Actual source code: mg.c
1: /*
2: Defines the multigrid preconditioner interface.
3: */
4: #include <petsc/private/pcmgimpl.h>
5: #include <petsc/private/kspimpl.h>
6: #include <petscdm.h>
7: PETSC_INTERN PetscErrorCode PCPreSolveChangeRHS(PC, PetscBool *);
9: /*
10: Contains the list of registered coarse space construction routines
11: */
12: PetscFunctionList PCMGCoarseList = NULL;
14: PetscErrorCode PCMGMCycle_Private(PC pc, PC_MG_Levels **mglevelsin, PetscBool transpose, PetscBool matapp, PCRichardsonConvergedReason *reason)
15: {
16: PC_MG *mg = (PC_MG *)pc->data;
17: PC_MG_Levels *mgc, *mglevels = *mglevelsin;
18: PetscInt cycles = (mglevels->level == 1) ? 1 : mglevels->cycles;
20: PetscFunctionBegin;
21: if (mglevels->eventsmoothsolve) PetscCall(PetscLogEventBegin(mglevels->eventsmoothsolve, 0, 0, 0, 0));
22: if (!transpose) {
23: if (matapp) {
24: PetscCall(KSPMatSolve(mglevels->smoothd, mglevels->B, mglevels->X)); /* pre-smooth */
25: PetscCall(KSPCheckSolve(mglevels->smoothd, pc, NULL));
26: } else {
27: PetscCall(KSPSolve(mglevels->smoothd, mglevels->b, mglevels->x)); /* pre-smooth */
28: PetscCall(KSPCheckSolve(mglevels->smoothd, pc, mglevels->x));
29: }
30: } else {
31: PetscCheck(!matapp, PetscObjectComm((PetscObject)pc), PETSC_ERR_SUP, "Not supported");
32: PetscCall(KSPSolveTranspose(mglevels->smoothu, mglevels->b, mglevels->x)); /* transpose of post-smooth */
33: PetscCall(KSPCheckSolve(mglevels->smoothu, pc, mglevels->x));
34: }
35: if (mglevels->eventsmoothsolve) PetscCall(PetscLogEventEnd(mglevels->eventsmoothsolve, 0, 0, 0, 0));
36: if (mglevels->level) { /* not the coarsest grid */
37: if (mglevels->eventresidual) PetscCall(PetscLogEventBegin(mglevels->eventresidual, 0, 0, 0, 0));
38: if (matapp && !mglevels->R) PetscCall(MatDuplicate(mglevels->B, MAT_DO_NOT_COPY_VALUES, &mglevels->R));
39: if (!transpose) {
40: if (matapp) PetscCall((*mglevels->matresidual)(mglevels->A, mglevels->B, mglevels->X, mglevels->R));
41: else PetscCall((*mglevels->residual)(mglevels->A, mglevels->b, mglevels->x, mglevels->r));
42: } else {
43: if (matapp) PetscCall((*mglevels->matresidualtranspose)(mglevels->A, mglevels->B, mglevels->X, mglevels->R));
44: else PetscCall((*mglevels->residualtranspose)(mglevels->A, mglevels->b, mglevels->x, mglevels->r));
45: }
46: if (mglevels->eventresidual) PetscCall(PetscLogEventEnd(mglevels->eventresidual, 0, 0, 0, 0));
48: /* if on finest level and have convergence criteria set */
49: if (mglevels->level == mglevels->levels - 1 && mg->ttol && reason) {
50: PetscReal rnorm;
52: PetscCall(VecNorm(mglevels->r, NORM_2, &rnorm));
53: if (rnorm <= mg->ttol) {
54: if (rnorm < mg->abstol) {
55: *reason = PCRICHARDSON_CONVERGED_ATOL;
56: PetscCall(PetscInfo(pc, "Linear solver has converged. Residual norm %g is less than absolute tolerance %g\n", (double)rnorm, (double)mg->abstol));
57: } else {
58: *reason = PCRICHARDSON_CONVERGED_RTOL;
59: PetscCall(PetscInfo(pc, "Linear solver has converged. Residual norm %g is less than relative tolerance times initial residual norm %g\n", (double)rnorm, (double)mg->ttol));
60: }
61: PetscFunctionReturn(PETSC_SUCCESS);
62: }
63: }
65: mgc = *(mglevelsin - 1);
66: if (mglevels->eventinterprestrict) PetscCall(PetscLogEventBegin(mglevels->eventinterprestrict, 0, 0, 0, 0));
67: if (!transpose) {
68: if (matapp) PetscCall(MatMatRestrict(mglevels->restrct, mglevels->R, &mgc->B));
69: else PetscCall(MatRestrict(mglevels->restrct, mglevels->r, mgc->b));
70: } else {
71: if (matapp) PetscCall(MatMatRestrict(mglevels->interpolate, mglevels->R, &mgc->B));
72: else PetscCall(MatRestrict(mglevels->interpolate, mglevels->r, mgc->b));
73: }
74: if (mglevels->eventinterprestrict) PetscCall(PetscLogEventEnd(mglevels->eventinterprestrict, 0, 0, 0, 0));
75: if (matapp) {
76: if (!mgc->X) PetscCall(MatDuplicate(mgc->B, MAT_DO_NOT_COPY_VALUES, &mgc->X));
77: else {
78: PetscCall(MatZeroEntries(mgc->X));
79: }
80: } else {
81: PetscCall(VecZeroEntries(mgc->x));
82: }
83: while (cycles--) PetscCall(PCMGMCycle_Private(pc, mglevelsin - 1, transpose, matapp, reason));
84: if (mglevels->eventinterprestrict) PetscCall(PetscLogEventBegin(mglevels->eventinterprestrict, 0, 0, 0, 0));
85: if (!transpose) {
86: if (matapp) PetscCall(MatMatInterpolateAdd(mglevels->interpolate, mgc->X, mglevels->X, &mglevels->X));
87: else PetscCall(MatInterpolateAdd(mglevels->interpolate, mgc->x, mglevels->x, mglevels->x));
88: } else {
89: PetscCall(MatInterpolateAdd(mglevels->restrct, mgc->x, mglevels->x, mglevels->x));
90: }
91: if (mglevels->eventinterprestrict) PetscCall(PetscLogEventEnd(mglevels->eventinterprestrict, 0, 0, 0, 0));
92: if (mglevels->eventsmoothsolve) PetscCall(PetscLogEventBegin(mglevels->eventsmoothsolve, 0, 0, 0, 0));
93: if (!transpose) {
94: if (matapp) {
95: PetscCall(KSPMatSolve(mglevels->smoothu, mglevels->B, mglevels->X)); /* post smooth */
96: PetscCall(KSPCheckSolve(mglevels->smoothu, pc, NULL));
97: } else {
98: PetscCall(KSPSolve(mglevels->smoothu, mglevels->b, mglevels->x)); /* post smooth */
99: PetscCall(KSPCheckSolve(mglevels->smoothu, pc, mglevels->x));
100: }
101: } else {
102: PetscCheck(!matapp, PetscObjectComm((PetscObject)pc), PETSC_ERR_SUP, "Not supported");
103: PetscCall(KSPSolveTranspose(mglevels->smoothd, mglevels->b, mglevels->x)); /* post smooth */
104: PetscCall(KSPCheckSolve(mglevels->smoothd, pc, mglevels->x));
105: }
106: if (mglevels->cr) {
107: Mat crA;
109: PetscCheck(!matapp, PetscObjectComm((PetscObject)pc), PETSC_ERR_SUP, "Not supported");
110: /* TODO Turn on copy and turn off noisy if we have an exact solution
111: PetscCall(VecCopy(mglevels->x, mglevels->crx));
112: PetscCall(VecCopy(mglevels->b, mglevels->crb)); */
113: PetscCall(KSPGetOperators(mglevels->cr, &crA, NULL));
114: PetscCall(KSPSetNoisy_Private(crA, mglevels->crx));
115: PetscCall(KSPSolve(mglevels->cr, mglevels->crb, mglevels->crx)); /* compatible relaxation */
116: PetscCall(KSPCheckSolve(mglevels->cr, pc, mglevels->crx));
117: }
118: if (mglevels->eventsmoothsolve) PetscCall(PetscLogEventEnd(mglevels->eventsmoothsolve, 0, 0, 0, 0));
119: }
120: PetscFunctionReturn(PETSC_SUCCESS);
121: }
123: static PetscErrorCode PCApplyRichardson_MG(PC pc, Vec b, Vec x, Vec w, PetscReal rtol, PetscReal abstol, PetscReal dtol, PetscInt its, PetscBool zeroguess, PetscInt *outits, PCRichardsonConvergedReason *reason)
124: {
125: PC_MG *mg = (PC_MG *)pc->data;
126: PC_MG_Levels **mglevels = mg->levels;
127: PC tpc;
128: PetscBool changeu, changed;
129: PetscInt levels = mglevels[0]->levels, i;
131: PetscFunctionBegin;
132: /* When the DM is supplying the matrix then it will not exist until here */
133: for (i = 0; i < levels; i++) {
134: if (!mglevels[i]->A) {
135: PetscCall(KSPGetOperators(mglevels[i]->smoothu, &mglevels[i]->A, NULL));
136: PetscCall(PetscObjectReference((PetscObject)mglevels[i]->A));
137: }
138: }
140: PetscCall(KSPGetPC(mglevels[levels - 1]->smoothd, &tpc));
141: PetscCall(PCPreSolveChangeRHS(tpc, &changed));
142: PetscCall(KSPGetPC(mglevels[levels - 1]->smoothu, &tpc));
143: PetscCall(PCPreSolveChangeRHS(tpc, &changeu));
144: if (!changed && !changeu) {
145: PetscCall(VecDestroy(&mglevels[levels - 1]->b));
146: mglevels[levels - 1]->b = b;
147: } else { /* if the smoother changes the rhs during PreSolve, we cannot use the input vector */
148: if (!mglevels[levels - 1]->b) {
149: Vec *vec;
151: PetscCall(KSPCreateVecs(mglevels[levels - 1]->smoothd, 1, &vec, 0, NULL));
152: mglevels[levels - 1]->b = *vec;
153: PetscCall(PetscFree(vec));
154: }
155: PetscCall(VecCopy(b, mglevels[levels - 1]->b));
156: }
157: mglevels[levels - 1]->x = x;
159: mg->rtol = rtol;
160: mg->abstol = abstol;
161: mg->dtol = dtol;
162: if (rtol) {
163: /* compute initial residual norm for relative convergence test */
164: PetscReal rnorm;
166: if (zeroguess) {
167: PetscCall(VecNorm(b, NORM_2, &rnorm));
168: } else {
169: PetscCall((*mglevels[levels - 1]->residual)(mglevels[levels - 1]->A, b, x, w));
170: PetscCall(VecNorm(w, NORM_2, &rnorm));
171: }
172: mg->ttol = PetscMax(rtol * rnorm, abstol);
173: } else if (abstol) mg->ttol = abstol;
174: else mg->ttol = 0.0;
176: /* since smoother is applied to full system, not just residual we need to make sure that smoothers don't
177: stop prematurely due to small residual */
178: for (i = 1; i < levels; i++) {
179: PetscCall(KSPSetTolerances(mglevels[i]->smoothu, 0, PETSC_CURRENT, PETSC_CURRENT, PETSC_CURRENT));
180: if (mglevels[i]->smoothu != mglevels[i]->smoothd) {
181: /* For Richardson the initial guess is nonzero since it is solving in each cycle the original system not just applying as a preconditioner */
182: PetscCall(KSPSetInitialGuessNonzero(mglevels[i]->smoothd, PETSC_TRUE));
183: PetscCall(KSPSetTolerances(mglevels[i]->smoothd, 0, PETSC_CURRENT, PETSC_CURRENT, PETSC_CURRENT));
184: }
185: }
187: *reason = PCRICHARDSON_NOT_SET;
188: for (i = 0; i < its; i++) {
189: PetscCall(PCMGMCycle_Private(pc, mglevels + levels - 1, PETSC_FALSE, PETSC_FALSE, reason));
190: if (*reason) break;
191: }
192: if (*reason == PCRICHARDSON_NOT_SET) *reason = PCRICHARDSON_CONVERGED_ITS;
193: *outits = i;
194: if (!changed && !changeu) mglevels[levels - 1]->b = NULL;
195: PetscFunctionReturn(PETSC_SUCCESS);
196: }
198: PetscErrorCode PCReset_MG(PC pc)
199: {
200: PC_MG *mg = (PC_MG *)pc->data;
201: PC_MG_Levels **mglevels = mg->levels;
202: PetscInt i, n;
204: PetscFunctionBegin;
205: if (mglevels) {
206: n = mglevels[0]->levels;
207: for (i = 0; i < n - 1; i++) {
208: PetscCall(VecDestroy(&mglevels[i + 1]->r));
209: PetscCall(VecDestroy(&mglevels[i]->b));
210: PetscCall(VecDestroy(&mglevels[i]->x));
211: PetscCall(MatDestroy(&mglevels[i + 1]->R));
212: PetscCall(MatDestroy(&mglevels[i]->B));
213: PetscCall(MatDestroy(&mglevels[i]->X));
214: PetscCall(VecDestroy(&mglevels[i]->crx));
215: PetscCall(VecDestroy(&mglevels[i]->crb));
216: PetscCall(MatDestroy(&mglevels[i + 1]->restrct));
217: PetscCall(MatDestroy(&mglevels[i + 1]->interpolate));
218: PetscCall(MatDestroy(&mglevels[i + 1]->inject));
219: PetscCall(VecDestroy(&mglevels[i + 1]->rscale));
220: }
221: PetscCall(VecDestroy(&mglevels[n - 1]->crx));
222: PetscCall(VecDestroy(&mglevels[n - 1]->crb));
223: /* this is not null only if the smoother on the finest level
224: changes the rhs during PreSolve */
225: PetscCall(VecDestroy(&mglevels[n - 1]->b));
226: PetscCall(MatDestroy(&mglevels[n - 1]->B));
228: for (i = 0; i < n; i++) {
229: PetscCall(MatDestroy(&mglevels[i]->coarseSpace));
230: PetscCall(MatDestroy(&mglevels[i]->A));
231: if (mglevels[i]->smoothd != mglevels[i]->smoothu) PetscCall(KSPReset(mglevels[i]->smoothd));
232: PetscCall(KSPReset(mglevels[i]->smoothu));
233: if (mglevels[i]->cr) PetscCall(KSPReset(mglevels[i]->cr));
234: }
235: mg->Nc = 0;
236: }
237: PetscFunctionReturn(PETSC_SUCCESS);
238: }
240: /* Implementing CR
242: We only want to make corrections that ``do not change'' the coarse solution. What we mean by not changing is that if I prolong my coarse solution to the fine grid and then inject that fine solution back to the coarse grid, I get the same answer. Injection is what Brannick calls R. We want the complementary projector to Inj, which we will call S, after Brannick, so that Inj S = 0. Now the orthogonal projector onto the range of Inj^T is
244: Inj^T (Inj Inj^T)^{-1} Inj
246: and if Inj is a VecScatter, as it is now in PETSc, we have
248: Inj^T Inj
250: and
252: S = I - Inj^T Inj
254: since
256: Inj S = Inj - (Inj Inj^T) Inj = 0.
258: Brannick suggests
260: A \to S^T A S \qquad\mathrm{and}\qquad M \to S^T M S
262: but I do not think his :math:`S^T S = I` is correct. Our S is an orthogonal projector, so :math:`S^T S = S^2 = S`. We will use
264: M^{-1} A \to S M^{-1} A S
266: In fact, since it is somewhat hard in PETSc to do the symmetric application, we will just apply S on the left.
268: Check: || Inj P - I ||_F < tol
269: Check: In general, Inj Inj^T = I
270: */
272: typedef struct {
273: PC mg; /* The PCMG object */
274: PetscInt l; /* The multigrid level for this solver */
275: Mat Inj; /* The injection matrix */
276: Mat S; /* I - Inj^T Inj */
277: } CRContext;
279: static PetscErrorCode CRSetup_Private(PC pc)
280: {
281: CRContext *ctx;
282: Mat It;
284: PetscFunctionBeginUser;
285: PetscCall(PCShellGetContext(pc, &ctx));
286: PetscCall(PCMGGetInjection(ctx->mg, ctx->l, &It));
287: PetscCheck(It, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONGSTATE, "CR requires that injection be defined for this PCMG");
288: PetscCall(MatCreateTranspose(It, &ctx->Inj));
289: PetscCall(MatCreateNormal(ctx->Inj, &ctx->S));
290: PetscCall(MatScale(ctx->S, -1.0));
291: PetscCall(MatShift(ctx->S, 1.0));
292: PetscFunctionReturn(PETSC_SUCCESS);
293: }
295: static PetscErrorCode CRApply_Private(PC pc, Vec x, Vec y)
296: {
297: CRContext *ctx;
299: PetscFunctionBeginUser;
300: PetscCall(PCShellGetContext(pc, &ctx));
301: PetscCall(MatMult(ctx->S, x, y));
302: PetscFunctionReturn(PETSC_SUCCESS);
303: }
305: static PetscErrorCode CRDestroy_Private(PC pc)
306: {
307: CRContext *ctx;
309: PetscFunctionBeginUser;
310: PetscCall(PCShellGetContext(pc, &ctx));
311: PetscCall(MatDestroy(&ctx->Inj));
312: PetscCall(MatDestroy(&ctx->S));
313: PetscCall(PetscFree(ctx));
314: PetscCall(PCShellSetContext(pc, NULL));
315: PetscFunctionReturn(PETSC_SUCCESS);
316: }
318: static PetscErrorCode CreateCR_Private(PC pc, PetscInt l, PC *cr)
319: {
320: CRContext *ctx;
322: PetscFunctionBeginUser;
323: PetscCall(PCCreate(PetscObjectComm((PetscObject)pc), cr));
324: PetscCall(PetscObjectSetName((PetscObject)*cr, "S (complementary projector to injection)"));
325: PetscCall(PetscCalloc1(1, &ctx));
326: ctx->mg = pc;
327: ctx->l = l;
328: PetscCall(PCSetType(*cr, PCSHELL));
329: PetscCall(PCShellSetContext(*cr, ctx));
330: PetscCall(PCShellSetApply(*cr, CRApply_Private));
331: PetscCall(PCShellSetSetUp(*cr, CRSetup_Private));
332: PetscCall(PCShellSetDestroy(*cr, CRDestroy_Private));
333: PetscFunctionReturn(PETSC_SUCCESS);
334: }
336: PETSC_EXTERN PetscErrorCode PetscOptionsFindPairPrefix_Private(PetscOptions, const char[], const char[], const char *[], const char *[], PetscBool *);
338: PetscErrorCode PCMGSetLevels_MG(PC pc, PetscInt levels, MPI_Comm *comms)
339: {
340: PC_MG *mg = (PC_MG *)pc->data;
341: MPI_Comm comm;
342: PC_MG_Levels **mglevels = mg->levels;
343: PCMGType mgtype = mg->am;
344: PetscInt mgctype = (PetscInt)PC_MG_CYCLE_V;
345: PetscInt i;
346: PetscMPIInt size;
347: const char *prefix;
348: PC ipc;
349: PetscInt n;
351: PetscFunctionBegin;
354: if (mg->nlevels == levels) PetscFunctionReturn(PETSC_SUCCESS);
355: PetscCall(PetscObjectGetComm((PetscObject)pc, &comm));
356: if (mglevels) {
357: mgctype = mglevels[0]->cycles;
358: /* changing the number of levels so free up the previous stuff */
359: PetscCall(PCReset_MG(pc));
360: n = mglevels[0]->levels;
361: for (i = 0; i < n; i++) {
362: if (mglevels[i]->smoothd != mglevels[i]->smoothu) PetscCall(KSPDestroy(&mglevels[i]->smoothd));
363: PetscCall(KSPDestroy(&mglevels[i]->smoothu));
364: PetscCall(KSPDestroy(&mglevels[i]->cr));
365: PetscCall(PetscFree(mglevels[i]));
366: }
367: PetscCall(PetscFree(mg->levels));
368: }
370: mg->nlevels = levels;
372: PetscCall(PetscMalloc1(levels, &mglevels));
374: PetscCall(PCGetOptionsPrefix(pc, &prefix));
376: mg->stageApply = 0;
377: for (i = 0; i < levels; i++) {
378: PetscCall(PetscNew(&mglevels[i]));
380: mglevels[i]->level = i;
381: mglevels[i]->levels = levels;
382: mglevels[i]->cycles = mgctype;
383: mg->default_smoothu = 2;
384: mg->default_smoothd = 2;
385: mglevels[i]->eventsmoothsetup = 0;
386: mglevels[i]->eventsmoothsolve = 0;
387: mglevels[i]->eventresidual = 0;
388: mglevels[i]->eventinterprestrict = 0;
390: if (comms) comm = comms[i];
391: if (comm != MPI_COMM_NULL) {
392: PetscCall(KSPCreate(comm, &mglevels[i]->smoothd));
393: PetscCall(KSPSetNestLevel(mglevels[i]->smoothd, pc->kspnestlevel));
394: PetscCall(KSPSetErrorIfNotConverged(mglevels[i]->smoothd, pc->erroriffailure));
395: PetscCall(PetscObjectIncrementTabLevel((PetscObject)mglevels[i]->smoothd, (PetscObject)pc, levels - i));
396: PetscCall(KSPSetOptionsPrefix(mglevels[i]->smoothd, prefix));
397: PetscCall(PetscObjectComposedDataSetInt((PetscObject)mglevels[i]->smoothd, PetscMGLevelId, mglevels[i]->level));
398: if (i == 0 && levels > 1) { // coarse grid
399: PetscCall(KSPAppendOptionsPrefix(mglevels[0]->smoothd, "mg_coarse_"));
401: /* coarse solve is (redundant) LU by default; set shifttype NONZERO to avoid annoying zero-pivot in LU preconditioner */
402: PetscCall(KSPSetType(mglevels[0]->smoothd, KSPPREONLY));
403: PetscCall(KSPGetPC(mglevels[0]->smoothd, &ipc));
404: PetscCallMPI(MPI_Comm_size(comm, &size));
405: if (size > 1) PetscCall(PCSetType(ipc, PCREDUNDANT));
406: else PetscCall(PCSetType(ipc, PCLU));
407: PetscCall(PCFactorSetShiftType(ipc, MAT_SHIFT_INBLOCKS));
408: } else {
409: char tprefix[128];
411: PetscCall(KSPSetType(mglevels[i]->smoothd, KSPCHEBYSHEV));
412: PetscCall(KSPSetConvergenceTest(mglevels[i]->smoothd, KSPConvergedSkip, NULL, NULL));
413: PetscCall(KSPSetNormType(mglevels[i]->smoothd, KSP_NORM_NONE));
414: PetscCall(KSPGetPC(mglevels[i]->smoothd, &ipc));
415: PetscCall(PCSetType(ipc, PCSOR));
416: PetscCall(KSPSetTolerances(mglevels[i]->smoothd, PETSC_CURRENT, PETSC_CURRENT, PETSC_CURRENT, mg->default_smoothd));
418: if (i == levels - 1 && levels > 1) { // replace 'mg_finegrid_' with 'mg_levels_X_'
419: PetscBool set;
421: PetscCall(PetscOptionsFindPairPrefix_Private(((PetscObject)mglevels[i]->smoothd)->options, ((PetscObject)mglevels[i]->smoothd)->prefix, "-mg_fine_", NULL, NULL, &set));
422: if (set) {
423: if (prefix) PetscCall(PetscSNPrintf(tprefix, 128, "%smg_fine_", prefix));
424: else PetscCall(PetscSNPrintf(tprefix, 128, "mg_fine_"));
425: PetscCall(KSPSetOptionsPrefix(mglevels[i]->smoothd, tprefix));
426: } else {
427: PetscCall(PetscSNPrintf(tprefix, 128, "mg_levels_%" PetscInt_FMT "_", i));
428: PetscCall(KSPAppendOptionsPrefix(mglevels[i]->smoothd, tprefix));
429: }
430: } else {
431: PetscCall(PetscSNPrintf(tprefix, 128, "mg_levels_%" PetscInt_FMT "_", i));
432: PetscCall(KSPAppendOptionsPrefix(mglevels[i]->smoothd, tprefix));
433: }
434: }
435: }
436: mglevels[i]->smoothu = mglevels[i]->smoothd;
437: mg->rtol = 0.0;
438: mg->abstol = 0.0;
439: mg->dtol = 0.0;
440: mg->ttol = 0.0;
441: mg->cyclesperpcapply = 1;
442: }
443: mg->levels = mglevels;
444: PetscCall(PCMGSetType(pc, mgtype));
445: PetscFunctionReturn(PETSC_SUCCESS);
446: }
448: /*@C
449: PCMGSetLevels - Sets the number of levels to use with `PCMG`.
450: Must be called before any other `PCMG` routine.
452: Logically Collective
454: Input Parameters:
455: + pc - the preconditioner context
456: . levels - the number of levels
457: - comms - optional communicators for each level; this is to allow solving the coarser problems
458: on smaller sets of processes. For processes that are not included in the computation
459: you must pass `MPI_COMM_NULL`. Use comms = `NULL` to specify that all processes
460: should participate in each level of problem.
462: Options Database Key:
463: . -pc_mg_levels levels - set the number of levels to use
465: Level: intermediate
467: Notes:
468: If the number of levels is one then the multigrid uses the `-mg_levels` prefix
469: for setting the level options rather than the `-mg_coarse` or `-mg_fine` prefix.
471: You can free the information in comms after this routine is called.
473: The array of MPI communicators must contain `MPI_COMM_NULL` for those ranks that at each level
474: are not participating in the coarser solve. For example, with 2 levels and 1 and 2 ranks on
475: the two levels, rank 0 in the original communicator will pass in an array of 2 communicators
476: of size 2 and 1, while rank 1 in the original communicator will pass in array of 2 communicators
477: the first of size 2 and the second of value `MPI_COMM_NULL` since the rank 1 does not participate
478: in the coarse grid solve.
480: Since each coarser level may have a new `MPI_Comm` with fewer ranks than the previous, one
481: must take special care in providing the restriction and interpolation operation. We recommend
482: providing these as two step operations; first perform a standard restriction or interpolation on
483: the full number of ranks for that level and then use an MPI call to copy the resulting vector
484: array entries (after calls to VecGetArray()) to the smaller or larger number of ranks, note in both
485: cases the MPI calls must be made on the larger of the two communicators. Traditional MPI send and
486: receives or `MPI_AlltoAllv()` could be used to do the reshuffling of the vector entries.
488: Fortran Notes:
489: Use comms = `PETSC_NULL_MPI_COMM` as the equivalent of `NULL` in the C interface. Note `PETSC_NULL_MPI_COMM`
490: is not `MPI_COMM_NULL`. It is more like `PETSC_NULL_INTEGER`, `PETSC_NULL_REAL` etc.
492: .seealso: [](ch_ksp), `PCMGSetType()`, `PCMGGetLevels()`
493: @*/
494: PetscErrorCode PCMGSetLevels(PC pc, PetscInt levels, MPI_Comm *comms)
495: {
496: PetscFunctionBegin;
498: if (comms) PetscAssertPointer(comms, 3);
499: PetscTryMethod(pc, "PCMGSetLevels_C", (PC, PetscInt, MPI_Comm *), (pc, levels, comms));
500: PetscFunctionReturn(PETSC_SUCCESS);
501: }
503: PetscErrorCode PCDestroy_MG(PC pc)
504: {
505: PC_MG *mg = (PC_MG *)pc->data;
506: PC_MG_Levels **mglevels = mg->levels;
507: PetscInt i, n;
509: PetscFunctionBegin;
510: PetscCall(PCReset_MG(pc));
511: if (mglevels) {
512: n = mglevels[0]->levels;
513: for (i = 0; i < n; i++) {
514: if (mglevels[i]->smoothd != mglevels[i]->smoothu) PetscCall(KSPDestroy(&mglevels[i]->smoothd));
515: PetscCall(KSPDestroy(&mglevels[i]->smoothu));
516: PetscCall(KSPDestroy(&mglevels[i]->cr));
517: PetscCall(PetscFree(mglevels[i]));
518: }
519: PetscCall(PetscFree(mg->levels));
520: }
521: PetscCall(PetscFree(pc->data));
522: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCGetInterpolations_C", NULL));
523: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCGetCoarseOperators_C", NULL));
524: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGSetGalerkin_C", NULL));
525: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCSetReusePreconditioner_C", NULL));
526: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGGetLevels_C", NULL));
527: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGSetLevels_C", NULL));
528: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCGetInterpolations_C", NULL));
529: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCGetCoarseOperators_C", NULL));
530: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGSetAdaptInterpolation_C", NULL));
531: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGGetAdaptInterpolation_C", NULL));
532: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGSetAdaptCR_C", NULL));
533: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGGetAdaptCR_C", NULL));
534: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGSetAdaptCoarseSpaceType_C", NULL));
535: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGGetAdaptCoarseSpaceType_C", NULL));
536: PetscFunctionReturn(PETSC_SUCCESS);
537: }
539: /*
540: PCApply_MG - Runs either an additive, multiplicative, Kaskadic
541: or full cycle of multigrid.
543: Note:
544: A simple wrapper which calls PCMGMCycle(),PCMGACycle(), or PCMGFCycle().
545: */
546: static PetscErrorCode PCApply_MG_Internal(PC pc, Vec b, Vec x, Mat B, Mat X, PetscBool transpose)
547: {
548: PC_MG *mg = (PC_MG *)pc->data;
549: PC_MG_Levels **mglevels = mg->levels;
550: PC tpc;
551: PetscInt levels = mglevels[0]->levels, i;
552: PetscBool changeu, changed, matapp;
554: PetscFunctionBegin;
555: matapp = (PetscBool)(B && X);
556: if (mg->stageApply) PetscCall(PetscLogStagePush(mg->stageApply));
557: /* When the DM is supplying the matrix then it will not exist until here */
558: for (i = 0; i < levels; i++) {
559: if (!mglevels[i]->A) {
560: PetscCall(KSPGetOperators(mglevels[i]->smoothu, &mglevels[i]->A, NULL));
561: PetscCall(PetscObjectReference((PetscObject)mglevels[i]->A));
562: }
563: }
565: PetscCall(KSPGetPC(mglevels[levels - 1]->smoothd, &tpc));
566: PetscCall(PCPreSolveChangeRHS(tpc, &changed));
567: PetscCall(KSPGetPC(mglevels[levels - 1]->smoothu, &tpc));
568: PetscCall(PCPreSolveChangeRHS(tpc, &changeu));
569: if (!changeu && !changed) {
570: if (matapp) {
571: PetscCall(MatDestroy(&mglevels[levels - 1]->B));
572: mglevels[levels - 1]->B = B;
573: } else {
574: PetscCall(VecDestroy(&mglevels[levels - 1]->b));
575: mglevels[levels - 1]->b = b;
576: }
577: } else { /* if the smoother changes the rhs during PreSolve, we cannot use the input vector */
578: if (matapp) {
579: if (mglevels[levels - 1]->B) {
580: PetscInt N1, N2;
581: PetscBool flg;
583: PetscCall(MatGetSize(mglevels[levels - 1]->B, NULL, &N1));
584: PetscCall(MatGetSize(B, NULL, &N2));
585: PetscCall(PetscObjectTypeCompare((PetscObject)mglevels[levels - 1]->B, ((PetscObject)B)->type_name, &flg));
586: if (N1 != N2 || !flg) PetscCall(MatDestroy(&mglevels[levels - 1]->B));
587: }
588: if (!mglevels[levels - 1]->B) PetscCall(MatDuplicate(B, MAT_COPY_VALUES, &mglevels[levels - 1]->B));
589: else PetscCall(MatCopy(B, mglevels[levels - 1]->B, SAME_NONZERO_PATTERN));
590: } else {
591: if (!mglevels[levels - 1]->b) {
592: Vec *vec;
594: PetscCall(KSPCreateVecs(mglevels[levels - 1]->smoothd, 1, &vec, 0, NULL));
595: mglevels[levels - 1]->b = *vec;
596: PetscCall(PetscFree(vec));
597: }
598: PetscCall(VecCopy(b, mglevels[levels - 1]->b));
599: }
600: }
601: if (matapp) {
602: mglevels[levels - 1]->X = X;
603: } else {
604: mglevels[levels - 1]->x = x;
605: }
607: /* If coarser Xs are present, it means we have already block applied the PC at least once
608: Reset operators if sizes/type do no match */
609: if (matapp && levels > 1 && mglevels[levels - 2]->X) {
610: PetscInt Xc, Bc;
611: PetscBool flg;
613: PetscCall(MatGetSize(mglevels[levels - 2]->X, NULL, &Xc));
614: PetscCall(MatGetSize(mglevels[levels - 1]->B, NULL, &Bc));
615: PetscCall(PetscObjectTypeCompare((PetscObject)mglevels[levels - 2]->X, ((PetscObject)mglevels[levels - 1]->X)->type_name, &flg));
616: if (Xc != Bc || !flg) {
617: PetscCall(MatDestroy(&mglevels[levels - 1]->R));
618: for (i = 0; i < levels - 1; i++) {
619: PetscCall(MatDestroy(&mglevels[i]->R));
620: PetscCall(MatDestroy(&mglevels[i]->B));
621: PetscCall(MatDestroy(&mglevels[i]->X));
622: }
623: }
624: }
626: if (mg->am == PC_MG_MULTIPLICATIVE) {
627: if (matapp) PetscCall(MatZeroEntries(X));
628: else PetscCall(VecZeroEntries(x));
629: for (i = 0; i < mg->cyclesperpcapply; i++) PetscCall(PCMGMCycle_Private(pc, mglevels + levels - 1, transpose, matapp, NULL));
630: } else if (mg->am == PC_MG_ADDITIVE) {
631: PetscCall(PCMGACycle_Private(pc, mglevels, transpose, matapp));
632: } else if (mg->am == PC_MG_KASKADE) {
633: PetscCall(PCMGKCycle_Private(pc, mglevels, transpose, matapp));
634: } else {
635: PetscCall(PCMGFCycle_Private(pc, mglevels, transpose, matapp));
636: }
637: if (mg->stageApply) PetscCall(PetscLogStagePop());
638: if (!changeu && !changed) {
639: if (matapp) {
640: mglevels[levels - 1]->B = NULL;
641: } else {
642: mglevels[levels - 1]->b = NULL;
643: }
644: }
645: PetscFunctionReturn(PETSC_SUCCESS);
646: }
648: static PetscErrorCode PCApply_MG(PC pc, Vec b, Vec x)
649: {
650: PetscFunctionBegin;
651: PetscCall(PCApply_MG_Internal(pc, b, x, NULL, NULL, PETSC_FALSE));
652: PetscFunctionReturn(PETSC_SUCCESS);
653: }
655: static PetscErrorCode PCApplyTranspose_MG(PC pc, Vec b, Vec x)
656: {
657: PetscFunctionBegin;
658: PetscCall(PCApply_MG_Internal(pc, b, x, NULL, NULL, PETSC_TRUE));
659: PetscFunctionReturn(PETSC_SUCCESS);
660: }
662: static PetscErrorCode PCMatApply_MG(PC pc, Mat b, Mat x)
663: {
664: PetscFunctionBegin;
665: PetscCall(PCApply_MG_Internal(pc, NULL, NULL, b, x, PETSC_FALSE));
666: PetscFunctionReturn(PETSC_SUCCESS);
667: }
669: static PetscErrorCode PCMatApplyTranspose_MG(PC pc, Mat b, Mat x)
670: {
671: PetscFunctionBegin;
672: PetscCall(PCApply_MG_Internal(pc, NULL, NULL, b, x, PETSC_TRUE));
673: PetscFunctionReturn(PETSC_SUCCESS);
674: }
676: PetscErrorCode PCSetFromOptions_MG(PC pc, PetscOptionItems PetscOptionsObject)
677: {
678: PetscInt levels, cycles;
679: PetscBool flg, flg2;
680: PC_MG *mg = (PC_MG *)pc->data;
681: PC_MG_Levels **mglevels;
682: PCMGType mgtype;
683: PCMGCycleType mgctype;
684: PCMGGalerkinType gtype;
685: PCMGCoarseSpaceType coarseSpaceType;
687: PetscFunctionBegin;
688: levels = PetscMax(mg->nlevels, 1);
689: PetscOptionsHeadBegin(PetscOptionsObject, "Multigrid options");
690: PetscCall(PetscOptionsInt("-pc_mg_levels", "Number of Levels", "PCMGSetLevels", levels, &levels, &flg));
691: if (!flg && !mg->levels && pc->dm) {
692: PetscCall(DMGetRefineLevel(pc->dm, &levels));
693: levels++;
694: mg->usedmfornumberoflevels = PETSC_TRUE;
695: }
696: PetscCall(PCMGSetLevels(pc, levels, NULL));
697: mglevels = mg->levels;
699: mgctype = (PCMGCycleType)mglevels[0]->cycles;
700: PetscCall(PetscOptionsEnum("-pc_mg_cycle_type", "V cycle or for W-cycle", "PCMGSetCycleType", PCMGCycleTypes, (PetscEnum)mgctype, (PetscEnum *)&mgctype, &flg));
701: if (flg) PetscCall(PCMGSetCycleType(pc, mgctype));
702: coarseSpaceType = mg->coarseSpaceType;
703: PetscCall(PetscOptionsEnum("-pc_mg_adapt_interp_coarse_space", "Type of adaptive coarse space: none, polynomial, harmonic, eigenvector, generalized_eigenvector, gdsw", "PCMGSetAdaptCoarseSpaceType", PCMGCoarseSpaceTypes, (PetscEnum)coarseSpaceType, (PetscEnum *)&coarseSpaceType, &flg));
704: if (flg) PetscCall(PCMGSetAdaptCoarseSpaceType(pc, coarseSpaceType));
705: PetscCall(PetscOptionsInt("-pc_mg_adapt_interp_n", "Size of the coarse space for adaptive interpolation", "PCMGSetCoarseSpace", mg->Nc, &mg->Nc, &flg));
706: PetscCall(PetscOptionsBool("-pc_mg_mesp_monitor", "Monitor the multilevel eigensolver", "PCMGSetAdaptInterpolation", PETSC_FALSE, &mg->mespMonitor, &flg));
707: flg2 = PETSC_FALSE;
708: PetscCall(PetscOptionsBool("-pc_mg_adapt_cr", "Monitor coarse space quality using Compatible Relaxation (CR)", "PCMGSetAdaptCR", PETSC_FALSE, &flg2, &flg));
709: if (flg) PetscCall(PCMGSetAdaptCR(pc, flg2));
710: flg = PETSC_FALSE;
711: PetscCall(PetscOptionsBool("-pc_mg_distinct_smoothup", "Create separate smoothup KSP and append the prefix _up", "PCMGSetDistinctSmoothUp", PETSC_FALSE, &flg, NULL));
712: if (flg) PetscCall(PCMGSetDistinctSmoothUp(pc));
713: PetscCall(PetscOptionsEnum("-pc_mg_galerkin", "Use Galerkin process to compute coarser operators", "PCMGSetGalerkin", PCMGGalerkinTypes, (PetscEnum)mg->galerkin, (PetscEnum *)>ype, &flg));
714: if (flg) PetscCall(PCMGSetGalerkin(pc, gtype));
715: mgtype = mg->am;
716: PetscCall(PetscOptionsEnum("-pc_mg_type", "Multigrid type", "PCMGSetType", PCMGTypes, (PetscEnum)mgtype, (PetscEnum *)&mgtype, &flg));
717: if (flg) PetscCall(PCMGSetType(pc, mgtype));
718: if (mg->am == PC_MG_MULTIPLICATIVE) {
719: PetscCall(PetscOptionsInt("-pc_mg_multiplicative_cycles", "Number of cycles for each preconditioner step", "PCMGMultiplicativeSetCycles", mg->cyclesperpcapply, &cycles, &flg));
720: if (flg) PetscCall(PCMGMultiplicativeSetCycles(pc, cycles));
721: }
722: flg = PETSC_FALSE;
723: PetscCall(PetscOptionsBool("-pc_mg_log", "Log times for each multigrid level", "None", flg, &flg, NULL));
724: if (flg) {
725: PetscInt i;
726: char eventname[128];
728: levels = mglevels[0]->levels;
729: for (i = 0; i < levels; i++) {
730: PetscCall(PetscSNPrintf(eventname, PETSC_STATIC_ARRAY_LENGTH(eventname), "MGSetup Level %" PetscInt_FMT, i));
731: PetscCall(PetscLogEventRegister(eventname, ((PetscObject)pc)->classid, &mglevels[i]->eventsmoothsetup));
732: PetscCall(PetscSNPrintf(eventname, PETSC_STATIC_ARRAY_LENGTH(eventname), "MGSmooth Level %" PetscInt_FMT, i));
733: PetscCall(PetscLogEventRegister(eventname, ((PetscObject)pc)->classid, &mglevels[i]->eventsmoothsolve));
734: if (i) {
735: PetscCall(PetscSNPrintf(eventname, PETSC_STATIC_ARRAY_LENGTH(eventname), "MGResid Level %" PetscInt_FMT, i));
736: PetscCall(PetscLogEventRegister(eventname, ((PetscObject)pc)->classid, &mglevels[i]->eventresidual));
737: PetscCall(PetscSNPrintf(eventname, PETSC_STATIC_ARRAY_LENGTH(eventname), "MGInterp Level %" PetscInt_FMT, i));
738: PetscCall(PetscLogEventRegister(eventname, ((PetscObject)pc)->classid, &mglevels[i]->eventinterprestrict));
739: }
740: }
742: if (PetscDefined(USE_LOG)) {
743: const char sname[] = "MG Apply";
745: PetscCall(PetscLogStageGetId(sname, &mg->stageApply));
746: if (mg->stageApply < 0) PetscCall(PetscLogStageRegister(sname, &mg->stageApply));
747: }
748: }
749: PetscOptionsHeadEnd();
750: /* Check option consistency */
751: PetscCall(PCMGGetGalerkin(pc, >ype));
752: PetscCall(PCMGGetAdaptInterpolation(pc, &flg));
753: PetscCheck(!flg || !(gtype >= PC_MG_GALERKIN_NONE), PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_INCOMP, "Must use Galerkin coarse operators when adapting the interpolator");
754: PetscFunctionReturn(PETSC_SUCCESS);
755: }
757: const char *const PCMGTypes[] = {"MULTIPLICATIVE", "ADDITIVE", "FULL", "KASKADE", "PCMGType", "PC_MG", NULL};
758: const char *const PCMGCycleTypes[] = {"invalid", "v", "w", "PCMGCycleType", "PC_MG_CYCLE", NULL};
759: const char *const PCMGGalerkinTypes[] = {"both", "pmat", "mat", "none", "external", "PCMGGalerkinType", "PC_MG_GALERKIN", NULL};
760: const char *const PCMGCoarseSpaceTypes[] = {"none", "polynomial", "harmonic", "eigenvector", "generalized_eigenvector", "gdsw", "PCMGCoarseSpaceType", "PCMG_ADAPT_NONE", NULL};
762: #include <petscdraw.h>
763: PetscErrorCode PCView_MG(PC pc, PetscViewer viewer)
764: {
765: PC_MG *mg = (PC_MG *)pc->data;
766: PC_MG_Levels **mglevels = mg->levels;
767: PetscInt levels = mglevels ? mglevels[0]->levels : 0, i;
768: PetscBool isascii, isbinary, isdraw;
770: PetscFunctionBegin;
771: PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
772: PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
773: PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERDRAW, &isdraw));
774: if (isascii) {
775: const char *cyclename = levels ? (mglevels[0]->cycles == PC_MG_CYCLE_V ? "v" : "w") : "unknown";
777: if (levels == 1) PetscCall(PetscViewerASCIIPrintf(viewer, " WARNING: Multigrid is being run with only a single level!\n"));
778: PetscCall(PetscViewerASCIIPrintf(viewer, " type is %s, levels=%" PetscInt_FMT " cycles=%s\n", PCMGTypes[mg->am], levels, cyclename));
779: if (mg->am == PC_MG_MULTIPLICATIVE) PetscCall(PetscViewerASCIIPrintf(viewer, " Cycles per PCApply=%" PetscInt_FMT "\n", mg->cyclesperpcapply));
780: if (mg->galerkin == PC_MG_GALERKIN_BOTH) {
781: PetscCall(PetscViewerASCIIPrintf(viewer, " Using Galerkin computed coarse grid matrices\n"));
782: } else if (mg->galerkin == PC_MG_GALERKIN_PMAT) {
783: PetscCall(PetscViewerASCIIPrintf(viewer, " Using Galerkin computed coarse grid matrices for pmat\n"));
784: } else if (mg->galerkin == PC_MG_GALERKIN_MAT) {
785: PetscCall(PetscViewerASCIIPrintf(viewer, " Using Galerkin computed coarse grid matrices for mat\n"));
786: } else if (mg->galerkin == PC_MG_GALERKIN_EXTERNAL) {
787: PetscCall(PetscViewerASCIIPrintf(viewer, " Using externally compute Galerkin coarse grid matrices\n"));
788: } else {
789: PetscCall(PetscViewerASCIIPrintf(viewer, " Not using Galerkin computed coarse grid matrices\n"));
790: }
791: if (mg->view) PetscCall((*mg->view)(pc, viewer));
792: for (i = 0; i < levels; i++) {
793: if (i) {
794: PetscCall(PetscViewerASCIIPrintf(viewer, "Down solver (pre-smoother) on level %" PetscInt_FMT " -------------------------------\n", i));
795: } else {
796: PetscCall(PetscViewerASCIIPrintf(viewer, "Coarse grid solver -- level %" PetscInt_FMT " -------------------------------\n", i));
797: }
798: PetscCall(PetscViewerASCIIPushTab(viewer));
799: PetscCall(KSPView(mglevels[i]->smoothd, viewer));
800: PetscCall(PetscViewerASCIIPopTab(viewer));
801: if (i && mglevels[i]->smoothd == mglevels[i]->smoothu) {
802: PetscCall(PetscViewerASCIIPrintf(viewer, "Up solver (post-smoother) same as down solver (pre-smoother)\n"));
803: } else if (i) {
804: PetscCall(PetscViewerASCIIPrintf(viewer, "Up solver (post-smoother) on level %" PetscInt_FMT " -------------------------------\n", i));
805: PetscCall(PetscViewerASCIIPushTab(viewer));
806: PetscCall(KSPView(mglevels[i]->smoothu, viewer));
807: PetscCall(PetscViewerASCIIPopTab(viewer));
808: }
809: if (i && mglevels[i]->cr) {
810: PetscCall(PetscViewerASCIIPrintf(viewer, "CR solver on level %" PetscInt_FMT " -------------------------------\n", i));
811: PetscCall(PetscViewerASCIIPushTab(viewer));
812: PetscCall(KSPView(mglevels[i]->cr, viewer));
813: PetscCall(PetscViewerASCIIPopTab(viewer));
814: }
815: }
816: } else if (isbinary) {
817: for (i = levels - 1; i >= 0; i--) {
818: PetscCall(KSPView(mglevels[i]->smoothd, viewer));
819: if (i && mglevels[i]->smoothd != mglevels[i]->smoothu) PetscCall(KSPView(mglevels[i]->smoothu, viewer));
820: }
821: } else if (isdraw) {
822: PetscDraw draw;
823: PetscReal x, w, y, bottom, th;
824: PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
825: PetscCall(PetscDrawGetCurrentPoint(draw, &x, &y));
826: PetscCall(PetscDrawStringGetSize(draw, NULL, &th));
827: bottom = y - th;
828: for (i = levels - 1; i >= 0; i--) {
829: if (!mglevels[i]->smoothu || (mglevels[i]->smoothu == mglevels[i]->smoothd)) {
830: PetscCall(PetscDrawPushCurrentPoint(draw, x, bottom));
831: PetscCall(KSPView(mglevels[i]->smoothd, viewer));
832: PetscCall(PetscDrawPopCurrentPoint(draw));
833: } else {
834: w = 0.5 * PetscMin(1.0 - x, x);
835: PetscCall(PetscDrawPushCurrentPoint(draw, x + w, bottom));
836: PetscCall(KSPView(mglevels[i]->smoothd, viewer));
837: PetscCall(PetscDrawPopCurrentPoint(draw));
838: PetscCall(PetscDrawPushCurrentPoint(draw, x - w, bottom));
839: PetscCall(KSPView(mglevels[i]->smoothu, viewer));
840: PetscCall(PetscDrawPopCurrentPoint(draw));
841: }
842: PetscCall(PetscDrawGetBoundingBox(draw, NULL, &bottom, NULL, NULL));
843: bottom -= th;
844: }
845: }
846: PetscFunctionReturn(PETSC_SUCCESS);
847: }
849: #include <petsc/private/kspimpl.h>
851: /*
852: Calls setup for the KSP on each level
853: */
854: PetscErrorCode PCSetUp_MG(PC pc)
855: {
856: PC_MG *mg = (PC_MG *)pc->data;
857: PC_MG_Levels **mglevels = mg->levels;
858: PetscInt n;
859: PC cpc;
860: PetscBool dump = PETSC_FALSE, opsset, use_amat, missinginterpolate = PETSC_FALSE;
861: Mat dA, dB;
862: Vec tvec;
863: DM *dms;
864: PetscViewer viewer = NULL;
865: PetscBool dAeqdB = PETSC_FALSE, needRestricts = PETSC_FALSE, doCR = PETSC_FALSE;
866: PetscBool adaptInterpolation = mg->adaptInterpolation;
868: PetscFunctionBegin;
869: PetscCheck(mglevels, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONGSTATE, "Must set MG levels with PCMGSetLevels() before setting up");
870: n = mglevels[0]->levels;
871: /* FIX: Move this to PCSetFromOptions_MG? */
872: if (mg->usedmfornumberoflevels) {
873: PetscInt levels;
875: PetscCall(DMGetRefineLevel(pc->dm, &levels));
876: levels++;
877: if (levels > n) { /* the problem is now being solved on a finer grid */
878: PetscCall(PCMGSetLevels(pc, levels, NULL));
879: n = levels;
880: PetscCall(PCSetFromOptions(pc)); /* it is bad to call this here, but otherwise will never be called for the new hierarchy */
881: mglevels = mg->levels;
882: }
883: }
885: /* If user did not provide fine grid operators OR operator was not updated since last global KSPSetOperators() */
886: /* so use those from global PC */
887: /* Is this what we always want? What if user wants to keep old one? */
888: PetscCall(KSPGetOperatorsSet(mglevels[n - 1]->smoothd, NULL, &opsset));
889: if (opsset) {
890: Mat mmat;
891: PetscCall(KSPGetOperators(mglevels[n - 1]->smoothd, NULL, &mmat));
892: if (mmat == pc->pmat) opsset = PETSC_FALSE;
893: }
894: /* fine grid smoother inherits the reuse-pc flag */
895: PetscCall(KSPGetPC(mglevels[n - 1]->smoothd, &cpc));
896: cpc->reusepreconditioner = pc->reusepreconditioner;
897: PetscCall(KSPGetPC(mglevels[n - 1]->smoothu, &cpc));
898: cpc->reusepreconditioner = pc->reusepreconditioner;
900: /* Create CR solvers */
901: PetscCall(PCMGGetAdaptCR(pc, &doCR));
902: if (doCR) {
903: const char *prefix;
905: PetscCall(PCGetOptionsPrefix(pc, &prefix));
906: for (PetscInt i = 1; i < n; ++i) {
907: PC ipc, cr;
908: char crprefix[128];
910: PetscCall(KSPCreate(PetscObjectComm((PetscObject)pc), &mglevels[i]->cr));
911: PetscCall(KSPSetNestLevel(mglevels[i]->cr, pc->kspnestlevel));
912: PetscCall(KSPSetErrorIfNotConverged(mglevels[i]->cr, PETSC_FALSE));
913: PetscCall(PetscObjectIncrementTabLevel((PetscObject)mglevels[i]->cr, (PetscObject)pc, n - i));
914: PetscCall(KSPSetOptionsPrefix(mglevels[i]->cr, prefix));
915: PetscCall(PetscObjectComposedDataSetInt((PetscObject)mglevels[i]->cr, PetscMGLevelId, mglevels[i]->level));
916: PetscCall(KSPSetType(mglevels[i]->cr, KSPCHEBYSHEV));
917: PetscCall(KSPSetConvergenceTest(mglevels[i]->cr, KSPConvergedSkip, NULL, NULL));
918: PetscCall(KSPSetNormType(mglevels[i]->cr, KSP_NORM_PRECONDITIONED));
919: PetscCall(KSPGetPC(mglevels[i]->cr, &ipc));
921: PetscCall(PCSetType(ipc, PCCOMPOSITE));
922: PetscCall(PCCompositeSetType(ipc, PC_COMPOSITE_MULTIPLICATIVE));
923: PetscCall(PCCompositeAddPCType(ipc, PCSOR));
924: PetscCall(CreateCR_Private(pc, i, &cr));
925: PetscCall(PCCompositeAddPC(ipc, cr));
926: PetscCall(PCDestroy(&cr));
928: PetscCall(KSPSetTolerances(mglevels[i]->cr, PETSC_CURRENT, PETSC_CURRENT, PETSC_CURRENT, mg->default_smoothd));
929: PetscCall(KSPSetInitialGuessNonzero(mglevels[i]->cr, PETSC_TRUE));
930: PetscCall(PetscSNPrintf(crprefix, 128, "mg_levels_%" PetscInt_FMT "_cr_", i));
931: PetscCall(KSPAppendOptionsPrefix(mglevels[i]->cr, crprefix));
932: }
933: }
935: if (!opsset) {
936: PetscCall(PCGetUseAmat(pc, &use_amat));
937: if (use_amat) {
938: PetscCall(PetscInfo(pc, "Using outer operators to define finest grid operator \n because PCMGGetSmoother(pc,nlevels-1,&ksp);KSPSetOperators(ksp,...); was not called.\n"));
939: PetscCall(KSPSetOperators(mglevels[n - 1]->smoothd, pc->mat, pc->pmat));
940: } else {
941: PetscCall(PetscInfo(pc, "Using matrix (pmat) operators to define finest grid operator \n because PCMGGetSmoother(pc,nlevels-1,&ksp);KSPSetOperators(ksp,...); was not called.\n"));
942: PetscCall(KSPSetOperators(mglevels[n - 1]->smoothd, pc->pmat, pc->pmat));
943: }
944: }
946: for (PetscInt i = n - 1; i > 0; i--) {
947: if (!(mglevels[i]->interpolate || mglevels[i]->restrct)) {
948: missinginterpolate = PETSC_TRUE;
949: break;
950: }
951: }
953: PetscCall(KSPGetOperators(mglevels[n - 1]->smoothd, &dA, &dB));
954: if (dA == dB) dAeqdB = PETSC_TRUE;
955: if (mg->galerkin == PC_MG_GALERKIN_NONE || ((mg->galerkin == PC_MG_GALERKIN_PMAT || mg->galerkin == PC_MG_GALERKIN_MAT) && !dAeqdB)) needRestricts = PETSC_TRUE; /* user must compute either mat, pmat, or both so must restrict x to coarser levels */
957: if (pc->dm && !pc->setupcalled) {
958: /* finest smoother also gets DM but it is not active, independent of whether galerkin==PC_MG_GALERKIN_EXTERNAL */
959: PetscCall(KSPSetDM(mglevels[n - 1]->smoothd, pc->dm));
960: PetscCall(KSPSetDMActive(mglevels[n - 1]->smoothd, KSP_DMACTIVE_ALL, PETSC_FALSE));
961: if (mglevels[n - 1]->smoothd != mglevels[n - 1]->smoothu) {
962: PetscCall(KSPSetDM(mglevels[n - 1]->smoothu, pc->dm));
963: PetscCall(KSPSetDMActive(mglevels[n - 1]->smoothu, KSP_DMACTIVE_ALL, PETSC_FALSE));
964: }
965: if (mglevels[n - 1]->cr) {
966: PetscCall(KSPSetDM(mglevels[n - 1]->cr, pc->dm));
967: PetscCall(KSPSetDMActive(mglevels[n - 1]->cr, KSP_DMACTIVE_ALL, PETSC_FALSE));
968: }
969: }
971: /*
972: Skipping if user has provided all interpolation/restriction needed (since DM might not be able to produce them (when coming from SNES/TS)
973: Skipping for externally managed hierarchy (such as ML and GAMG). Cleaner logic here would be great. Wrap ML/GAMG as DMs?
974: */
975: if (missinginterpolate && mg->galerkin != PC_MG_GALERKIN_EXTERNAL && !pc->setupcalled) {
976: /* first see if we can compute a coarse space */
977: if (mg->coarseSpaceType == PCMG_ADAPT_GDSW) {
978: for (PetscInt i = n - 2; i > -1; i--) {
979: if (!mglevels[i + 1]->restrct && !mglevels[i + 1]->interpolate) {
980: PetscCall(PCMGComputeCoarseSpace_Internal(pc, i + 1, mg->coarseSpaceType, mg->Nc, NULL, &mglevels[i + 1]->coarseSpace));
981: PetscCall(PCMGSetInterpolation(pc, i + 1, mglevels[i + 1]->coarseSpace));
982: }
983: }
984: } else { /* construct the interpolation from the DMs */
985: Mat p;
986: Vec rscale;
988: PetscCheck(n == 1 || pc->dm, PetscObjectComm((PetscObject)pc), PETSC_ERR_SUP, "PC lacks a DM so cannot automatically construct a multigrid hierarchy. Number of levels requested %" PetscInt_FMT, n);
989: PetscCall(PetscMalloc1(n, &dms));
990: dms[n - 1] = pc->dm;
991: /* Separately create them so we do not get DMKSP interference between levels */
992: for (PetscInt i = n - 2; i > -1; i--) PetscCall(DMCoarsen(dms[i + 1], MPI_COMM_NULL, &dms[i]));
993: for (PetscInt i = n - 2; i > -1; i--) {
994: PetscBool dmhasrestrict, dmhasinject;
996: PetscCall(KSPSetDM(mglevels[i]->smoothd, dms[i]));
997: if (!needRestricts) PetscCall(KSPSetDMActive(mglevels[i]->smoothd, KSP_DMACTIVE_ALL, PETSC_FALSE));
998: PetscCall(KSPSetDMActive(mglevels[i]->smoothd, KSP_DMACTIVE_RHS, PETSC_FALSE));
999: if (mglevels[i]->smoothd != mglevels[i]->smoothu) {
1000: PetscCall(KSPSetDM(mglevels[i]->smoothu, dms[i]));
1001: if (!needRestricts) PetscCall(KSPSetDMActive(mglevels[i]->smoothu, KSP_DMACTIVE_ALL, PETSC_FALSE));
1002: PetscCall(KSPSetDMActive(mglevels[i]->smoothu, KSP_DMACTIVE_RHS, PETSC_FALSE));
1003: }
1004: if (mglevels[i]->cr) {
1005: PetscCall(KSPSetDM(mglevels[i]->cr, dms[i]));
1006: if (!needRestricts) PetscCall(KSPSetDMActive(mglevels[i]->cr, KSP_DMACTIVE_ALL, PETSC_FALSE));
1007: PetscCall(KSPSetDMActive(mglevels[i]->cr, KSP_DMACTIVE_RHS, PETSC_FALSE));
1008: }
1009: if (!mglevels[i + 1]->interpolate) {
1010: PetscCall(DMCreateInterpolation(dms[i], dms[i + 1], &p, &rscale));
1011: PetscCall(PCMGSetInterpolation(pc, i + 1, p));
1012: if (rscale) PetscCall(PCMGSetRScale(pc, i + 1, rscale));
1013: PetscCall(VecDestroy(&rscale));
1014: PetscCall(MatDestroy(&p));
1015: }
1016: PetscCall(DMHasCreateRestriction(dms[i], &dmhasrestrict));
1017: if (dmhasrestrict && !mglevels[i + 1]->restrct) {
1018: PetscCall(DMCreateRestriction(dms[i], dms[i + 1], &p));
1019: PetscCall(PCMGSetRestriction(pc, i + 1, p));
1020: PetscCall(MatDestroy(&p));
1021: }
1022: PetscCall(DMHasCreateInjection(dms[i], &dmhasinject));
1023: if (dmhasinject && !mglevels[i + 1]->inject) {
1024: PetscCall(DMCreateInjection(dms[i], dms[i + 1], &p));
1025: PetscCall(PCMGSetInjection(pc, i + 1, p));
1026: PetscCall(MatDestroy(&p));
1027: }
1028: }
1030: for (PetscInt i = n - 2; i > -1; i--) PetscCall(DMDestroy(&dms[i]));
1031: PetscCall(PetscFree(dms));
1032: }
1033: }
1035: if (mg->galerkin < PC_MG_GALERKIN_NONE) {
1036: Mat A, B;
1037: PetscBool doA = PETSC_FALSE, doB = PETSC_FALSE;
1038: MatReuse reuse = MAT_INITIAL_MATRIX;
1040: if (mg->galerkin == PC_MG_GALERKIN_PMAT || mg->galerkin == PC_MG_GALERKIN_BOTH) doB = PETSC_TRUE;
1041: if (mg->galerkin == PC_MG_GALERKIN_MAT || (mg->galerkin == PC_MG_GALERKIN_BOTH && dA != dB)) doA = PETSC_TRUE;
1042: if (pc->setupcalled) reuse = MAT_REUSE_MATRIX;
1043: for (PetscInt i = n - 2; i > -1; i--) {
1044: PetscCheck(mglevels[i + 1]->restrct || mglevels[i + 1]->interpolate, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONGSTATE, "Must provide interpolation or restriction for each MG level except level 0");
1045: if (!mglevels[i + 1]->interpolate) PetscCall(PCMGSetInterpolation(pc, i + 1, mglevels[i + 1]->restrct));
1046: if (!mglevels[i + 1]->restrct) PetscCall(PCMGSetRestriction(pc, i + 1, mglevels[i + 1]->interpolate));
1047: if (reuse == MAT_REUSE_MATRIX) PetscCall(KSPGetOperators(mglevels[i]->smoothd, &A, &B));
1048: if (doA) PetscCall(MatGalerkin(mglevels[i + 1]->restrct, dA, mglevels[i + 1]->interpolate, reuse, 1.0, &A));
1049: if (doB) PetscCall(MatGalerkin(mglevels[i + 1]->restrct, dB, mglevels[i + 1]->interpolate, reuse, 1.0, &B));
1050: /* the management of the PetscObjectReference() and PetscObjecDereference() below is rather delicate */
1051: if (!doA && dAeqdB) {
1052: if (reuse == MAT_INITIAL_MATRIX) PetscCall(PetscObjectReference((PetscObject)B));
1053: A = B;
1054: } else if (!doA && reuse == MAT_INITIAL_MATRIX) {
1055: PetscCall(KSPGetOperators(mglevels[i]->smoothd, &A, NULL));
1056: PetscCall(PetscObjectReference((PetscObject)A));
1057: }
1058: if (!doB && dAeqdB) {
1059: if (reuse == MAT_INITIAL_MATRIX) PetscCall(PetscObjectReference((PetscObject)A));
1060: B = A;
1061: } else if (!doB && reuse == MAT_INITIAL_MATRIX) {
1062: PetscCall(KSPGetOperators(mglevels[i]->smoothd, NULL, &B));
1063: PetscCall(PetscObjectReference((PetscObject)B));
1064: }
1065: if (reuse == MAT_INITIAL_MATRIX) {
1066: PetscCall(KSPSetOperators(mglevels[i]->smoothd, A, B));
1067: PetscCall(PetscObjectDereference((PetscObject)A));
1068: PetscCall(PetscObjectDereference((PetscObject)B));
1069: }
1070: dA = A;
1071: dB = B;
1072: }
1073: }
1075: /* Adapt interpolation matrices */
1076: if (adaptInterpolation) {
1077: for (PetscInt i = 0; i < n; ++i) {
1078: if (!mglevels[i]->coarseSpace) PetscCall(PCMGComputeCoarseSpace_Internal(pc, i, mg->coarseSpaceType, mg->Nc, !i ? NULL : mglevels[i - 1]->coarseSpace, &mglevels[i]->coarseSpace));
1079: if (i) PetscCall(PCMGAdaptInterpolator_Internal(pc, i, mglevels[i - 1]->smoothu, mglevels[i]->smoothu, mglevels[i - 1]->coarseSpace, mglevels[i]->coarseSpace));
1080: }
1081: for (PetscInt i = n - 2; i > -1; --i) PetscCall(PCMGRecomputeLevelOperators_Internal(pc, i));
1082: }
1084: if (needRestricts && pc->dm) {
1085: for (PetscInt i = n - 2; i >= 0; i--) {
1086: DM dmfine, dmcoarse;
1087: Mat Restrict, Inject;
1088: Vec rscale;
1090: PetscCall(KSPGetDM(mglevels[i + 1]->smoothd, &dmfine));
1091: PetscCall(KSPGetDM(mglevels[i]->smoothd, &dmcoarse));
1092: PetscCall(PCMGGetRestriction(pc, i + 1, &Restrict));
1093: PetscCall(PCMGGetRScale(pc, i + 1, &rscale));
1094: PetscCall(PCMGGetInjection(pc, i + 1, &Inject));
1095: PetscCall(DMRestrict(dmfine, Restrict, rscale, Inject, dmcoarse));
1096: }
1097: }
1099: if (!pc->setupcalled) {
1100: for (PetscInt i = 0; i < n; i++) PetscCall(KSPSetFromOptions(mglevels[i]->smoothd));
1101: for (PetscInt i = 1; i < n; i++) {
1102: if (mglevels[i]->smoothu && (mglevels[i]->smoothu != mglevels[i]->smoothd)) PetscCall(KSPSetFromOptions(mglevels[i]->smoothu));
1103: if (mglevels[i]->cr) PetscCall(KSPSetFromOptions(mglevels[i]->cr));
1104: }
1105: /* insure that if either interpolation or restriction is set the other one is set */
1106: for (PetscInt i = 1; i < n; i++) {
1107: PetscCall(PCMGGetInterpolation(pc, i, NULL));
1108: PetscCall(PCMGGetRestriction(pc, i, NULL));
1109: }
1110: for (PetscInt i = 0; i < n - 1; i++) {
1111: if (!mglevels[i]->b) {
1112: Vec *vec;
1113: PetscCall(KSPCreateVecs(mglevels[i]->smoothd, 1, &vec, 0, NULL));
1114: PetscCall(PCMGSetRhs(pc, i, *vec));
1115: PetscCall(VecDestroy(vec));
1116: PetscCall(PetscFree(vec));
1117: }
1118: if (!mglevels[i]->r && i) {
1119: PetscCall(VecDuplicate(mglevels[i]->b, &tvec));
1120: PetscCall(PCMGSetR(pc, i, tvec));
1121: PetscCall(VecDestroy(&tvec));
1122: }
1123: if (!mglevels[i]->x) {
1124: PetscCall(VecDuplicate(mglevels[i]->b, &tvec));
1125: PetscCall(PCMGSetX(pc, i, tvec));
1126: PetscCall(VecDestroy(&tvec));
1127: }
1128: if (doCR) {
1129: PetscCall(VecDuplicate(mglevels[i]->b, &mglevels[i]->crx));
1130: PetscCall(VecDuplicate(mglevels[i]->b, &mglevels[i]->crb));
1131: }
1132: }
1133: if (n != 1 && !mglevels[n - 1]->r) {
1134: /* PCMGSetR() on the finest level if user did not supply it */
1135: Vec *vec;
1137: PetscCall(KSPCreateVecs(mglevels[n - 1]->smoothd, 1, &vec, 0, NULL));
1138: PetscCall(PCMGSetR(pc, n - 1, *vec));
1139: PetscCall(VecDestroy(vec));
1140: PetscCall(PetscFree(vec));
1141: }
1142: if (doCR) {
1143: PetscCall(VecDuplicate(mglevels[n - 1]->r, &mglevels[n - 1]->crx));
1144: PetscCall(VecDuplicate(mglevels[n - 1]->r, &mglevels[n - 1]->crb));
1145: }
1146: }
1148: if (pc->dm) {
1149: /* need to tell all the coarser levels to rebuild the matrix using the DM for that level */
1150: for (PetscInt i = 0; i < n - 1; i++) {
1151: if (mglevels[i]->smoothd->setupstage != KSP_SETUP_NEW) mglevels[i]->smoothd->setupstage = KSP_SETUP_NEWMATRIX;
1152: }
1153: }
1154: // We got here (PCSetUp_MG) because the matrix has changed, which means the smoother needs to be set up again (e.g.,
1155: // new diagonal for Jacobi). Setting it here allows it to be logged under PCSetUp rather than deep inside a PCApply.
1156: if (mglevels[n - 1]->smoothd->setupstage != KSP_SETUP_NEW) mglevels[n - 1]->smoothd->setupstage = KSP_SETUP_NEWMATRIX;
1158: for (PetscInt i = 1; i < n; i++) {
1159: if (mglevels[i]->smoothu == mglevels[i]->smoothd || mg->am == PC_MG_FULL || mg->am == PC_MG_KASKADE || mg->cyclesperpcapply > 1) {
1160: /* if doing only down then initial guess is zero */
1161: PetscCall(KSPSetInitialGuessNonzero(mglevels[i]->smoothd, PETSC_TRUE));
1162: }
1163: if (mglevels[i]->cr) PetscCall(KSPSetInitialGuessNonzero(mglevels[i]->cr, PETSC_TRUE));
1164: if (mglevels[i]->eventsmoothsetup) PetscCall(PetscLogEventBegin(mglevels[i]->eventsmoothsetup, 0, 0, 0, 0));
1165: PetscCall(KSPSetUp(mglevels[i]->smoothd));
1166: if (mglevels[i]->smoothd->reason) pc->failedreason = PC_SUBPC_ERROR;
1167: if (mglevels[i]->eventsmoothsetup) PetscCall(PetscLogEventEnd(mglevels[i]->eventsmoothsetup, 0, 0, 0, 0));
1168: if (!mglevels[i]->residual) {
1169: Mat mat;
1171: PetscCall(KSPGetOperators(mglevels[i]->smoothd, &mat, NULL));
1172: PetscCall(PCMGSetResidual(pc, i, PCMGResidualDefault, mat));
1173: }
1174: if (!mglevels[i]->residualtranspose) {
1175: Mat mat;
1177: PetscCall(KSPGetOperators(mglevels[i]->smoothd, &mat, NULL));
1178: PetscCall(PCMGSetResidualTranspose(pc, i, PCMGResidualTransposeDefault, mat));
1179: }
1180: }
1181: for (PetscInt i = 1; i < n; i++) {
1182: if (mglevels[i]->smoothu && mglevels[i]->smoothu != mglevels[i]->smoothd) {
1183: Mat downmat, downpmat;
1185: /* check if operators have been set for up, if not use down operators to set them */
1186: PetscCall(KSPGetOperatorsSet(mglevels[i]->smoothu, &opsset, NULL));
1187: if (!opsset) {
1188: PetscCall(KSPGetOperators(mglevels[i]->smoothd, &downmat, &downpmat));
1189: PetscCall(KSPSetOperators(mglevels[i]->smoothu, downmat, downpmat));
1190: }
1192: PetscCall(KSPSetInitialGuessNonzero(mglevels[i]->smoothu, PETSC_TRUE));
1193: if (mglevels[i]->eventsmoothsetup) PetscCall(PetscLogEventBegin(mglevels[i]->eventsmoothsetup, 0, 0, 0, 0));
1194: PetscCall(KSPSetUp(mglevels[i]->smoothu));
1195: if (mglevels[i]->smoothu->reason) pc->failedreason = PC_SUBPC_ERROR;
1196: if (mglevels[i]->eventsmoothsetup) PetscCall(PetscLogEventEnd(mglevels[i]->eventsmoothsetup, 0, 0, 0, 0));
1197: }
1198: if (mglevels[i]->cr) {
1199: Mat downmat, downpmat;
1201: /* check if operators have been set for up, if not use down operators to set them */
1202: PetscCall(KSPGetOperatorsSet(mglevels[i]->cr, &opsset, NULL));
1203: if (!opsset) {
1204: PetscCall(KSPGetOperators(mglevels[i]->smoothd, &downmat, &downpmat));
1205: PetscCall(KSPSetOperators(mglevels[i]->cr, downmat, downpmat));
1206: }
1208: PetscCall(KSPSetInitialGuessNonzero(mglevels[i]->cr, PETSC_TRUE));
1209: if (mglevels[i]->eventsmoothsetup) PetscCall(PetscLogEventBegin(mglevels[i]->eventsmoothsetup, 0, 0, 0, 0));
1210: PetscCall(KSPSetUp(mglevels[i]->cr));
1211: if (mglevels[i]->cr->reason) pc->failedreason = PC_SUBPC_ERROR;
1212: if (mglevels[i]->eventsmoothsetup) PetscCall(PetscLogEventEnd(mglevels[i]->eventsmoothsetup, 0, 0, 0, 0));
1213: }
1214: }
1216: if (mglevels[0]->eventsmoothsetup) PetscCall(PetscLogEventBegin(mglevels[0]->eventsmoothsetup, 0, 0, 0, 0));
1217: PetscCall(KSPSetUp(mglevels[0]->smoothd));
1218: if (mglevels[0]->smoothd->reason) pc->failedreason = PC_SUBPC_ERROR;
1219: if (mglevels[0]->eventsmoothsetup) PetscCall(PetscLogEventEnd(mglevels[0]->eventsmoothsetup, 0, 0, 0, 0));
1221: /*
1222: Dump the interpolation/restriction matrices plus the
1223: Jacobian/stiffness on each level. This allows MATLAB users to
1224: easily check if the Galerkin condition A_c = R A_f R^T is satisfied.
1226: Only support one or the other at the same time.
1227: */
1228: #if defined(PETSC_USE_SOCKET_VIEWER)
1229: PetscCall(PetscOptionsGetBool(((PetscObject)pc)->options, ((PetscObject)pc)->prefix, "-pc_mg_dump_matlab", &dump, NULL));
1230: if (dump) viewer = PETSC_VIEWER_SOCKET_(PetscObjectComm((PetscObject)pc));
1231: dump = PETSC_FALSE;
1232: #endif
1233: PetscCall(PetscOptionsGetBool(((PetscObject)pc)->options, ((PetscObject)pc)->prefix, "-pc_mg_dump_binary", &dump, NULL));
1234: if (dump) viewer = PETSC_VIEWER_BINARY_(PetscObjectComm((PetscObject)pc));
1236: if (viewer) {
1237: for (PetscInt i = 1; i < n; i++) PetscCall(MatView(mglevels[i]->restrct, viewer));
1238: for (PetscInt i = 0; i < n; i++) {
1239: PetscCall(KSPGetPC(mglevels[i]->smoothd, &pc));
1240: PetscCall(MatView(pc->mat, viewer));
1241: }
1242: }
1243: PetscFunctionReturn(PETSC_SUCCESS);
1244: }
1246: PetscErrorCode PCMGGetLevels_MG(PC pc, PetscInt *levels)
1247: {
1248: PC_MG *mg = (PC_MG *)pc->data;
1250: PetscFunctionBegin;
1251: *levels = mg->nlevels;
1252: PetscFunctionReturn(PETSC_SUCCESS);
1253: }
1255: /*@
1256: PCMGGetLevels - Gets the number of levels to use with `PCMG`.
1258: Not Collective
1260: Input Parameter:
1261: . pc - the preconditioner context
1263: Output Parameter:
1264: . levels - the number of levels
1266: Level: advanced
1268: .seealso: [](ch_ksp), `PCMG`, `PCMGSetLevels()`
1269: @*/
1270: PetscErrorCode PCMGGetLevels(PC pc, PetscInt *levels)
1271: {
1272: PetscFunctionBegin;
1274: PetscAssertPointer(levels, 2);
1275: *levels = 0;
1276: PetscTryMethod(pc, "PCMGGetLevels_C", (PC, PetscInt *), (pc, levels));
1277: PetscFunctionReturn(PETSC_SUCCESS);
1278: }
1280: /*@
1281: PCMGGetGridComplexity - compute operator and grid complexity of the `PCMG` hierarchy
1283: Input Parameter:
1284: . pc - the preconditioner context
1286: Output Parameters:
1287: + gc - grid complexity = sum_i(n_i) / n_0
1288: - oc - operator complexity = sum_i(nnz_i) / nnz_0
1290: Level: advanced
1292: Note:
1293: This is often call the operator complexity in multigrid literature
1295: .seealso: [](ch_ksp), `PCMG`, `PCMGGetLevels()`, `PCMGSetLevels()`
1296: @*/
1297: PetscErrorCode PCMGGetGridComplexity(PC pc, PetscReal *gc, PetscReal *oc)
1298: {
1299: PC_MG *mg = (PC_MG *)pc->data;
1300: PC_MG_Levels **mglevels = mg->levels;
1301: PetscInt N;
1302: PetscLogDouble nnz0 = 0, sgc = 0, soc = 0, n0 = 0;
1303: MatInfo info;
1305: PetscFunctionBegin;
1307: if (gc) PetscAssertPointer(gc, 2);
1308: if (oc) PetscAssertPointer(oc, 3);
1309: if (!pc->setupcalled) {
1310: if (gc) *gc = 0;
1311: if (oc) *oc = 0;
1312: PetscFunctionReturn(PETSC_SUCCESS);
1313: }
1314: PetscCheck(mg->nlevels > 0, PETSC_COMM_SELF, PETSC_ERR_PLIB, "MG has no levels");
1315: for (PetscInt lev = 0; lev < mg->nlevels; lev++) {
1316: Mat dB;
1317: PetscCall(KSPGetOperators(mglevels[lev]->smoothd, NULL, &dB));
1318: PetscCall(MatGetInfo(dB, MAT_GLOBAL_SUM, &info)); /* global reduction */
1319: PetscCall(MatGetSize(dB, &N, NULL));
1320: sgc += N;
1321: soc += info.nz_used;
1322: if (lev == mg->nlevels - 1) {
1323: nnz0 = info.nz_used;
1324: n0 = N;
1325: }
1326: }
1327: PetscCheck(n0 > 0 && gc, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Number for grid points on finest level is not available");
1328: *gc = (PetscReal)(sgc / n0);
1329: if (nnz0 > 0 && oc) *oc = (PetscReal)(soc / nnz0);
1330: PetscFunctionReturn(PETSC_SUCCESS);
1331: }
1333: /*@
1334: PCMGSetType - Determines the form of multigrid to use, either
1335: multiplicative, additive, full, or the Kaskade algorithm.
1337: Logically Collective
1339: Input Parameters:
1340: + pc - the preconditioner context
1341: - form - multigrid form, one of `PC_MG_MULTIPLICATIVE`, `PC_MG_ADDITIVE`, `PC_MG_FULL`, `PC_MG_KASKADE`
1343: Options Database Key:
1344: . -pc_mg_type form - Sets form, one of multiplicative, additive, full, kaskade
1346: Level: advanced
1348: .seealso: [](ch_ksp), `PCMGType`, `PCMG`, `PCMGGetLevels()`, `PCMGSetLevels()`, `PCMGGetType()`, `PCMGCycleType`
1349: @*/
1350: PetscErrorCode PCMGSetType(PC pc, PCMGType form)
1351: {
1352: PC_MG *mg = (PC_MG *)pc->data;
1354: PetscFunctionBegin;
1357: mg->am = form;
1358: if (form == PC_MG_MULTIPLICATIVE) pc->ops->applyrichardson = PCApplyRichardson_MG;
1359: else pc->ops->applyrichardson = NULL;
1360: PetscFunctionReturn(PETSC_SUCCESS);
1361: }
1363: /*@
1364: PCMGGetType - Finds the form of multigrid the `PCMG` is using multiplicative, additive, full, or the Kaskade algorithm.
1366: Logically Collective
1368: Input Parameter:
1369: . pc - the preconditioner context
1371: Output Parameter:
1372: . type - one of `PC_MG_MULTIPLICATIVE`, `PC_MG_ADDITIVE`, `PC_MG_FULL`, `PC_MG_KASKADE`, `PCMGCycleType`
1374: Level: advanced
1376: .seealso: [](ch_ksp), `PCMGType`, `PCMG`, `PCMGGetLevels()`, `PCMGSetLevels()`, `PCMGSetType()`
1377: @*/
1378: PetscErrorCode PCMGGetType(PC pc, PCMGType *type)
1379: {
1380: PC_MG *mg = (PC_MG *)pc->data;
1382: PetscFunctionBegin;
1384: *type = mg->am;
1385: PetscFunctionReturn(PETSC_SUCCESS);
1386: }
1388: /*@
1389: PCMGSetCycleType - Sets the type cycles to use. Use `PCMGSetCycleTypeOnLevel()` for more
1390: complicated cycling.
1392: Logically Collective
1394: Input Parameters:
1395: + pc - the multigrid context
1396: - n - either `PC_MG_CYCLE_V` or `PC_MG_CYCLE_W`
1398: Options Database Key:
1399: . -pc_mg_cycle_type (v|w) - provide the cycle desired
1401: Level: advanced
1403: .seealso: [](ch_ksp), `PCMG`, `PCMGSetCycleTypeOnLevel()`, `PCMGType`, `PCMGCycleType`
1404: @*/
1405: PetscErrorCode PCMGSetCycleType(PC pc, PCMGCycleType n)
1406: {
1407: PC_MG *mg = (PC_MG *)pc->data;
1408: PC_MG_Levels **mglevels = mg->levels;
1409: PetscInt i, levels;
1411: PetscFunctionBegin;
1414: PetscCheck(mglevels, PetscObjectComm((PetscObject)pc), PETSC_ERR_ORDER, "Must set MG levels with PCMGSetLevels() before calling");
1415: levels = mglevels[0]->levels;
1416: for (i = 0; i < levels; i++) mglevels[i]->cycles = n;
1417: PetscFunctionReturn(PETSC_SUCCESS);
1418: }
1420: /*@
1421: PCMGMultiplicativeSetCycles - Sets the number of cycles to use for each preconditioner step
1422: of multigrid when `PCMGType` is `PC_MG_MULTIPLICATIVE`
1424: Logically Collective
1426: Input Parameters:
1427: + pc - the multigrid context
1428: - n - number of cycles (default is 1)
1430: Options Database Key:
1431: . -pc_mg_multiplicative_cycles n - set the number of cycles
1433: Level: advanced
1435: Note:
1436: This is not associated with setting a v or w cycle, that is set with `PCMGSetCycleType()`
1438: .seealso: [](ch_ksp), `PCMGSetCycleTypeOnLevel()`, `PCMGSetCycleType()`, `PCMGCycleType`, `PCMGType`
1439: @*/
1440: PetscErrorCode PCMGMultiplicativeSetCycles(PC pc, PetscInt n)
1441: {
1442: PC_MG *mg = (PC_MG *)pc->data;
1444: PetscFunctionBegin;
1447: mg->cyclesperpcapply = n;
1448: PetscFunctionReturn(PETSC_SUCCESS);
1449: }
1451: /*
1452: Since the finest level KSP shares the original matrix (of the entire system), it's preconditioner
1453: should not be updated if the whole PC is supposed to reuse the preconditioner
1454: */
1455: static PetscErrorCode PCSetReusePreconditioner_MG(PC pc, PetscBool flag)
1456: {
1457: PC_MG *mg = (PC_MG *)pc->data;
1458: PC_MG_Levels **mglevels = mg->levels;
1459: PetscInt levels;
1460: PC tpc;
1462: PetscFunctionBegin;
1465: if (mglevels) {
1466: levels = mglevels[0]->levels;
1467: PetscCall(KSPGetPC(mglevels[levels - 1]->smoothd, &tpc));
1468: tpc->reusepreconditioner = flag;
1469: PetscCall(KSPGetPC(mglevels[levels - 1]->smoothu, &tpc));
1470: tpc->reusepreconditioner = flag;
1471: }
1472: PetscFunctionReturn(PETSC_SUCCESS);
1473: }
1475: static PetscErrorCode PCMGSetGalerkin_MG(PC pc, PCMGGalerkinType use)
1476: {
1477: PC_MG *mg = (PC_MG *)pc->data;
1479: PetscFunctionBegin;
1480: mg->galerkin = use;
1481: PetscFunctionReturn(PETSC_SUCCESS);
1482: }
1484: /*@
1485: PCMGSetGalerkin - Causes the coarser grid matrices to be computed from the
1486: finest grid via the Galerkin process: A_i-1 = r_i * A_i * p_i
1488: Logically Collective
1490: Input Parameters:
1491: + pc - the multigrid context
1492: - use - one of `PC_MG_GALERKIN_BOTH`, `PC_MG_GALERKIN_PMAT`, `PC_MG_GALERKIN_MAT`, or `PC_MG_GALERKIN_NONE`
1494: Options Database Key:
1495: . -pc_mg_galerkin (both|pmat|mat|none) - set the matrices to form via the Galerkin process
1497: Level: intermediate
1499: Note:
1500: Some codes that use `PCMG` such as `PCGAMG` use Galerkin internally while constructing the hierarchy and thus do not
1501: use the `PCMG` construction of the coarser grids.
1503: .seealso: [](ch_ksp), `PCMG`, `PCMGGetGalerkin()`, `PCMGGalerkinType`
1504: @*/
1505: PetscErrorCode PCMGSetGalerkin(PC pc, PCMGGalerkinType use)
1506: {
1507: PetscFunctionBegin;
1509: PetscTryMethod(pc, "PCMGSetGalerkin_C", (PC, PCMGGalerkinType), (pc, use));
1510: PetscFunctionReturn(PETSC_SUCCESS);
1511: }
1513: /*@
1514: PCMGGetGalerkin - Checks if Galerkin multigrid is being used, i.e. A_i-1 = r_i * A_i * p_i
1516: Not Collective
1518: Input Parameter:
1519: . pc - the multigrid context
1521: Output Parameter:
1522: . galerkin - one of `PC_MG_GALERKIN_BOTH`,`PC_MG_GALERKIN_PMAT`,`PC_MG_GALERKIN_MAT`, `PC_MG_GALERKIN_NONE`, or `PC_MG_GALERKIN_EXTERNAL`
1524: Level: intermediate
1526: .seealso: [](ch_ksp), `PCMG`, `PCMGSetGalerkin()`, `PCMGGalerkinType`
1527: @*/
1528: PetscErrorCode PCMGGetGalerkin(PC pc, PCMGGalerkinType *galerkin)
1529: {
1530: PC_MG *mg = (PC_MG *)pc->data;
1532: PetscFunctionBegin;
1534: *galerkin = mg->galerkin;
1535: PetscFunctionReturn(PETSC_SUCCESS);
1536: }
1538: static PetscErrorCode PCMGSetAdaptInterpolation_MG(PC pc, PetscBool adapt)
1539: {
1540: PC_MG *mg = (PC_MG *)pc->data;
1542: PetscFunctionBegin;
1543: mg->adaptInterpolation = adapt;
1544: PetscFunctionReturn(PETSC_SUCCESS);
1545: }
1547: static PetscErrorCode PCMGGetAdaptInterpolation_MG(PC pc, PetscBool *adapt)
1548: {
1549: PC_MG *mg = (PC_MG *)pc->data;
1551: PetscFunctionBegin;
1552: *adapt = mg->adaptInterpolation;
1553: PetscFunctionReturn(PETSC_SUCCESS);
1554: }
1556: static PetscErrorCode PCMGSetAdaptCoarseSpaceType_MG(PC pc, PCMGCoarseSpaceType ctype)
1557: {
1558: PC_MG *mg = (PC_MG *)pc->data;
1560: PetscFunctionBegin;
1561: mg->adaptInterpolation = ctype != PCMG_ADAPT_NONE ? PETSC_TRUE : PETSC_FALSE;
1562: mg->coarseSpaceType = ctype;
1563: PetscCall(PCMGSetGalerkin(pc, PC_MG_GALERKIN_BOTH));
1564: PetscFunctionReturn(PETSC_SUCCESS);
1565: }
1567: static PetscErrorCode PCMGGetAdaptCoarseSpaceType_MG(PC pc, PCMGCoarseSpaceType *ctype)
1568: {
1569: PC_MG *mg = (PC_MG *)pc->data;
1571: PetscFunctionBegin;
1572: *ctype = mg->coarseSpaceType;
1573: PetscFunctionReturn(PETSC_SUCCESS);
1574: }
1576: static PetscErrorCode PCMGSetAdaptCR_MG(PC pc, PetscBool cr)
1577: {
1578: PC_MG *mg = (PC_MG *)pc->data;
1580: PetscFunctionBegin;
1581: mg->compatibleRelaxation = cr;
1582: PetscFunctionReturn(PETSC_SUCCESS);
1583: }
1585: static PetscErrorCode PCMGGetAdaptCR_MG(PC pc, PetscBool *cr)
1586: {
1587: PC_MG *mg = (PC_MG *)pc->data;
1589: PetscFunctionBegin;
1590: *cr = mg->compatibleRelaxation;
1591: PetscFunctionReturn(PETSC_SUCCESS);
1592: }
1594: /*@
1595: PCMGSetAdaptCoarseSpaceType - Set the type of adaptive coarse space.
1597: Adapts or creates the interpolator based upon a vector space which should be accurately captured by the next coarser mesh, and thus accurately interpolated.
1599: Logically Collective
1601: Input Parameters:
1602: + pc - the multigrid context
1603: - ctype - the type of coarse space
1605: Options Database Keys:
1606: + -pc_mg_adapt_interp_n nmodes - The number of modes to use
1607: - -pc_mg_adapt_interp_coarse_space type - The type of coarse space: none, `polynomial`, `harmonic`, `eigenvector`, `generalized_eigenvector`, `gdsw`
1609: Level: intermediate
1611: Note:
1612: Requires a `DM` with specific functionality be attached to the `PC`.
1614: .seealso: [](ch_ksp), `PCMG`, `PCMGCoarseSpaceType`, `PCMGGetAdaptCoarseSpaceType()`, `PCMGSetGalerkin()`, `PCMGSetAdaptInterpolation()`, `DM`
1615: @*/
1616: PetscErrorCode PCMGSetAdaptCoarseSpaceType(PC pc, PCMGCoarseSpaceType ctype)
1617: {
1618: PetscFunctionBegin;
1621: PetscTryMethod(pc, "PCMGSetAdaptCoarseSpaceType_C", (PC, PCMGCoarseSpaceType), (pc, ctype));
1622: PetscFunctionReturn(PETSC_SUCCESS);
1623: }
1625: /*@
1626: PCMGGetAdaptCoarseSpaceType - Get the type of adaptive coarse space.
1628: Not Collective
1630: Input Parameter:
1631: . pc - the multigrid context
1633: Output Parameter:
1634: . ctype - the type of coarse space
1636: Level: intermediate
1638: .seealso: [](ch_ksp), `PCMG`, `PCMGCoarseSpaceType`, `PCMGSetAdaptCoarseSpaceType()`, `PCMGSetGalerkin()`, `PCMGSetAdaptInterpolation()`
1639: @*/
1640: PetscErrorCode PCMGGetAdaptCoarseSpaceType(PC pc, PCMGCoarseSpaceType *ctype)
1641: {
1642: PetscFunctionBegin;
1644: PetscAssertPointer(ctype, 2);
1645: PetscUseMethod(pc, "PCMGGetAdaptCoarseSpaceType_C", (PC, PCMGCoarseSpaceType *), (pc, ctype));
1646: PetscFunctionReturn(PETSC_SUCCESS);
1647: }
1649: /* MATT: REMOVE? */
1650: /*@
1651: PCMGSetAdaptInterpolation - Adapt the interpolator based upon a vector space which should be accurately captured by the next coarser mesh, and thus accurately interpolated.
1653: Logically Collective
1655: Input Parameters:
1656: + pc - the multigrid context
1657: - adapt - flag for adaptation of the interpolator
1659: Options Database Keys:
1660: + -pc_mg_adapt_interp - Turn on adaptation
1661: . -pc_mg_adapt_interp_n nmodes - The number of modes to use, should be divisible by dimension
1662: - -pc_mg_adapt_interp_coarse_space type - The type of coarse space: polynomial, harmonic, eigenvector, generalized_eigenvector
1664: Level: intermediate
1666: .seealso: [](ch_ksp), `PCMG`, `PCMGGetAdaptInterpolation()`, `PCMGSetGalerkin()`, `PCMGGetAdaptCoarseSpaceType()`, `PCMGSetAdaptCoarseSpaceType()`
1667: @*/
1668: PetscErrorCode PCMGSetAdaptInterpolation(PC pc, PetscBool adapt)
1669: {
1670: PetscFunctionBegin;
1672: PetscTryMethod(pc, "PCMGSetAdaptInterpolation_C", (PC, PetscBool), (pc, adapt));
1673: PetscFunctionReturn(PETSC_SUCCESS);
1674: }
1676: /*@
1677: PCMGGetAdaptInterpolation - Get the flag to adapt the interpolator based upon a vector space which should be accurately captured by the next coarser mesh,
1678: and thus accurately interpolated.
1680: Not Collective
1682: Input Parameter:
1683: . pc - the multigrid context
1685: Output Parameter:
1686: . adapt - flag for adaptation of the interpolator
1688: Level: intermediate
1690: .seealso: [](ch_ksp), `PCMG`, `PCMGSetAdaptInterpolation()`, `PCMGSetGalerkin()`, `PCMGGetAdaptCoarseSpaceType()`, `PCMGSetAdaptCoarseSpaceType()`
1691: @*/
1692: PetscErrorCode PCMGGetAdaptInterpolation(PC pc, PetscBool *adapt)
1693: {
1694: PetscFunctionBegin;
1696: PetscAssertPointer(adapt, 2);
1697: PetscUseMethod(pc, "PCMGGetAdaptInterpolation_C", (PC, PetscBool *), (pc, adapt));
1698: PetscFunctionReturn(PETSC_SUCCESS);
1699: }
1701: /*@
1702: PCMGSetAdaptCR - Monitor the coarse space quality using an auxiliary solve with compatible relaxation.
1704: Logically Collective
1706: Input Parameters:
1707: + pc - the multigrid context
1708: - cr - flag for compatible relaxation
1710: Options Database Key:
1711: . -pc_mg_adapt_cr - Turn on compatible relaxation
1713: Level: intermediate
1715: .seealso: [](ch_ksp), `PCMG`, `PCMGGetAdaptCR()`, `PCMGSetAdaptInterpolation()`, `PCMGSetGalerkin()`, `PCMGGetAdaptCoarseSpaceType()`, `PCMGSetAdaptCoarseSpaceType()`
1716: @*/
1717: PetscErrorCode PCMGSetAdaptCR(PC pc, PetscBool cr)
1718: {
1719: PetscFunctionBegin;
1721: PetscTryMethod(pc, "PCMGSetAdaptCR_C", (PC, PetscBool), (pc, cr));
1722: PetscFunctionReturn(PETSC_SUCCESS);
1723: }
1725: /*@
1726: PCMGGetAdaptCR - Get the flag to monitor coarse space quality using an auxiliary solve with compatible relaxation.
1728: Not Collective
1730: Input Parameter:
1731: . pc - the multigrid context
1733: Output Parameter:
1734: . cr - flag for compatible relaxaion
1736: Level: intermediate
1738: .seealso: [](ch_ksp), `PCMGSetAdaptCR()`, `PCMGGetAdaptInterpolation()`, `PCMGSetGalerkin()`, `PCMGGetAdaptCoarseSpaceType()`, `PCMGSetAdaptCoarseSpaceType()`
1739: @*/
1740: PetscErrorCode PCMGGetAdaptCR(PC pc, PetscBool *cr)
1741: {
1742: PetscFunctionBegin;
1744: PetscAssertPointer(cr, 2);
1745: PetscUseMethod(pc, "PCMGGetAdaptCR_C", (PC, PetscBool *), (pc, cr));
1746: PetscFunctionReturn(PETSC_SUCCESS);
1747: }
1749: /*@
1750: PCMGSetNumberSmooth - Sets the number of pre and post-smoothing steps to use
1751: on all levels. Use `PCMGDistinctSmoothUp()` to create separate up and down smoothers if you want different numbers of
1752: pre- and post-smoothing steps.
1754: Logically Collective
1756: Input Parameters:
1757: + pc - the multigrid context
1758: - n - the number of smoothing steps
1760: Options Database Key:
1761: . -mg_levels_ksp_max_it n - Sets number of pre and post-smoothing steps
1763: Level: advanced
1765: Note:
1766: This does not set a value on the coarsest grid, since we assume that there is no separate smooth up on the coarsest grid.
1768: .seealso: [](ch_ksp), `PCMG`, `PCMGSetDistinctSmoothUp()`
1769: @*/
1770: PetscErrorCode PCMGSetNumberSmooth(PC pc, PetscInt n)
1771: {
1772: PC_MG *mg = (PC_MG *)pc->data;
1773: PC_MG_Levels **mglevels = mg->levels;
1774: PetscInt levels;
1776: PetscFunctionBegin;
1779: PetscCheck(mglevels, PetscObjectComm((PetscObject)pc), PETSC_ERR_ORDER, "Must set MG levels with PCMGSetLevels() before calling");
1780: levels = mglevels[0]->levels;
1782: for (PetscInt i = 1; i < levels; i++) {
1783: PetscCall(KSPSetTolerances(mglevels[i]->smoothu, PETSC_CURRENT, PETSC_CURRENT, PETSC_CURRENT, n));
1784: PetscCall(KSPSetTolerances(mglevels[i]->smoothd, PETSC_CURRENT, PETSC_CURRENT, PETSC_CURRENT, n));
1785: mg->default_smoothu = n;
1786: mg->default_smoothd = n;
1787: }
1788: PetscFunctionReturn(PETSC_SUCCESS);
1789: }
1791: /*@
1792: PCMGSetDistinctSmoothUp - sets the up (post) smoother to be a separate `KSP` from the down (pre) smoother on all levels
1793: and adds the suffix _up to the options name
1795: Logically Collective
1797: Input Parameter:
1798: . pc - the preconditioner context
1800: Options Database Key:
1801: . -pc_mg_distinct_smoothup (true|false) - use distinct smoothing objects
1803: Level: advanced
1805: Note:
1806: This does not set a value on the coarsest grid, since we assume that there is no separate smooth up on the coarsest grid.
1808: .seealso: [](ch_ksp), `PCMG`, `PCMGSetNumberSmooth()`
1809: @*/
1810: PetscErrorCode PCMGSetDistinctSmoothUp(PC pc)
1811: {
1812: PC_MG *mg = (PC_MG *)pc->data;
1813: PC_MG_Levels **mglevels = mg->levels;
1814: PetscInt levels;
1815: KSP subksp;
1817: PetscFunctionBegin;
1819: PetscCheck(mglevels, PetscObjectComm((PetscObject)pc), PETSC_ERR_ORDER, "Must set MG levels with PCMGSetLevels() before calling");
1820: levels = mglevels[0]->levels;
1822: for (PetscInt i = 1; i < levels; i++) {
1823: const char *prefix = NULL;
1824: /* make sure smoother up and down are different */
1825: PetscCall(PCMGGetSmootherUp(pc, i, &subksp));
1826: PetscCall(KSPGetOptionsPrefix(mglevels[i]->smoothd, &prefix));
1827: PetscCall(KSPSetOptionsPrefix(subksp, prefix));
1828: PetscCall(KSPAppendOptionsPrefix(subksp, "up_"));
1829: }
1830: PetscFunctionReturn(PETSC_SUCCESS);
1831: }
1833: /* No new matrices are created, and the coarse operator matrices are the references to the original ones */
1834: static PetscErrorCode PCGetInterpolations_MG(PC pc, PetscInt *num_levels, Mat *interpolations[])
1835: {
1836: PC_MG *mg = (PC_MG *)pc->data;
1837: PC_MG_Levels **mglevels = mg->levels;
1838: Mat *mat;
1840: PetscFunctionBegin;
1841: PetscCheck(mglevels, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONGSTATE, "Must set MG levels before calling");
1842: PetscCall(PetscMalloc1(mg->nlevels, &mat));
1843: for (PetscInt l = 1; l < mg->nlevels; l++) {
1844: mat[l - 1] = mglevels[l]->interpolate;
1845: PetscCall(PetscObjectReference((PetscObject)mat[l - 1]));
1846: }
1847: *num_levels = mg->nlevels;
1848: *interpolations = mat;
1849: PetscFunctionReturn(PETSC_SUCCESS);
1850: }
1852: /* No new matrices are created, and the coarse operator matrices are the references to the original ones */
1853: static PetscErrorCode PCGetCoarseOperators_MG(PC pc, PetscInt *num_levels, Mat *coarseOperators[])
1854: {
1855: PC_MG *mg = (PC_MG *)pc->data;
1856: PC_MG_Levels **mglevels = mg->levels;
1857: Mat *mat;
1859: PetscFunctionBegin;
1860: PetscCheck(mglevels, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONGSTATE, "Must set MG levels before calling");
1861: PetscCall(PetscMalloc1(mg->nlevels, &mat));
1862: for (PetscInt l = 0; l < mg->nlevels - 1; l++) {
1863: PetscCall(KSPGetOperators(mglevels[l]->smoothd, NULL, &mat[l]));
1864: PetscCall(PetscObjectReference((PetscObject)mat[l]));
1865: }
1866: *num_levels = mg->nlevels;
1867: *coarseOperators = mat;
1868: PetscFunctionReturn(PETSC_SUCCESS);
1869: }
1871: /*@C
1872: PCMGRegisterCoarseSpaceConstructor - Adds a method to the `PCMG` package for coarse space construction.
1874: Not Collective, No Fortran Support
1876: Input Parameters:
1877: + name - name of the constructor
1878: - function - constructor routine, see `PCMGCoarseSpaceConstructorFn`
1880: Level: advanced
1882: Developer Notes:
1883: This does not appear to be used anywhere
1885: .seealso: [](ch_ksp), `PCMGCoarseSpaceConstructorFn`, `PCMG`, `PCMGGetCoarseSpaceConstructor()`, `PCRegister()`
1886: @*/
1887: PetscErrorCode PCMGRegisterCoarseSpaceConstructor(const char name[], PCMGCoarseSpaceConstructorFn *function)
1888: {
1889: PetscFunctionBegin;
1890: PetscCall(PCInitializePackage());
1891: PetscCall(PetscFunctionListAdd(&PCMGCoarseList, name, function));
1892: PetscFunctionReturn(PETSC_SUCCESS);
1893: }
1895: /*@C
1896: PCMGGetCoarseSpaceConstructor - Returns the given coarse space construction method.
1898: Not Collective, No Fortran Support
1900: Input Parameter:
1901: . name - name of the constructor
1903: Output Parameter:
1904: . function - constructor routine
1906: Level: advanced
1908: .seealso: [](ch_ksp), `PCMGCoarseSpaceConstructorFn`, `PCMG`, `PCMGRegisterCoarseSpaceConstructor()`, `PCRegister()`
1909: @*/
1910: PetscErrorCode PCMGGetCoarseSpaceConstructor(const char name[], PCMGCoarseSpaceConstructorFn **function)
1911: {
1912: PetscFunctionBegin;
1913: PetscCall(PetscFunctionListFind(PCMGCoarseList, name, function));
1914: PetscFunctionReturn(PETSC_SUCCESS);
1915: }
1917: /*MC
1918: PCMG - Use multigrid preconditioning. This preconditioner requires you provide additional information about the restriction/interpolation
1919: operators using `PCMGSetInterpolation()` and/or `PCMGSetRestriction()`(and possibly the coarser grid matrices) or a `DM` that can provide such information.
1921: Options Database Keys:
1922: + -pc_mg_levels nlevels - number of levels including finest
1923: . -pc_mg_cycle_type (v|w) - provide the cycle desired
1924: . -pc_mg_type (additive|multiplicative|full|kaskade) - multiplicative is the default
1925: . -pc_mg_log - log information about time spent on each level of the solver
1926: . -pc_mg_distinct_smoothup - configure up (after interpolation) and down (before restriction) smoothers separately (with different options prefixes)
1927: . -pc_mg_galerkin (both|pmat|mat|none) - use the Galerkin process to compute coarser operators, i.e., $A_{coarse} = R A_{fine} R^T$
1928: . -pc_mg_multiplicative_cycles ncycles - number of cycles to use as the preconditioner (defaults to 1)
1929: . -pc_mg_dump_matlab - dumps the matrices for each level and the restriction/interpolation matrices
1930: to a `PETSCVIEWERSOCKET` for reading from MATLAB.
1931: - -pc_mg_dump_binary - dumps the matrices for each level and the restriction/interpolation matrices
1932: to the binary output file called binaryoutput
1934: Level: intermediate
1936: Notes:
1937: `PCMG` provides a general framework for implementing multigrid methods. Use `PCGAMG` for PETSc's algebraic multigrid preconditioner, `PCHYPRE` for hypre's
1938: BoomerAMG algebraic multigrid, and `PCML` for Trilinos's ML preconditioner. `PCAMGX` provides access to NVIDIA's AmgX algebraic multigrid.
1940: If you use `KSPSetDM()` (or `SNESSetDM()` or `TSSetDM()`) with an appropriate `DM`, such as `DMDA`, then `PCMG` will use the geometric information
1941: from the `DM` to generate appropriate restriction and interpolation information and construct a geometric multigrid.
1943: If you do not provide an appropriate `DM` and do not provide restriction or interpolation operators with `PCMGSetInterpolation()` and/or `PCMGSetRestriction()`,
1944: then `PCMG` will run multigrid with only a single level (so not really multigrid).
1946: The Krylov solver (if any) and preconditioner (smoother) and their parameters are controlled from the options database with the standard
1947: options database keywords prefixed with `-mg_levels_` to affect all the levels but the coarsest, which is controlled with `-mg_coarse_`,
1948: and the finest where `-mg_fine_` can override `-mg_levels_`. One can set different preconditioners etc on specific levels with the prefix
1949: `-mg_levels_n_` where `n` is the level number (zero being the coarse level. For example
1950: .vb
1951: -mg_levels_ksp_type gmres -mg_levels_pc_type bjacobi -mg_coarse_pc_type svd -mg_levels_2_pc_type sor
1952: .ve
1953: These options also work for controlling the smoothers etc inside `PCGAMG`
1955: If one uses a Krylov method such `KSPGMRES` or `KSPCG` as the smoother than one must use `KSPFGMRES`, `KSPGCR`, or `KSPRICHARDSON` as the outer Krylov method
1957: When run with a single level the smoother options are used on that level NOT the coarse grid solver options
1959: When run with `KSPRICHARDSON` the convergence test changes slightly if monitor is turned on. The iteration count may change slightly. This
1960: is because without monitoring the residual norm is computed WITHIN each multigrid cycle on the finest level after the pre-smoothing
1961: (because the residual has just been computed for the multigrid algorithm and is hence available for free) while with monitoring the
1962: residual is computed at the end of each cycle.
1964: .seealso: [](sec_mg), `PCCreate()`, `PCSetType()`, `PCType`, `PC`, `PCMGType`, `PCEXOTIC`, `PCGAMG`, `PCML`, `PCHYPRE`,
1965: `PCMGSetLevels()`, `PCMGGetLevels()`, `PCMGSetType()`, `PCMGSetCycleType()`,
1966: `PCMGSetDistinctSmoothUp()`, `PCMGGetCoarseSolve()`, `PCMGSetResidual()`, `PCMGSetInterpolation()`,
1967: `PCMGSetRestriction()`, `PCMGGetSmoother()`, `PCMGGetSmootherUp()`, `PCMGGetSmootherDown()`,
1968: `PCMGSetCycleTypeOnLevel()`, `PCMGSetRhs()`, `PCMGSetX()`, `PCMGSetR()`,
1969: `PCMGSetAdaptCR()`, `PCMGGetAdaptInterpolation()`, `PCMGSetGalerkin()`, `PCMGGetAdaptCoarseSpaceType()`, `PCMGSetAdaptCoarseSpaceType()`
1970: M*/
1972: PETSC_EXTERN PetscErrorCode PCCreate_MG(PC pc)
1973: {
1974: PC_MG *mg;
1976: PetscFunctionBegin;
1977: PetscCall(PetscNew(&mg));
1978: pc->data = mg;
1979: mg->nlevels = -1;
1980: mg->am = PC_MG_MULTIPLICATIVE;
1981: mg->galerkin = PC_MG_GALERKIN_NONE;
1982: mg->adaptInterpolation = PETSC_FALSE;
1983: mg->Nc = -1;
1984: mg->eigenvalue = -1;
1986: pc->useAmat = PETSC_TRUE;
1988: pc->ops->apply = PCApply_MG;
1989: pc->ops->applytranspose = PCApplyTranspose_MG;
1990: pc->ops->matapply = PCMatApply_MG;
1991: pc->ops->matapplytranspose = PCMatApplyTranspose_MG;
1992: pc->ops->setup = PCSetUp_MG;
1993: pc->ops->reset = PCReset_MG;
1994: pc->ops->destroy = PCDestroy_MG;
1995: pc->ops->setfromoptions = PCSetFromOptions_MG;
1996: pc->ops->view = PCView_MG;
1998: PetscCall(PetscObjectComposedDataRegister(&mg->eigenvalue));
1999: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGSetGalerkin_C", PCMGSetGalerkin_MG));
2000: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCSetReusePreconditioner_C", PCSetReusePreconditioner_MG));
2001: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGGetLevels_C", PCMGGetLevels_MG));
2002: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGSetLevels_C", PCMGSetLevels_MG));
2003: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCGetInterpolations_C", PCGetInterpolations_MG));
2004: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCGetCoarseOperators_C", PCGetCoarseOperators_MG));
2005: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGSetAdaptInterpolation_C", PCMGSetAdaptInterpolation_MG));
2006: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGGetAdaptInterpolation_C", PCMGGetAdaptInterpolation_MG));
2007: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGSetAdaptCR_C", PCMGSetAdaptCR_MG));
2008: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGGetAdaptCR_C", PCMGGetAdaptCR_MG));
2009: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGSetAdaptCoarseSpaceType_C", PCMGSetAdaptCoarseSpaceType_MG));
2010: PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCMGGetAdaptCoarseSpaceType_C", PCMGGetAdaptCoarseSpaceType_MG));
2011: PetscFunctionReturn(PETSC_SUCCESS);
2012: }