Actual source code: snesngmres.c
1: #include <../src/snes/impls/ngmres/snesngmres.h>
2: #include <petscblaslapack.h>
3: #include <petscdm.h>
5: const char *const SNESNGMRESRestartTypes[] = {"NONE", "PERIODIC", "DIFFERENCE", "SNESNGMRESRestartType", "SNES_NGMRES_RESTART_", NULL};
6: const char *const SNESNGMRESSelectTypes[] = {"NONE", "DIFFERENCE", "LINESEARCH", "SNESNGMRESSelectType", "SNES_NGMRES_SELECT_", NULL};
8: PetscErrorCode SNESReset_NGMRES(SNES snes)
9: {
10: SNES_NGMRES *ngmres = (SNES_NGMRES *)snes->data;
12: PetscFunctionBegin;
13: PetscCall(VecDestroyVecs(ngmres->msize, &ngmres->Fdot));
14: PetscCall(VecDestroyVecs(ngmres->msize, &ngmres->Xdot));
15: PetscCall(SNESLineSearchDestroy(&ngmres->additive_linesearch));
16: PetscFunctionReturn(PETSC_SUCCESS);
17: }
19: PetscErrorCode SNESDestroy_NGMRES(SNES snes)
20: {
21: SNES_NGMRES *ngmres = (SNES_NGMRES *)snes->data;
23: PetscFunctionBegin;
24: PetscCall(SNESReset_NGMRES(snes));
25: PetscCall(PetscFree4(ngmres->h, ngmres->beta, ngmres->xi, ngmres->q));
26: PetscCall(PetscFree3(ngmres->xnorms, ngmres->fnorms, ngmres->s));
27: #if defined(PETSC_USE_COMPLEX)
28: PetscCall(PetscFree(ngmres->rwork));
29: #endif
30: PetscCall(PetscFree(ngmres->work));
31: PetscCall(PetscObjectComposeFunction((PetscObject)snes, "SNESNGMRESSetSelectType_C", NULL));
32: PetscCall(PetscObjectComposeFunction((PetscObject)snes, "SNESNGMRESSetRestartType_C", NULL));
33: PetscCall(PetscObjectComposeFunction((PetscObject)snes, "SNESNGMRESSetRestartFmRise_C", NULL));
34: PetscCall(PetscObjectComposeFunction((PetscObject)snes, "SNESNGMRESGetRestartFmRise_C", NULL));
35: PetscCall(PetscFree(snes->data));
36: PetscFunctionReturn(PETSC_SUCCESS);
37: }
39: PetscErrorCode SNESSetUp_NGMRES(SNES snes)
40: {
41: SNES_NGMRES *ngmres = (SNES_NGMRES *)snes->data;
42: PetscInt msize, hsize;
43: DM dm;
45: PetscFunctionBegin;
46: PetscCheck(!snes->npc || snes->npcside != PC_LEFT || snes->functype != SNES_FUNCTION_UNPRECONDITIONED, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_WRONGSTATE, "SNESNGMRES does not support left preconditioning with unpreconditioned function");
47: if (snes->npcside == PC_LEFT && snes->functype == SNES_FUNCTION_DEFAULT) snes->functype = SNES_FUNCTION_PRECONDITIONED;
48: PetscCall(SNESSetWorkVecs(snes, 5));
50: if (!snes->vec_sol) {
51: PetscCall(SNESGetDM(snes, &dm));
52: PetscCall(DMCreateGlobalVector(dm, &snes->vec_sol));
53: }
55: if (!ngmres->Xdot) PetscCall(VecDuplicateVecs(snes->vec_sol, ngmres->msize, &ngmres->Xdot));
56: if (!ngmres->Fdot) PetscCall(VecDuplicateVecs(snes->vec_sol, ngmres->msize, &ngmres->Fdot));
57: if (!ngmres->setup_called) {
58: msize = ngmres->msize; /* restart size */
59: hsize = msize * msize;
61: /* explicit least squares minimization solve */
62: PetscCall(PetscCalloc4(hsize, &ngmres->h, msize, &ngmres->beta, msize, &ngmres->xi, hsize, &ngmres->q));
63: PetscCall(PetscMalloc3(msize, &ngmres->xnorms, msize, &ngmres->fnorms, msize, &ngmres->s));
64: ngmres->nrhs = 1;
65: PetscCall(PetscBLASIntCast(msize, &ngmres->lda));
66: PetscCall(PetscBLASIntCast(msize, &ngmres->ldb));
67: PetscCall(PetscBLASIntCast(12 * msize, &ngmres->lwork));
68: #if defined(PETSC_USE_COMPLEX)
69: PetscCall(PetscMalloc1(ngmres->lwork, &ngmres->rwork));
70: #endif
71: PetscCall(PetscMalloc1(ngmres->lwork, &ngmres->work));
72: }
74: ngmres->setup_called = PETSC_TRUE;
75: PetscFunctionReturn(PETSC_SUCCESS);
76: }
78: static PetscErrorCode SNESSetFromOptions_NGMRES(SNES snes, PetscOptionItems PetscOptionsObject)
79: {
80: SNES_NGMRES *ngmres = (SNES_NGMRES *)snes->data;
81: PetscBool debug = PETSC_FALSE;
83: PetscFunctionBegin;
84: PetscOptionsHeadBegin(PetscOptionsObject, "SNES NGMRES options");
85: PetscCall(PetscOptionsEnum("-snes_ngmres_select_type", "Select type", "SNESNGMRESSetSelectType", SNESNGMRESSelectTypes, (PetscEnum)ngmres->select_type, (PetscEnum *)&ngmres->select_type, NULL));
86: PetscCall(PetscOptionsEnum("-snes_ngmres_restart_type", "Restart type", "SNESNGMRESSetRestartType", SNESNGMRESRestartTypes, (PetscEnum)ngmres->restart_type, (PetscEnum *)&ngmres->restart_type, NULL));
87: PetscCall(PetscOptionsBool("-snes_ngmres_candidate", "Use candidate storage", "SNES", ngmres->candidate, &ngmres->candidate, NULL));
88: PetscCall(PetscOptionsBool("-snes_ngmres_approxfunc", "Linearly approximate the function", "SNES", ngmres->approxfunc, &ngmres->approxfunc, NULL));
89: PetscCall(PetscOptionsInt("-snes_ngmres_m", "Number of directions", "SNES", ngmres->msize, &ngmres->msize, NULL));
90: PetscCall(PetscOptionsInt("-snes_ngmres_restart", "Iterations before forced restart", "SNES", ngmres->restart_periodic, &ngmres->restart_periodic, NULL));
91: PetscCall(PetscOptionsInt("-snes_ngmres_restart_it", "Tolerance iterations before restart", "SNES", ngmres->restart_it, &ngmres->restart_it, NULL));
92: PetscCall(PetscOptionsBool("-snes_ngmres_monitor", "Monitor actions of NGMRES", "SNES", ngmres->monitor ? PETSC_TRUE : PETSC_FALSE, &debug, NULL));
93: if (debug) ngmres->monitor = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes));
94: PetscCall(PetscOptionsReal("-snes_ngmres_gammaA", "Residual selection constant", "SNES", ngmres->gammaA, &ngmres->gammaA, NULL));
95: PetscCall(PetscOptionsReal("-snes_ngmres_gammaC", "Residual restart constant", "SNES", ngmres->gammaC, &ngmres->gammaC, NULL));
96: PetscCall(PetscOptionsReal("-snes_ngmres_epsilonB", "Difference selection constant", "SNES", ngmres->epsilonB, &ngmres->epsilonB, NULL));
97: PetscCall(PetscOptionsReal("-snes_ngmres_deltaB", "Difference residual selection constant", "SNES", ngmres->deltaB, &ngmres->deltaB, NULL));
98: PetscCall(PetscOptionsBool("-snes_ngmres_restart_fm_rise", "Restart on F_M residual rise", "SNESNGMRESSetRestartFmRise", ngmres->restart_fm_rise, &ngmres->restart_fm_rise, NULL));
99: PetscOptionsHeadEnd();
100: if (ngmres->gammaA > ngmres->gammaC && ngmres->gammaC > 2.) ngmres->gammaC = ngmres->gammaA;
101: if (ngmres->select_type == SNES_NGMRES_SELECT_LINESEARCH) {
102: PetscCall(SNESNGMRESGetAdditiveLineSearch_Private(snes, &ngmres->additive_linesearch));
103: PetscCall(SNESLineSearchSetFromOptions(ngmres->additive_linesearch));
104: }
105: PetscFunctionReturn(PETSC_SUCCESS);
106: }
108: PetscErrorCode SNESView_NGMRES(SNES snes, PetscViewer viewer)
109: {
110: SNES_NGMRES *ngmres = (SNES_NGMRES *)snes->data;
111: PetscBool isascii;
113: PetscFunctionBegin;
114: PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
115: if (isascii) {
116: PetscCall(PetscViewerASCIIPrintf(viewer, " Number of stored past updates: %" PetscInt_FMT "\n", ngmres->msize));
117: if (ngmres->select_type == SNES_NGMRES_SELECT_DIFFERENCE) {
118: PetscCall(PetscViewerASCIIPrintf(viewer, " Residual selection: gammaA=%1.0e, gammaC=%1.0e\n", (double)ngmres->gammaA, (double)ngmres->gammaC));
119: PetscCall(PetscViewerASCIIPrintf(viewer, " Difference restart: epsilonB=%1.0e, deltaB=%1.0e\n", (double)ngmres->epsilonB, (double)ngmres->deltaB));
120: PetscCall(PetscViewerASCIIPrintf(viewer, " Restart on F_M residual increase: %s\n", PetscBools[ngmres->restart_fm_rise]));
121: }
122: if (ngmres->additive_linesearch) {
123: PetscCall(PetscViewerASCIIPrintf(viewer, " Additive line-search details:\n"));
124: PetscCall(SNESLineSearchView(ngmres->additive_linesearch, viewer));
125: }
126: }
127: PetscFunctionReturn(PETSC_SUCCESS);
128: }
130: static PetscErrorCode SNESSolve_NGMRES(SNES snes)
131: {
132: SNES_NGMRES *ngmres = (SNES_NGMRES *)snes->data;
133: Vec X, F, B, D, Y; /* present solution, residual, and preconditioned residual */
134: Vec XA, FA, XM, FM; /* candidate linear combination answers */
135: PetscReal fnorm, fMnorm, fAnorm; /* coefficients and RHS to the minimization problem */
136: PetscReal xnorm, xMnorm, xAnorm;
137: PetscReal ynorm, yMnorm, yAnorm;
138: PetscInt k, k_restart, l, ivec, restart_count = 0;
139: PetscReal objmin, objM, objA, obj; /* support for objective functions minimization */
140: PetscBool selectRestart; /* solution selection data */
141: SNESConvergedReason reason;
142: SNESObjectiveFn *objective;
143: /*
144: These two variables are initialized to prevent compilers/analyzers from producing false warnings about these variables being passed
145: to SNESNGMRESSelect_Private() without being set when SNES_NGMRES_RESTART_DIFFERENCE, the values are not used in the subroutines in that case
146: so the code is correct as written.
147: */
148: PetscReal dnorm = 0.0, dminnorm = 0.0;
150: PetscFunctionBegin;
151: PetscCheck(!snes->xl && !snes->xu && !snes->ops->computevariablebounds, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_WRONGSTATE, "SNES solver %s does not support bounds", ((PetscObject)snes)->type_name);
153: PetscCall(PetscCitationsRegister(SNESCitation, &SNEScite));
154: /* variable initialization */
155: snes->reason = SNES_CONVERGED_ITERATING;
156: X = snes->vec_sol;
157: F = snes->vec_func;
158: B = snes->vec_rhs;
159: XA = snes->work[2];
160: FA = snes->work[0];
161: D = snes->work[1];
163: /* work for the line search */
164: Y = snes->vec_sol_update;
165: XM = snes->work[3];
166: FM = snes->work[4];
168: PetscCall(PetscObjectSAWsTakeAccess((PetscObject)snes));
169: snes->iter = 0;
170: snes->norm = 0.;
171: PetscCall(PetscObjectSAWsGrantAccess((PetscObject)snes));
173: /* initialization */
175: if (snes->npc && snes->npcside == PC_LEFT) {
176: PetscCall(SNESApplyNPC(snes, X, NULL, F));
177: PetscCall(SNESGetConvergedReason(snes->npc, &reason));
178: if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
179: snes->reason = SNES_DIVERGED_INNER;
180: PetscFunctionReturn(PETSC_SUCCESS);
181: }
182: } else {
183: if (!snes->vec_func_init_set) PetscCall(SNESComputeFunction(snes, X, F));
184: else snes->vec_func_init_set = PETSC_FALSE;
185: }
186: PetscCall(VecNorm(F, NORM_2, &fnorm));
187: SNESCheckFunctionDomainError(snes, fnorm);
188: PetscCall(SNESGetObjective(snes, &objective, NULL));
189: objmin = fnorm;
190: if (objective) {
191: PetscCall(SNESComputeObjective(snes, X, &objmin));
192: SNESCheckObjectiveDomainError(snes, objmin);
193: }
194: obj = objmin;
196: PetscCall(PetscObjectSAWsTakeAccess((PetscObject)snes));
197: snes->norm = fnorm;
198: PetscCall(PetscObjectSAWsGrantAccess((PetscObject)snes));
199: PetscCall(SNESLogConvergenceHistory(snes, fnorm, 0));
200: PetscCall(SNESConverged(snes, 0, 0.0, 0.0, fnorm));
201: PetscCall(SNESMonitor(snes, 0, fnorm));
202: if (snes->reason) PetscFunctionReturn(PETSC_SUCCESS);
203: PetscCall(SNESNGMRESUpdateSubspace_Private(snes, 0, 0, F, fnorm, X));
205: k_restart = 1;
206: l = 1;
207: ivec = 0;
208: for (k = 1; k < snes->max_its + 1; k++) {
209: /* Call general purpose update function */
210: PetscTryTypeMethod(snes, update, snes->iter);
212: /* Computation of x^M */
213: if (snes->npc && snes->npcside == PC_RIGHT) {
214: PetscCall(VecCopy(X, XM));
215: PetscCall(SNESSetInitialFunction(snes->npc, F));
217: PetscCall(PetscLogEventBegin(SNES_NPCSolve, snes->npc, XM, B, 0));
218: PetscCall(SNESSolve(snes->npc, B, XM));
219: PetscCall(PetscLogEventEnd(SNES_NPCSolve, snes->npc, XM, B, 0));
221: PetscCall(SNESGetConvergedReason(snes->npc, &reason));
222: if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
223: snes->reason = SNES_DIVERGED_INNER;
224: PetscFunctionReturn(PETSC_SUCCESS);
225: }
226: PetscCall(SNESGetNPCFunction(snes, FM, &fMnorm));
227: } else {
228: /* no preconditioner -- just take gradient descent with line search */
229: PetscCall(VecCopy(F, Y));
230: PetscCall(VecCopy(F, FM));
231: PetscCall(VecCopy(X, XM));
233: fMnorm = fnorm;
235: PetscCall(SNESLineSearchApply(snes->linesearch, XM, FM, &fMnorm, Y));
236: if (snes->reason) PetscFunctionReturn(PETSC_SUCCESS);
237: }
238: if (objective) {
239: PetscCall(SNESComputeObjective(snes, XM, &objM));
240: SNESCheckObjectiveDomainError(snes, objM);
241: } else objM = fMnorm;
242: objmin = PetscMin(objmin, objM);
244: PetscCall(SNESNGMRESFormCombinedSolution_Private(snes, ivec, l, XM, FM, fMnorm, X, XA, FA));
246: /* differences for selection and restart */
247: if (ngmres->restart_type == SNES_NGMRES_RESTART_DIFFERENCE || ngmres->select_type == SNES_NGMRES_SELECT_DIFFERENCE) {
248: PetscCall(SNESNGMRESNorms_Private(snes, l, X, F, XM, FM, XA, FA, D, &dnorm, &dminnorm, &xMnorm, NULL, &yMnorm, &xAnorm, &fAnorm, &yAnorm));
249: } else {
250: PetscCall(SNESNGMRESNorms_Private(snes, l, X, F, XM, FM, XA, FA, D, NULL, NULL, &xMnorm, NULL, &yMnorm, &xAnorm, &fAnorm, &yAnorm));
251: }
252: SNESCheckFunctionDomainError(snes, fnorm);
253: if (objective) {
254: PetscCall(SNESComputeObjective(snes, XA, &objA));
255: SNESCheckObjectiveDomainError(snes, objA);
256: } else objA = fAnorm;
258: /* combination (additive) or selection (multiplicative) of the N-GMRES solution */
259: PetscCall(SNESNGMRESSelect_Private(snes, k_restart, XM, FM, xMnorm, fMnorm, yMnorm, objM, XA, FA, xAnorm, fAnorm, yAnorm, objA, dnorm, objmin, dminnorm, X, F, Y, &xnorm, &fnorm, &ynorm));
260: SNESCheckFunctionDomainError(snes, fnorm);
261: if (objective) {
262: PetscCall(SNESComputeObjective(snes, X, &obj));
263: SNESCheckObjectiveDomainError(snes, obj);
264: } else obj = fnorm;
265: selectRestart = PETSC_FALSE;
267: if (ngmres->restart_type == SNES_NGMRES_RESTART_DIFFERENCE) {
268: PetscCall(SNESNGMRESSelectRestart_Private(snes, l, obj, objM, objA, dnorm, objmin, dminnorm, &selectRestart));
270: /* if the restart conditions persist for more than restart_it iterations, restart. */
271: if (selectRestart) restart_count++;
272: else restart_count = 0;
273: } else if (ngmres->restart_type == SNES_NGMRES_RESTART_PERIODIC) {
274: if (k_restart > ngmres->restart_periodic) {
275: if (ngmres->monitor) PetscCall(PetscViewerASCIIPrintf(ngmres->monitor, "periodic restart after %" PetscInt_FMT " iterations\n", k_restart));
276: restart_count = ngmres->restart_it;
277: }
278: }
280: ivec = k_restart % ngmres->msize; /* replace the last used part of the subspace */
282: /* restart after restart conditions have persisted for a fixed number of iterations */
283: if (restart_count >= ngmres->restart_it) {
284: if (ngmres->monitor) PetscCall(PetscViewerASCIIPrintf(ngmres->monitor, "Restarted at iteration %" PetscInt_FMT "\n", k_restart));
285: restart_count = 0;
286: k_restart = 1;
287: l = 1;
288: ivec = 0;
289: /* q_{00} = nu */
290: PetscCall(SNESNGMRESUpdateSubspace_Private(snes, 0, 0, FM, fMnorm, XM));
291: } else {
292: /* select the current size of the subspace */
293: if (l < ngmres->msize) l++;
294: k_restart++;
295: /* place the current entry in the list of previous entries */
296: if (ngmres->candidate) {
297: objmin = PetscMin(objmin, objM);
298: PetscCall(SNESNGMRESUpdateSubspace_Private(snes, ivec, l, FM, fMnorm, XM));
299: } else {
300: objmin = PetscMin(objmin, obj);
301: PetscCall(SNESNGMRESUpdateSubspace_Private(snes, ivec, l, F, fnorm, X));
302: }
303: }
305: PetscCall(PetscObjectSAWsTakeAccess((PetscObject)snes));
306: snes->iter = k;
307: snes->norm = fnorm;
308: snes->ynorm = ynorm;
309: snes->xnorm = xnorm;
310: PetscCall(PetscObjectSAWsGrantAccess((PetscObject)snes));
311: PetscCall(SNESLogConvergenceHistory(snes, snes->norm, snes->iter));
312: PetscCall(SNESConverged(snes, snes->iter, 0, 0, fnorm));
313: PetscCall(SNESMonitor(snes, snes->iter, snes->norm));
314: if (snes->reason) PetscFunctionReturn(PETSC_SUCCESS);
315: }
316: snes->reason = SNES_DIVERGED_MAX_IT;
317: PetscFunctionReturn(PETSC_SUCCESS);
318: }
320: /*@
321: SNESNGMRESSetRestartFmRise - Increase the restart count if the step x_M increases the residual F_M inside a `SNESNGMRES` solve
323: Input Parameters:
324: + snes - the `SNES` context.
325: - flg - boolean value deciding whether to use the option or not, default is `PETSC_FALSE`
327: Options Database Key:
328: . -snes_ngmres_restart_fm_rise - Increase the restart count if the step x_M increases the residual F_M
330: Level: advanced
332: Notes:
333: If the proposed step x_M increases the residual F_M, it might be trying to get out of a stagnation area.
334: To help the solver do that, remove the current stored solutions and residuals whenever F_M increases.
336: This option must be used with the `SNESNGMRES` `SNESNGMRESRestartType` of `SNES_NGMRES_RESTART_DIFFERENCE`
338: .seealso: [](ch_snes), `SNES`, `SNES_NGMRES_RESTART_DIFFERENCE`, `SNESNGMRES`, `SNESNGMRESRestartType`, `SNESNGMRESSetRestartType()`
339: @*/
340: PetscErrorCode SNESNGMRESSetRestartFmRise(SNES snes, PetscBool flg)
341: {
342: PetscErrorCode (*f)(SNES, PetscBool);
344: PetscFunctionBegin;
345: PetscCall(PetscObjectQueryFunction((PetscObject)snes, "SNESNGMRESSetRestartFmRise_C", &f));
346: if (f) PetscCall((f)(snes, flg));
347: PetscFunctionReturn(PETSC_SUCCESS);
348: }
350: static PetscErrorCode SNESNGMRESSetRestartFmRise_NGMRES(SNES snes, PetscBool flg)
351: {
352: SNES_NGMRES *ngmres = (SNES_NGMRES *)snes->data;
354: PetscFunctionBegin;
355: ngmres->restart_fm_rise = flg;
356: PetscFunctionReturn(PETSC_SUCCESS);
357: }
359: PetscErrorCode SNESNGMRESGetRestartFmRise(SNES snes, PetscBool *flg)
360: {
361: PetscErrorCode (*f)(SNES, PetscBool *);
363: PetscFunctionBegin;
364: PetscCall(PetscObjectQueryFunction((PetscObject)snes, "SNESNGMRESGetRestartFmRise_C", &f));
365: if (f) PetscCall((f)(snes, flg));
366: PetscFunctionReturn(PETSC_SUCCESS);
367: }
369: static PetscErrorCode SNESNGMRESGetRestartFmRise_NGMRES(SNES snes, PetscBool *flg)
370: {
371: SNES_NGMRES *ngmres = (SNES_NGMRES *)snes->data;
373: PetscFunctionBegin;
374: *flg = ngmres->restart_fm_rise;
375: PetscFunctionReturn(PETSC_SUCCESS);
376: }
378: /*@
379: SNESNGMRESSetRestartType - Sets the restart type for `SNESNGMRES`.
381: Logically Collective
383: Input Parameters:
384: + snes - the iterative context
385: - rtype - restart type, see `SNESNGMRESRestartType`
387: Options Database Keys:
388: + -snes_ngmres_restart_type<difference,periodic,none> - set the restart type
389: - -snes_ngmres_restart <30> - sets the number of iterations before restart for periodic
391: Level: intermediate
393: .seealso: [](ch_snes), `SNES`, `SNES_NGMRES_RESTART_DIFFERENCE`, `SNESNGMRES`, `SNESNGMRESRestartType`, `SNESNGMRESSetRestartFmRise()`,
394: `SNESNGMRESSetSelectType()`
395: @*/
396: PetscErrorCode SNESNGMRESSetRestartType(SNES snes, SNESNGMRESRestartType rtype)
397: {
398: PetscFunctionBegin;
400: PetscTryMethod(snes, "SNESNGMRESSetRestartType_C", (SNES, SNESNGMRESRestartType), (snes, rtype));
401: PetscFunctionReturn(PETSC_SUCCESS);
402: }
404: /*@
405: SNESNGMRESSetSelectType - Sets the selection type for `SNESNGMRES`. This determines how the candidate solution and
406: combined solution are used to create the next iterate.
408: Logically Collective
410: Input Parameters:
411: + snes - the iterative context
412: - stype - selection type, see `SNESNGMRESSelectType`
414: Options Database Key:
415: . -snes_ngmres_select_type<difference,none,linesearch> - select type
417: Level: intermediate
419: Note:
420: The default line search used is the `SNESLINESEARCHSECANT` line search and it requires two additional function evaluations.
422: .seealso: [](ch_snes), `SNES`, `SNESNGMRES`, `SNESNGMRESSelectType`, `SNES_NGMRES_SELECT_NONE`, `SNES_NGMRES_SELECT_DIFFERENCE`, `SNES_NGMRES_SELECT_LINESEARCH`,
423: `SNESNGMRESSetRestartType()`
424: @*/
425: PetscErrorCode SNESNGMRESSetSelectType(SNES snes, SNESNGMRESSelectType stype)
426: {
427: PetscFunctionBegin;
429: PetscTryMethod(snes, "SNESNGMRESSetSelectType_C", (SNES, SNESNGMRESSelectType), (snes, stype));
430: PetscFunctionReturn(PETSC_SUCCESS);
431: }
433: static PetscErrorCode SNESNGMRESSetSelectType_NGMRES(SNES snes, SNESNGMRESSelectType stype)
434: {
435: SNES_NGMRES *ngmres = (SNES_NGMRES *)snes->data;
437: PetscFunctionBegin;
438: ngmres->select_type = stype;
439: PetscFunctionReturn(PETSC_SUCCESS);
440: }
442: static PetscErrorCode SNESNGMRESSetRestartType_NGMRES(SNES snes, SNESNGMRESRestartType rtype)
443: {
444: SNES_NGMRES *ngmres = (SNES_NGMRES *)snes->data;
446: PetscFunctionBegin;
447: ngmres->restart_type = rtype;
448: PetscFunctionReturn(PETSC_SUCCESS);
449: }
451: /*MC
452: SNESNGMRES - An implementation of the Nonlinear Generalized Minimum Residual method, Nonlinear GMRES, or N-GMRES {cite}`ow1`, {cite}`bruneknepleysmithtu15` for solving
453: nonlinear systems with `SNES`.
455: Level: beginner
457: Options Database Keys:
458: + -snes_ngmres_select_type<difference,none,linesearch> - choose the select between candidate and combined solution
459: . -snes_ngmres_restart_type<difference,none,periodic> - choose the restart conditions
460: . -snes_ngmres_candidate - Use `SNESNGMRES` variant which combines candidate solutions instead of actual solutions
461: . -snes_ngmres_m - Number of stored previous solutions and residuals
462: . -snes_ngmres_restart_it - Number of iterations the restart conditions hold before restart
463: . -snes_ngmres_gammaA - Residual tolerance for solution select between the candidate and combination
464: . -snes_ngmres_gammaC - Residual tolerance for restart
465: . -snes_ngmres_epsilonB - Difference tolerance between subsequent solutions triggering restart
466: . -snes_ngmres_deltaB - Difference tolerance between residuals triggering restart
467: . -snes_ngmres_restart_fm_rise - Restart on residual rise from $x_M$ step
468: . -snes_ngmres_monitor - Prints relevant information about the nonlinear GNMRES iterations
469: . -snes_linesearch_type <basic,l2,cp> - Line search type used for the default smoother
470: - -snes_ngmres_additive_snes_linesearch_type - line search type used to select between the candidate and combined solution with additive select type
472: Notes:
473: The N-GMRES method combines m previous solutions into a minimum-residual solution by solving a small linearized
474: optimization problem at each iteration.
476: Very similar to the `SNESANDERSON` algorithm.
478: Unlike the linear GMRES algorithm this algorithm does not compute a Krylov subspace using the Arnoldi process. Instead it stores a
479: collection of previous solutions and the residuals $ F(x) - b $ at those solutions.
481: This algorithm ignores any Jacobian provided with `SNESSetJacobian()`
483: Only supports left non-linear preconditioning.
485: .seealso: [](ch_snes), `SNESCreate()`, `SNES`, `SNESSetType()`, `SNESType`, `SNESANDERSON`, `SNESNGMRESSetSelectType()`, `SNESNGMRESSetRestartType()`,
486: `SNESNGMRESSetRestartFmRise()`, `SNESNGMRESSelectType`, `SNESNGMRESRestartType`
487: M*/
489: PETSC_EXTERN PetscErrorCode SNESCreate_NGMRES(SNES snes)
490: {
491: SNES_NGMRES *ngmres;
492: SNESLineSearch linesearch;
494: PetscFunctionBegin;
495: snes->ops->destroy = SNESDestroy_NGMRES;
496: snes->ops->setup = SNESSetUp_NGMRES;
497: snes->ops->setfromoptions = SNESSetFromOptions_NGMRES;
498: snes->ops->view = SNESView_NGMRES;
499: snes->ops->solve = SNESSolve_NGMRES;
500: snes->ops->reset = SNESReset_NGMRES;
502: snes->usesnpc = PETSC_TRUE;
503: snes->usesksp = PETSC_FALSE;
504: snes->npcside = PC_RIGHT;
506: snes->alwayscomputesfinalresidual = PETSC_TRUE;
508: PetscCall(PetscNew(&ngmres));
509: snes->data = (void *)ngmres;
510: ngmres->msize = 30;
512: PetscCall(SNESParametersInitialize(snes));
513: PetscObjectParameterSetDefault(snes, max_funcs, 30000);
514: PetscObjectParameterSetDefault(snes, max_its, 10000);
516: ngmres->candidate = PETSC_FALSE;
518: PetscCall(SNESGetLineSearch(snes, &linesearch));
519: if (!((PetscObject)linesearch)->type_name) PetscCall(SNESLineSearchSetType(linesearch, SNESLINESEARCHBASIC));
521: ngmres->additive_linesearch = NULL;
522: ngmres->approxfunc = PETSC_FALSE;
523: ngmres->restart_it = 2;
524: ngmres->restart_periodic = 30;
525: ngmres->gammaA = 2.0;
526: ngmres->gammaC = 2.0;
527: ngmres->deltaB = 0.9;
528: ngmres->epsilonB = 0.1;
529: ngmres->restart_fm_rise = PETSC_FALSE;
531: ngmres->restart_type = SNES_NGMRES_RESTART_DIFFERENCE;
532: ngmres->select_type = SNES_NGMRES_SELECT_DIFFERENCE;
534: PetscCall(PetscObjectComposeFunction((PetscObject)snes, "SNESNGMRESSetSelectType_C", SNESNGMRESSetSelectType_NGMRES));
535: PetscCall(PetscObjectComposeFunction((PetscObject)snes, "SNESNGMRESSetRestartType_C", SNESNGMRESSetRestartType_NGMRES));
536: PetscCall(PetscObjectComposeFunction((PetscObject)snes, "SNESNGMRESSetRestartFmRise_C", SNESNGMRESSetRestartFmRise_NGMRES));
537: PetscCall(PetscObjectComposeFunction((PetscObject)snes, "SNESNGMRESGetRestartFmRise_C", SNESNGMRESGetRestartFmRise_NGMRES));
538: PetscFunctionReturn(PETSC_SUCCESS);
539: }