprefix);
253: PetscOptionsInt("-snes_fas_cycles","Number of cycles","SNESFASSetCycles",fas->n_cycles,&m,&flg);
254: if (flg) {
255: SNESFASSetCycles(snes, m);
256: }
257: PetscOptionsBool("-snes_fas_continuation","Corrected grid-sequence continuation","SNESFASSetContinuation",fas->continuation,&continuationflg,&flg);
258: if (flg) {
259: SNESFASSetContinuation(snes,continuationflg);
260: }
262: PetscOptionsBool("-snes_fas_galerkin", "Form coarse problems with Galerkin","SNESFASSetGalerkin",fas->galerkin,&galerkinflg,&flg);
263: if (flg) {
264: SNESFASSetGalerkin(snes, galerkinflg);
265: }
267: if (fas->fastype == SNES_FAS_FULL) {
268: PetscOptionsBool("-snes_fas_full_downsweep","Smooth on the initial upsweep for full FAS cycles","SNESFASFullSetDownSweep",fas->full_downsweep,&fas->full_downsweep,&flg);
269: if (flg) {SNESFASFullSetDownSweep(snes,fas->full_downsweep);}
270: }
272: PetscOptionsInt("-snes_fas_smoothup","Number of post-smoothing steps","SNESFASSetNumberSmoothUp",fas->max_up_it,&n_up,&upflg);
274: PetscOptionsInt("-snes_fas_smoothdown","Number of pre-smoothing steps","SNESFASSetNumberSmoothDown",fas->max_down_it,&n_down,&downflg);
276: {
277: PetscViewer viewer;
278: PetscViewerFormat format;
279: PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,
280: "-snes_fas_monitor",&viewer,&format,&monflg);
281: if (monflg) {
282: PetscViewerAndFormat *vf;
283: PetscViewerAndFormatCreate(viewer,format,&vf);
284: PetscObjectDereference((PetscObject)viewer);
285: SNESFASSetMonitor(snes,vf,PETSC_TRUE);
286: }
287: }
288: flg = PETSC_FALSE;
289: monflg = PETSC_TRUE;
290: PetscOptionsBool("-snes_fas_log","Log times for each FAS level","SNESFASSetLog",monflg,&monflg,&flg);
291: if (flg) {SNESFASSetLog(snes,monflg);}
292: }
294: PetscOptionsTail();
295: /* setup from the determined types if there is no pointwise procedure or smoother defined */
296: if (upflg) {
297: SNESFASSetNumberSmoothUp(snes,n_up);
298: }
299: if (downflg) {
300: SNESFASSetNumberSmoothDown(snes,n_down);
301: }
303: /* set up the default line search for coarse grid corrections */
304: if (fas->fastype == SNES_FAS_ADDITIVE) {
305: if (!snes->linesearch) {
306: SNESGetLineSearch(snes, &linesearch);
307: SNESLineSearchSetType(linesearch, SNESLINESEARCHL2);
308: }
309: }
311: SNESFASCycleGetCorrection(snes, &next);
312: /* recursive option setting for the smoothers */
313: if (next) {SNESSetFromOptions(next);}
314: return(0);
315: }
317: #include <petscdraw.h>
318: static PetscErrorCode SNESView_FAS(SNES snes, PetscViewer viewer)
319: {
320: SNES_FAS *fas = (SNES_FAS*) snes->data;
321: PetscBool isFine,iascii,isdraw;
322: PetscInt i;
324: SNES smoothu, smoothd, levelsnes;
327: SNESFASCycleIsFine(snes, &isFine);
328: if (isFine) {
329: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
330: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
331: if (iascii) {
332: PetscViewerASCIIPrintf(viewer, " type is %s, levels=%D, cycles=%D\n", SNESFASTypes[fas->fastype], fas->levels, fas->n_cycles);
333: if (fas->galerkin) {
334: PetscViewerASCIIPrintf(viewer," Using Galerkin computed coarse grid function evaluation\n");
335: } else {
336: PetscViewerASCIIPrintf(viewer," Not using Galerkin computed coarse grid function evaluation\n");
337: }
338: for (i=0; i<fas->levels; i++) {
339: SNESFASGetCycleSNES(snes, i, &levelsnes);
340: SNESFASCycleGetSmootherUp(levelsnes, &smoothu);
341: SNESFASCycleGetSmootherDown(levelsnes, &smoothd);
342: if (!i) {
343: PetscViewerASCIIPrintf(viewer," Coarse grid solver -- level %D -------------------------------\n",i);
344: } else {
345: PetscViewerASCIIPrintf(viewer," Down solver (pre-smoother) on level %D -------------------------------\n",i);
346: }
347: PetscViewerASCIIPushTab(viewer);
348: if (smoothd) {
349: SNESView(smoothd,viewer);
350: } else {
351: PetscViewerASCIIPrintf(viewer,"Not yet available\n");
352: }
353: PetscViewerASCIIPopTab(viewer);
354: if (i && (smoothd == smoothu)) {
355: PetscViewerASCIIPrintf(viewer," Up solver (post-smoother) same as down solver (pre-smoother)\n");
356: } else if (i) {
357: PetscViewerASCIIPrintf(viewer," Up solver (post-smoother) on level %D -------------------------------\n",i);
358: PetscViewerASCIIPushTab(viewer);
359: if (smoothu) {
360: SNESView(smoothu,viewer);
361: } else {
362: PetscViewerASCIIPrintf(viewer,"Not yet available\n");
363: }
364: PetscViewerASCIIPopTab(viewer);
365: }
366: }
367: } else if (isdraw) {
368: PetscDraw draw;
369: PetscReal x,w,y,bottom,th,wth;
370: SNES_FAS *curfas = fas;
371: PetscViewerDrawGetDraw(viewer,0,&draw);
372: PetscDrawGetCurrentPoint(draw,&x,&y);
373: PetscDrawStringGetSize(draw,&wth,&th);
374: bottom = y - th;
375: while (curfas) {
376: if (!curfas->smoothu) {
377: PetscDrawPushCurrentPoint(draw,x,bottom);
378: if (curfas->smoothd) SNESView(curfas->smoothd,viewer);
379: PetscDrawPopCurrentPoint(draw);
380: } else {
381: w = 0.5*PetscMin(1.0-x,x);
382: PetscDrawPushCurrentPoint(draw,x-w,bottom);
383: if (curfas->smoothd) SNESView(curfas->smoothd,viewer);
384: PetscDrawPopCurrentPoint(draw);
385: PetscDrawPushCurrentPoint(draw,x+w,bottom);
386: if (curfas->smoothu) SNESView(curfas->smoothu,viewer);
387: PetscDrawPopCurrentPoint(draw);
388: }
389: /* this is totally bogus but we have no way of knowing how low the previous one was draw to */
390: bottom -= 5*th;
391: if (curfas->next) curfas = (SNES_FAS*)curfas->next->data;
392: else curfas = NULL;
393: }
394: }
395: }
396: return(0);
397: }
399: /*
400: Defines the action of the downsmoother
401: */
402: static PetscErrorCode SNESFASDownSmooth_Private(SNES snes, Vec B, Vec X, Vec F, PetscReal *fnorm)
403: {
404: PetscErrorCode 0;
405: SNESConvergedReason reason;
406: Vec FPC;
407: SNES smoothd;
408: PetscBool flg;
409: SNES_FAS *fas = (SNES_FAS*) snes->data;
412: SNESFASCycleGetSmootherDown(snes, &smoothd);
413: SNESSetInitialFunction(smoothd, F);
414: if (fas->eventsmoothsolve) {PetscLogEventBegin(fas->eventsmoothsolve,smoothd,B,X,0);}
415: SNESSolve(smoothd, B, X);
416: if (fas->eventsmoothsolve) {PetscLogEventEnd(fas->eventsmoothsolve,smoothd,B,X,0);}
417: /* check convergence reason for the smoother */
418: SNESGetConvergedReason(smoothd,&reason);
419: if (reason < 0 && !(reason == SNES_DIVERGED_MAX_IT || reason == SNES_DIVERGED_LOCAL_MIN || reason == SNES_DIVERGED_LINE_SEARCH)) {
420: snes->reason = SNES_DIVERGED_INNER;
421: return(0);
422: }
424: SNESGetFunction(smoothd, &FPC, NULL, NULL);
425: SNESGetAlwaysComputesFinalResidual(smoothd, &flg);
426: if (!flg) {
427: SNESComputeFunction(smoothd, X, FPC);
428: }
429: VecCopy(FPC, F);
430: if (fnorm) {VecNorm(F,NORM_2,fnorm);}
431: return(0);
432: }
435: /*
436: Defines the action of the upsmoother
437: */
438: static PetscErrorCode SNESFASUpSmooth_Private(SNES snes, Vec B, Vec X, Vec F, PetscReal *fnorm)
439: {
440: PetscErrorCode 0;
441: SNESConvergedReason reason;
442: Vec FPC;
443: SNES smoothu;
444: PetscBool flg;
445: SNES_FAS *fas = (SNES_FAS*) snes->data;
448: SNESFASCycleGetSmootherUp(snes, &smoothu);
449: if (fas->eventsmoothsolve) {PetscLogEventBegin(fas->eventsmoothsolve,smoothu,0,0,0);}
450: SNESSolve(smoothu, B, X);
451: if (fas->eventsmoothsolve) {PetscLogEventEnd(fas->eventsmoothsolve,smoothu,0,0,0);}
452: /* check convergence reason for the smoother */
453: SNESGetConvergedReason(smoothu,&reason);
454: if (reason < 0 && !(reason == SNES_DIVERGED_MAX_IT || reason == SNES_DIVERGED_LOCAL_MIN || reason == SNES_DIVERGED_LINE_SEARCH)) {
455: snes->reason = SNES_DIVERGED_INNER;
456: return(0);
457: }
458: SNESGetFunction(smoothu, &FPC, NULL, NULL);
459: SNESGetAlwaysComputesFinalResidual(smoothu, &flg);
460: if (!flg) {
461: SNESComputeFunction(smoothu, X, FPC);
462: }
463: VecCopy(FPC, F);
464: if (fnorm) {VecNorm(F,NORM_2,fnorm);}
465: return(0);
466: }
468: /*@
469: SNESFASCreateCoarseVec - create Vec corresponding to a state vector on one level coarser than current level
471: Collective
473: Input Arguments:
474: . snes - SNESFAS
476: Output Arguments:
477: . Xcoarse - vector on level one coarser than snes
479: Level: developer
481: .seealso: SNESFASSetRestriction(), SNESFASRestrict()
482: @*/
483: PetscErrorCode SNESFASCreateCoarseVec(SNES snes,Vec *Xcoarse)
484: {
486: SNES_FAS *fas = (SNES_FAS*)snes->data;
489: if (fas->rscale) {
490: VecDuplicate(fas->rscale,Xcoarse);
491: } else if (fas->inject) {
492: MatCreateVecs(fas->inject,Xcoarse,NULL);
493: } else SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"Must set restriction or injection");
494: return(0);
495: }
497: /*@
498: SNESFASRestrict - restrict a Vec to the next coarser level
500: Collective
502: Input Arguments:
503: + fine - SNES from which to restrict
504: - Xfine - vector to restrict
506: Output Arguments:
507: . Xcoarse - result of restriction
509: Level: developer
511: .seealso: SNESFASSetRestriction(), SNESFASSetInjection()
512: @*/
513: PetscErrorCode SNESFASRestrict(SNES fine,Vec Xfine,Vec Xcoarse)
514: {
516: SNES_FAS *fas = (SNES_FAS*)fine->data;
522: if (fas->inject) {
523: MatRestrict(fas->inject,Xfine,Xcoarse);
524: } else {
525: MatRestrict(fas->restrct,Xfine,Xcoarse);
526: VecPointwiseMult(Xcoarse,fas->rscale,Xcoarse);
527: }
528: return(0);
529: }
531: /*
533: Performs the FAS coarse correction as:
535: fine problem: F(x) = b
536: coarse problem: F^c(x^c) = b^c
538: b^c = F^c(Rx) - R(F(x) - b)
540: */
541: PetscErrorCode SNESFASCoarseCorrection(SNES snes, Vec X, Vec F, Vec X_new)
542: {
543: PetscErrorCode ierr;
544: Vec X_c, Xo_c, F_c, B_c;
545: SNESConvergedReason reason;
546: SNES next;
547: Mat restrct, interpolate;
548: SNES_FAS *fasc;
551: SNESFASCycleGetCorrection(snes, &next);
552: if (next) {
553: fasc = (SNES_FAS*)next->data;
555: SNESFASCycleGetRestriction(snes, &restrct);
556: SNESFASCycleGetInterpolation(snes, &interpolate);
558: X_c = next->vec_sol;
559: Xo_c = next->work[0];
560: F_c = next->vec_func;
561: B_c = next->vec_rhs;
563: if (fasc->eventinterprestrict) {PetscLogEventBegin(fasc->eventinterprestrict,snes,0,0,0);}
564: SNESFASRestrict(snes, X, Xo_c);
565: /* restrict the defect: R(F(x) - b) */
566: MatRestrict(restrct, F, B_c);
567: if (fasc->eventinterprestrict) {PetscLogEventEnd(fasc->eventinterprestrict,snes,0,0,0);}
569: if (fasc->eventresidual) {PetscLogEventBegin(fasc->eventresidual,next,0,0,0);}
570: /* F_c = F^c(Rx) - R(F(x) - b) since the second term was sitting in next->vec_rhs */
571: SNESComputeFunction(next, Xo_c, F_c);
572: if (fasc->eventresidual) {PetscLogEventEnd(fasc->eventresidual,next,0,0,0);}
574: /* solve the coarse problem corresponding to F^c(x^c) = b^c = F^c(Rx) - R(F(x) - b) */
575: VecCopy(B_c, X_c);
576: VecCopy(F_c, B_c);
577: VecCopy(X_c, F_c);
578: /* set initial guess of the coarse problem to the projected fine solution */
579: VecCopy(Xo_c, X_c);
581: /* recurse to the next level */
582: SNESSetInitialFunction(next, F_c);
583: SNESSolve(next, B_c, X_c);
584: SNESGetConvergedReason(next,&reason);
585: if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
586: snes->reason = SNES_DIVERGED_INNER;
587: return(0);
588: }
589: /* correct as x <- x + I(x^c - Rx)*/
590: VecAXPY(X_c, -1.0, Xo_c);
592: if (fasc->eventinterprestrict) {PetscLogEventBegin(fasc->eventinterprestrict,snes,0,0,0);}
593: MatInterpolateAdd(interpolate, X_c, X, X_new);
594: PetscObjectSetName((PetscObject) X_c, "Coarse correction");
595: VecViewFromOptions(X_c, NULL, "-fas_coarse_solution_view");
596: PetscObjectSetName((PetscObject) X_new, "Updated Fine solution");
597: VecViewFromOptions(X_new, NULL, "-fas_levels_1_solution_view");
598: if (fasc->eventinterprestrict) {PetscLogEventEnd(fasc->eventinterprestrict,snes,0,0,0);}
599: }
600: return(0);
601: }
603: /*
605: The additive cycle looks like:
607: xhat = x
608: xhat = dS(x, b)
609: x = coarsecorrection(xhat, b_d)
610: x = x + nu*(xhat - x);
611: (optional) x = uS(x, b)
613: With the coarse RHS (defect correction) as below.
615: */
616: static PetscErrorCode SNESFASCycle_Additive(SNES snes, Vec X)
617: {
618: Vec F, B, Xhat;
619: Vec X_c, Xo_c, F_c, B_c;
620: PetscErrorCode ierr;
621: SNESConvergedReason reason;
622: PetscReal xnorm, fnorm, ynorm;
623: SNESLineSearchReason lsresult;
624: SNES next;
625: Mat restrct, interpolate;
626: SNES_FAS *fas = (SNES_FAS*)snes->data,*fasc;
629: SNESFASCycleGetCorrection(snes, &next);
630: F = snes->vec_func;
631: B = snes->vec_rhs;
632: Xhat = snes->work[1];
633: VecCopy(X, Xhat);
634: /* recurse first */
635: if (next) {
636: fasc = (SNES_FAS*)next->data;
637: SNESFASCycleGetRestriction(snes, &restrct);
638: SNESFASCycleGetInterpolation(snes, &interpolate);
639: if (fas->eventresidual) {PetscLogEventBegin(fas->eventresidual,snes,0,0,0);}
640: SNESComputeFunction(snes, Xhat, F);
641: if (fas->eventresidual) {PetscLogEventEnd(fas->eventresidual,snes,0,0,0);}
642: VecNorm(F, NORM_2, &fnorm);
643: X_c = next->vec_sol;
644: Xo_c = next->work[0];
645: F_c = next->vec_func;
646: B_c = next->vec_rhs;
648: SNESFASRestrict(snes,Xhat,Xo_c);
649: /* restrict the defect */
650: MatRestrict(restrct, F, B_c);
652: /* solve the coarse problem corresponding to F^c(x^c) = b^c = Rb + F^c(Rx) - RF(x) */
653: if (fasc->eventresidual) {PetscLogEventBegin(fasc->eventresidual,next,0,0,0);}
654: SNESComputeFunction(next, Xo_c, F_c);
655: if (fasc->eventresidual) {PetscLogEventEnd(fasc->eventresidual,next,0,0,0);}
656: VecCopy(B_c, X_c);
657: VecCopy(F_c, B_c);
658: VecCopy(X_c, F_c);
659: /* set initial guess of the coarse problem to the projected fine solution */
660: VecCopy(Xo_c, X_c);
662: /* recurse */
663: SNESSetInitialFunction(next, F_c);
664: SNESSolve(next, B_c, X_c);
666: /* smooth on this level */
667: SNESFASDownSmooth_Private(snes, B, X, F, &fnorm);
669: SNESGetConvergedReason(next,&reason);
670: if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
671: snes->reason = SNES_DIVERGED_INNER;
672: return(0);
673: }
675: /* correct as x <- x + I(x^c - Rx)*/
676: VecAYPX(X_c, -1.0, Xo_c);
677: MatInterpolate(interpolate, X_c, Xhat);
679: /* additive correction of the coarse direction*/
680: SNESLineSearchApply(snes->linesearch, X, F, &fnorm, Xhat);
681: SNESLineSearchGetReason(snes->linesearch, &lsresult);
682: SNESLineSearchGetNorms(snes->linesearch, &xnorm, &snes->norm, &ynorm);
683: if (lsresult) {
684: if (++snes->numFailures >= snes->maxFailures) {
685: snes->reason = SNES_DIVERGED_LINE_SEARCH;
686: return(0);
687: }
688: }
689: } else {
690: SNESFASDownSmooth_Private(snes, B, X, F, &snes->norm);
691: }
692: return(0);
693: }
695: /*
697: Defines the FAS cycle as:
699: fine problem: F(x) = b
700: coarse problem: F^c(x) = b^c
702: b^c = F^c(Rx) - R(F(x) - b)
704: correction:
706: x = x + I(x^c - Rx)
708: */
709: static PetscErrorCode SNESFASCycle_Multiplicative(SNES snes, Vec X)
710: {
713: Vec F,B;
714: SNES next;
717: F = snes->vec_func;
718: B = snes->vec_rhs;
719: /* pre-smooth -- just update using the pre-smoother */
720: SNESFASCycleGetCorrection(snes,&next);
721: SNESFASDownSmooth_Private(snes, B, X, F, &snes->norm);
722: if (next) {
723: SNESFASCoarseCorrection(snes, X, F, X);
724: SNESFASUpSmooth_Private(snes, B, X, F, &snes->norm);
725: }
726: return(0);
727: }
729: static PetscErrorCode SNESFASCycleSetupPhase_Full(SNES snes)
730: {
731: SNES next;
732: SNES_FAS *fas = (SNES_FAS*)snes->data;
733: PetscBool isFine;
737: /* pre-smooth -- just update using the pre-smoother */
738: SNESFASCycleIsFine(snes,&isFine);
739: SNESFASCycleGetCorrection(snes,&next);
740: fas->full_stage = 0;
741: if (next) {SNESFASCycleSetupPhase_Full(next);}
742: return(0);
743: }
745: static PetscErrorCode SNESFASCycle_Full(SNES snes, Vec X)
746: {
748: Vec F,B;
749: SNES_FAS *fas = (SNES_FAS*)snes->data;
750: PetscBool isFine;
751: SNES next;
754: F = snes->vec_func;
755: B = snes->vec_rhs;
756: SNESFASCycleIsFine(snes,&isFine);
757: SNESFASCycleGetCorrection(snes,&next);
759: if (isFine) {
760: SNESFASCycleSetupPhase_Full(snes);
761: }
763: if (fas->full_stage == 0) {
764: /* downsweep */
765: if (next) {
766: if (fas->level != 1) next->max_its += 1;
767: if (fas->full_downsweep||isFine) {SNESFASDownSmooth_Private(snes,B,X,F,&snes->norm);}
768: SNESFASCoarseCorrection(snes,X,F,X);
769: SNESFASUpSmooth_Private(snes,B,X,F,&snes->norm);
770: if (fas->level != 1) next->max_its -= 1;
771: } else {
772: /* The smoother on the coarse level is the coarse solver */
773: SNESFASDownSmooth_Private(snes,B,X,F,&snes->norm);
774: }
775: fas->full_stage = 1;
776: } else if (fas->full_stage == 1) {
777: if (snes->iter == 0) {SNESFASDownSmooth_Private(snes,B,X,F,&snes->norm);}
778: if (next) {
779: SNESFASCoarseCorrection(snes,X,F,X);
780: SNESFASUpSmooth_Private(snes,B,X,F,&snes->norm);
781: }
782: }
783: /* final v-cycle */
784: if (isFine) {
785: if (next) {
786: SNESFASCoarseCorrection(snes,X,F,X);
787: SNESFASUpSmooth_Private(snes,B,X,F,&snes->norm);
788: }
789: }
790: return(0);
791: }
793: static PetscErrorCode SNESFASCycle_Kaskade(SNES snes, Vec X)
794: {
796: Vec F,B;
797: SNES next;
800: F = snes->vec_func;
801: B = snes->vec_rhs;
802: SNESFASCycleGetCorrection(snes,&next);
803: if (next) {
804: SNESFASCoarseCorrection(snes,X,F,X);
805: SNESFASUpSmooth_Private(snes,B,X,F,&snes->norm);
806: } else {
807: SNESFASDownSmooth_Private(snes,B,X,F,&snes->norm);
808: }
809: return(0);
810: }
812: PetscBool SNEScite = PETSC_FALSE;
813: const char SNESCitation[] = "@techreport{pbmkbsxt2012,\n"
814: " title = {Composing Scalable Nonlinear Algebraic Solvers},\n"
815: " author = {Peter Brune and Mathew Knepley and Barry Smith and Xuemin Tu},\n"
816: " year = 2013,\n"
817: " type = Preprint,\n"
818: " number = {ANL/MCS-P2010-0112},\n"
819: " institution = {Argonne National Laboratory}\n}\n";
821: static PetscErrorCode SNESSolve_FAS(SNES snes)
822: {
824: PetscInt i, maxits;
825: Vec X, F;
826: PetscReal fnorm;
827: SNES_FAS *fas = (SNES_FAS*)snes->data,*ffas;
828: DM dm;
829: PetscBool isFine;
833: if (snes->xl || snes->xu || snes->ops->computevariablebounds) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE, "SNES solver %s does not support bounds", ((PetscObject)snes)->type_name);
835: PetscCitationsRegister(SNESCitation,&SNEScite);
836: maxits = snes->max_its; /* maximum number of iterations */
837: snes->reason = SNES_CONVERGED_ITERATING;
838: X = snes->vec_sol;
839: F = snes->vec_func;
841: SNESFASCycleIsFine(snes, &isFine);
842: /*norm setup */
843: PetscObjectSAWsTakeAccess((PetscObject)snes);
844: snes->iter = 0;
845: snes->norm = 0.;
846: PetscObjectSAWsGrantAccess((PetscObject)snes);
847: if (!snes->vec_func_init_set) {
848: if (fas->eventresidual) {PetscLogEventBegin(fas->eventresidual,snes,0,0,0);}
849: SNESComputeFunction(snes,X,F);
850: if (fas->eventresidual) {PetscLogEventEnd(fas->eventresidual,snes,0,0,0);}
851: } else snes->vec_func_init_set = PETSC_FALSE;
853: VecNorm(F, NORM_2, &fnorm); /* fnorm <- ||F|| */
854: SNESCheckFunctionNorm(snes,fnorm);
855: PetscObjectSAWsTakeAccess((PetscObject)snes);
856: snes->norm = fnorm;
857: PetscObjectSAWsGrantAccess((PetscObject)snes);
858: SNESLogConvergenceHistory(snes,fnorm,0);
859: SNESMonitor(snes,0,fnorm);
861: /* test convergence */
862: (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);
863: if (snes->reason) return(0);
866: if (isFine) {
867: /* propagate scale-dependent data up the hierarchy */
868: SNESGetDM(snes,&dm);
869: for (ffas=fas; ffas->next; ffas=(SNES_FAS*)ffas->next->data) {
870: DM dmcoarse;
871: SNESGetDM(ffas->next,&dmcoarse);
872: DMRestrict(dm,ffas->restrct,ffas->rscale,ffas->inject,dmcoarse);
873: dm = dmcoarse;
874: }
875: }
877: for (i = 0; i < maxits; i++) {
878: /* Call general purpose update function */
880: if (snes->ops->update) {
881: (*snes->ops->update)(snes, snes->iter);
882: }
883: if (fas->fastype == SNES_FAS_MULTIPLICATIVE) {
884: SNESFASCycle_Multiplicative(snes, X);
885: } else if (fas->fastype == SNES_FAS_ADDITIVE) {
886: SNESFASCycle_Additive(snes, X);
887: } else if (fas->fastype == SNES_FAS_FULL) {
888: SNESFASCycle_Full(snes, X);
889: } else if (fas->fastype ==SNES_FAS_KASKADE) {
890: SNESFASCycle_Kaskade(snes, X);
891: } else SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"Unsupported FAS type");
893: /* check for FAS cycle divergence */
894: if (snes->reason != SNES_CONVERGED_ITERATING) return(0);
896: /* Monitor convergence */
897: PetscObjectSAWsTakeAccess((PetscObject)snes);
898: snes->iter = i+1;
899: PetscObjectSAWsGrantAccess((PetscObject)snes);
900: SNESLogConvergenceHistory(snes,snes->norm,0);
901: SNESMonitor(snes,snes->iter,snes->norm);
902: /* Test for convergence */
903: if (isFine) {
904: (*snes->ops->converged)(snes,snes->iter,0.0,0.0,snes->norm,&snes->reason,snes->cnvP);
905: if (snes->reason) break;
906: }
907: }
908: if (i == maxits) {
909: PetscInfo1(snes, "Maximum number of iterations has been reached: %D\n", maxits);
910: if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT;
911: }
912: return(0);
913: }
915: /*MC
917: SNESFAS - Full Approximation Scheme nonlinear multigrid solver.
919: The nonlinear problem is solved by correction using coarse versions
920: of the nonlinear problem. This problem is perturbed so that a projected
921: solution of the fine problem elicits no correction from the coarse problem.
923: Options Database:
924: + -snes_fas_levels - The number of levels
925: . -snes_fas_cycles<1> - The number of cycles -- 1 for V, 2 for W
926: . -snes_fas_type<additive,multiplicative,full,kaskade> - Additive or multiplicative cycle
927: . -snes_fas_galerkin<PETSC_FALSE> - Form coarse problems by projection back upon the fine problem
928: . -snes_fas_smoothup<1> - The number of iterations of the post-smoother
929: . -snes_fas_smoothdown<1> - The number of iterations of the pre-smoother
930: . -snes_fas_monitor - Monitor progress of all of the levels
931: . -snes_fas_full_downsweep<PETSC_FALSE> - call the downsmooth on the initial downsweep of full FAS
932: . -fas_levels_snes_ - SNES options for all smoothers
933: . -fas_levels_cycle_snes_ - SNES options for all cycles
934: . -fas_levels_i_snes_ - SNES options for the smoothers on level i
935: . -fas_levels_i_cycle_snes_ - SNES options for the cycle on level i
936: - -fas_coarse_snes_ - SNES options for the coarsest smoother
938: Notes:
939: The organization of the FAS solver is slightly different from the organization of PCMG
940: As each level has smoother SNES instances(down and potentially up) and a cycle SNES instance.
941: The cycle SNES instance may be used for monitoring convergence on a particular level.
943: Level: beginner
945: References:
946: . 1. - Peter R. Brune, Matthew G. Knepley, Barry F. Smith, and Xuemin Tu, "Composing Scalable Nonlinear Algebraic Solvers",
947: SIAM Review, 57(4), 2015
949: .seealso: PCMG, SNESCreate(), SNES, SNESSetType(), SNESType (for list of available types)
950: M*/
952: PETSC_EXTERN PetscErrorCode SNESCreate_FAS(SNES snes)
953: {
954: SNES_FAS *fas;
958: snes->ops->destroy = SNESDestroy_FAS;
959: snes->ops->setup = SNESSetUp_FAS;
960: snes->ops->setfromoptions = SNESSetFromOptions_FAS;
961: snes->ops->view = SNESView_FAS;
962: snes->ops->solve = SNESSolve_FAS;
963: snes->ops->reset = SNESReset_FAS;
965: snes->usesksp = PETSC_FALSE;
966: snes->usesnpc = PETSC_FALSE;
968: if (!snes->tolerancesset) {
969: snes->max_funcs = 30000;
970: snes->max_its = 10000;
971: }
973: snes->alwayscomputesfinalresidual = PETSC_TRUE;
975: PetscNewLog(snes,&fas);
977: snes->data = (void*) fas;
978: fas->level = 0;
979: fas->levels = 1;
980: fas->n_cycles = 1;
981: fas->max_up_it = 1;
982: fas->max_down_it = 1;
983: fas->smoothu = NULL;
984: fas->smoothd = NULL;
985: fas->next = NULL;
986: fas->previous = NULL;
987: fas->fine = snes;
988: fas->interpolate = NULL;
989: fas->restrct = NULL;
990: fas->inject = NULL;
991: fas->usedmfornumberoflevels = PETSC_FALSE;
992: fas->fastype = SNES_FAS_MULTIPLICATIVE;
993: fas->full_downsweep = PETSC_FALSE;
995: fas->eventsmoothsetup = 0;
996: fas->eventsmoothsolve = 0;
997: fas->eventresidual = 0;
998: fas->eventinterprestrict = 0;
999: return(0);
1000: }