Actual source code: iterativ.c

  1: /*
  2:    This file contains some simple default routines.
  3:    These routines should be SHORT, since they will be included in every
  4:    executable image that uses the iterative routines (note that, through
  5:    the registry system, we provide a way to load only the truly necessary
  6:    files)
  7:  */
  8: #include <petsc/private/kspimpl.h>
  9: #include <petscdmshell.h>
 10: #include <petscdraw.h>

 12: /*@
 13:    KSPGetResidualNorm - Gets the last (possibly approximate and/or preconditioned) residual norm that has been computed.

 15:    Not Collective

 17:    Input Parameter:
 18: .  ksp - the iterative context

 20:    Output Parameter:
 21: .  rnorm - residual norm

 23:    Level: intermediate

 25:    Note:
 26:    For some methods, such as `KSPGMRES`, the norm is not computed directly from the residual.

 28:    The type of norm used by the method can be controlled with `KSPSetNormType()`

 30: .seealso: [](chapter_ksp), `KSP`, `KSPSetNormType()`, `KSPBuildResidual()`, `KSPNormType`
 31: @*/
 32: PetscErrorCode KSPGetResidualNorm(KSP ksp, PetscReal *rnorm)
 33: {
 34:   PetscFunctionBegin;
 37:   *rnorm = ksp->rnorm;
 38:   PetscFunctionReturn(PETSC_SUCCESS);
 39: }

 41: /*@
 42:    KSPGetIterationNumber - Gets the current iteration number; if the `KSPSolve()` is complete, returns the number of iterations used.

 44:    Not Collective

 46:    Input Parameter:
 47: .  ksp - the iterative context

 49:    Output Parameter:
 50: .  its - number of iterations

 52:    Level: intermediate

 54:    Note:
 55:    During the ith iteration this returns i-1

 57: .seealso: [](chapter_ksp), `KSP`, `KSPGetResidualNorm()`, `KSPBuildResidual()`, `KSPGetResidualNorm()`, `KSPGetTotalIterations()`
 58: @*/
 59: PetscErrorCode KSPGetIterationNumber(KSP ksp, PetscInt *its)
 60: {
 61:   PetscFunctionBegin;
 64:   *its = ksp->its;
 65:   PetscFunctionReturn(PETSC_SUCCESS);
 66: }

 68: /*@
 69:    KSPGetTotalIterations - Gets the total number of iterations this `KSP` object has performed since was created, counted over all linear solves

 71:    Not Collective

 73:    Input Parameter:
 74: .  ksp - the iterative context

 76:    Output Parameter:
 77: .  its - total number of iterations

 79:    Level: intermediate

 81:    Note:
 82:     Use `KSPGetIterationNumber()` to get the count for the most recent solve only
 83:    If this is called within a `KSPSolve()` (such as in a `KSPMonitor` routine) then it does not include iterations within that current solve

 85: .seealso: [](chapter_ksp), `KSP`, `KSPBuildResidual()`, `KSPGetResidualNorm()`, `KSPGetIterationNumber()`
 86: @*/
 87: PetscErrorCode KSPGetTotalIterations(KSP ksp, PetscInt *its)
 88: {
 89:   PetscFunctionBegin;
 92:   *its = ksp->totalits;
 93:   PetscFunctionReturn(PETSC_SUCCESS);
 94: }

 96: /*@C
 97:   KSPMonitorResidual - Print the (possibly preconditioned) residual norm at each iteration of an iterative solver.

 99:   Collective

101:   Input Parameters:
102: + ksp   - iterative context
103: . n     - iteration number
104: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
105: - vf    - The viewer context

107:   Options Database Key:
108: . -ksp_monitor - Activates `KSPMonitorResidual()`

110:   Level: intermediate

112:   Note:
113:   For some methods, such as `KSPGMRES`, the norm is not computed directly from the residual.

115:   The type of norm used by the method can be controlled with `KSPSetNormType()`

117:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
118:   to be used during the KSP solve.

120: .seealso: [](chapter_ksp), `KSP`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `KSPMonitorResidualDraw()`, `KSPMonitorResidualDrawLG()`,
121:           `KSPMonitorResidualRange()`, `KSPMonitorTrueResidualDraw()`, `KSPMonitorTrueResidualDrawLG()`, `KSPMonitorTrueResidualMax()`,
122:           `KSPMonitorSingularValue()`, `KSPMonitorSolutionDrawLG()`, `KSPMonitorSolutionDraw()`, `KSPMonitorSolution()`,
123:           `KSPMonitorErrorDrawLG()`, `KSPMonitorErrorDraw()`, KSPMonitorError()`
124: @*/
125: PetscErrorCode KSPMonitorResidual(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
126: {
127:   PetscViewer       viewer = vf->viewer;
128:   PetscViewerFormat format = vf->format;
129:   PetscInt          tablevel;
130:   const char       *prefix;

132:   PetscFunctionBegin;
134:   PetscCall(PetscObjectGetTabLevel((PetscObject)ksp, &tablevel));
135:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ksp, &prefix));
136:   PetscCall(PetscViewerPushFormat(viewer, format));
137:   PetscCall(PetscViewerASCIIAddTab(viewer, tablevel));
138:   if (n == 0 && prefix) PetscCall(PetscViewerASCIIPrintf(viewer, "  Residual norms for %s solve.\n", prefix));
139:   PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP Residual norm %14.12e \n", n, (double)rnorm));
140:   PetscCall(PetscViewerASCIISubtractTab(viewer, tablevel));
141:   PetscCall(PetscViewerPopFormat(viewer));
142:   PetscFunctionReturn(PETSC_SUCCESS);
143: }

145: /*@C
146:   KSPMonitorResidualDraw - Plots the (possibly preconditioned) residual at each iteration of an iterative solver.

148:   Collective

150:   Input Parameters:
151: + ksp   - iterative context
152: . n     - iteration number
153: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
154: - vf    - The viewer context

156:   Options Database Key:
157: . -ksp_monitor draw - Activates `KSPMonitorResidualDraw()`

159:   Level: intermediate

161:   Note:
162:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
163:   to be used during the `KSP` solve.

165: .seealso: [](chapter_ksp), `KSP`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `KSPMonitorResidual()`, `KSPMonitorResidualDrawLG()`
166: @*/
167: PetscErrorCode KSPMonitorResidualDraw(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
168: {
169:   PetscViewer       viewer = vf->viewer;
170:   PetscViewerFormat format = vf->format;
171:   Vec               r;

173:   PetscFunctionBegin;
175:   PetscCall(PetscViewerPushFormat(viewer, format));
176:   PetscCall(KSPBuildResidual(ksp, NULL, NULL, &r));
177:   PetscCall(PetscObjectSetName((PetscObject)r, "Residual"));
178:   PetscCall(PetscObjectCompose((PetscObject)r, "__Vec_bc_zero__", (PetscObject)ksp));
179:   PetscCall(VecView(r, viewer));
180:   PetscCall(PetscObjectCompose((PetscObject)r, "__Vec_bc_zero__", NULL));
181:   PetscCall(VecDestroy(&r));
182:   PetscCall(PetscViewerPopFormat(viewer));
183:   PetscFunctionReturn(PETSC_SUCCESS);
184: }

186: /*@C
187:   KSPMonitorResidualDrawLG - Plots the (possibly preconditioned) residual norm at each iteration of an iterative solver.

189:   Collective

191:   Input Parameters:
192: + ksp   - iterative context
193: . n     - iteration number
194: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
195: - vf    - The viewer context

197:   Options Database Key:
198: . -ksp_monitor draw::draw_lg - Activates `KSPMonitorResidualDrawLG()`

200:   Level: intermediate

202:   Notes:
203:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
204:   to be used during the `KSP` solve.

206:   Use `KSPMonitorResidualDrawLGCreate()` to create the context used with this monitor

208: .seealso: [](chapter_ksp), `KSP`, `PETSCVIEWERDRAW`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `KSPMonitorResidualDraw()`, `KSPMonitorResidual()`
209: @*/
210: PetscErrorCode KSPMonitorResidualDrawLG(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
211: {
212:   PetscViewer        viewer = vf->viewer;
213:   PetscViewerFormat  format = vf->format;
214:   PetscDrawLG        lg     = vf->lg;
215:   KSPConvergedReason reason;
216:   PetscReal          x, y;

218:   PetscFunctionBegin;
221:   PetscCall(PetscViewerPushFormat(viewer, format));
222:   if (!n) PetscCall(PetscDrawLGReset(lg));
223:   x = (PetscReal)n;
224:   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
225:   else y = -15.0;
226:   PetscCall(PetscDrawLGAddPoint(lg, &x, &y));
227:   PetscCall(KSPGetConvergedReason(ksp, &reason));
228:   if (n <= 20 || !(n % 5) || reason) {
229:     PetscCall(PetscDrawLGDraw(lg));
230:     PetscCall(PetscDrawLGSave(lg));
231:   }
232:   PetscCall(PetscViewerPopFormat(viewer));
233:   PetscFunctionReturn(PETSC_SUCCESS);
234: }

236: /*@C
237:   KSPMonitorResidualDrawLGCreate - Creates the context for the (possibly preconditioned) residual norm monitor `KSPMonitorResidualDrawLG()`

239:   Collective

241:   Input Parameters:
242: + viewer - The `PetscViewer` of type `PETSCVIEWERDRAW`
243: . format - The viewer format
244: - ctx    - An optional user context

246:   Output Parameter:
247: . vf    - The viewer context

249:   Level: intermediate

251: .seealso: [](chapter_ksp), `KSP`, `PETSCVIEWERDRAW`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `KSPMonitorResidualDrawLG()`,
252:           `PetscViewerFormat`, `PetscViewer`, `PetscViewerAndFormat`
253: @*/
254: PetscErrorCode KSPMonitorResidualDrawLGCreate(PetscViewer viewer, PetscViewerFormat format, void *ctx, PetscViewerAndFormat **vf)
255: {
256:   PetscFunctionBegin;
257:   PetscCall(PetscViewerAndFormatCreate(viewer, format, vf));
258:   (*vf)->data = ctx;
259:   PetscCall(KSPMonitorLGCreate(PetscObjectComm((PetscObject)viewer), NULL, NULL, "Log Residual Norm", 1, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, &(*vf)->lg));
260:   PetscFunctionReturn(PETSC_SUCCESS);
261: }

263: /*
264:   This is the same as KSPMonitorResidual() except it prints fewer digits of the residual as the residual gets smaller.
265:   This is because the later digits are meaningless and are often different on different machines; by using this routine different
266:   machines will usually generate the same output.

268:   Deprecated: Intentionally has no manual page
269: */
270: PetscErrorCode KSPMonitorResidualShort(KSP ksp, PetscInt its, PetscReal fnorm, PetscViewerAndFormat *vf)
271: {
272:   PetscViewer       viewer = vf->viewer;
273:   PetscViewerFormat format = vf->format;
274:   PetscInt          tablevel;
275:   const char       *prefix;

277:   PetscFunctionBegin;
279:   PetscCall(PetscObjectGetTabLevel((PetscObject)ksp, &tablevel));
280:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ksp, &prefix));
281:   PetscCall(PetscViewerPushFormat(viewer, format));
282:   PetscCall(PetscViewerASCIIAddTab(viewer, tablevel));
283:   if (its == 0 && prefix) PetscCall(PetscViewerASCIIPrintf(viewer, "  Residual norms for %s solve.\n", prefix));
284:   if (fnorm > 1.e-9) PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP Residual norm %g \n", its, (double)fnorm));
285:   else if (fnorm > 1.e-11) PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP Residual norm %5.3e \n", its, (double)fnorm));
286:   else PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP Residual norm < 1.e-11\n", its));
287:   PetscCall(PetscViewerASCIISubtractTab(viewer, tablevel));
288:   PetscCall(PetscViewerPopFormat(viewer));
289:   PetscFunctionReturn(PETSC_SUCCESS);
290: }

292: PetscErrorCode KSPMonitorRange_Private(KSP ksp, PetscInt it, PetscReal *per)
293: {
294:   Vec                resid;
295:   const PetscScalar *r;
296:   PetscReal          rmax, pwork;
297:   PetscInt           i, n, N;

299:   PetscFunctionBegin;
300:   PetscCall(KSPBuildResidual(ksp, NULL, NULL, &resid));
301:   PetscCall(VecNorm(resid, NORM_INFINITY, &rmax));
302:   PetscCall(VecGetLocalSize(resid, &n));
303:   PetscCall(VecGetSize(resid, &N));
304:   PetscCall(VecGetArrayRead(resid, &r));
305:   pwork = 0.0;
306:   for (i = 0; i < n; ++i) pwork += (PetscAbsScalar(r[i]) > .20 * rmax);
307:   PetscCall(VecRestoreArrayRead(resid, &r));
308:   PetscCall(VecDestroy(&resid));
309:   PetscCall(MPIU_Allreduce(&pwork, per, 1, MPIU_REAL, MPIU_SUM, PetscObjectComm((PetscObject)ksp)));
310:   *per = *per / N;
311:   PetscFunctionReturn(PETSC_SUCCESS);
312: }

314: /*@C
315:   KSPMonitorResidualRange - Prints the percentage of residual elements that are more then 10 percent of the maximum value.

317:   Collective

319:   Input Parameters:
320: + ksp   - iterative context
321: . it    - iteration number
322: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
323: - vf    - The viewer context

325:   Options Database Key:
326: . -ksp_monitor_range - Activates `KSPMonitorResidualRange()`

328:   Level: intermediate

330:   Note:
331:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
332:   to be used during the `KSP` solve.

334: .seealso: [](chapter_ksp), `KSP`, `KSPMonitorSet()`, `KSPMonitorResidual()`
335: @*/
336: PetscErrorCode KSPMonitorResidualRange(KSP ksp, PetscInt it, PetscReal rnorm, PetscViewerAndFormat *vf)
337: {
338:   static PetscReal  prev;
339:   PetscViewer       viewer = vf->viewer;
340:   PetscViewerFormat format = vf->format;
341:   PetscInt          tablevel;
342:   const char       *prefix;
343:   PetscReal         perc, rel;

345:   PetscFunctionBegin;
347:   PetscCall(PetscObjectGetTabLevel((PetscObject)ksp, &tablevel));
348:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ksp, &prefix));
349:   PetscCall(PetscViewerPushFormat(viewer, format));
350:   PetscCall(PetscViewerASCIIAddTab(viewer, tablevel));
351:   if (!it) prev = rnorm;
352:   if (it == 0 && prefix) PetscCall(PetscViewerASCIIPrintf(viewer, "  Residual norms for %s solve.\n", prefix));
353:   PetscCall(KSPMonitorRange_Private(ksp, it, &perc));
354:   rel  = (prev - rnorm) / prev;
355:   prev = rnorm;
356:   PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP preconditioned resid norm %14.12e Percent values above 20 percent of maximum %5.2f relative decrease %5.2e ratio %5.2e \n", it, (double)rnorm, (double)(100.0 * perc), (double)rel, (double)(rel / perc)));
357:   PetscCall(PetscViewerASCIISubtractTab(viewer, tablevel));
358:   PetscCall(PetscViewerPopFormat(viewer));
359:   PetscFunctionReturn(PETSC_SUCCESS);
360: }

362: /*@C
363:   KSPMonitorTrueResidual - Prints the true residual norm, as well as the (possibly preconditioned) approximate residual norm, at each iteration of an iterative solver.

365:   Collective

367:   Input Parameters:
368: + ksp   - iterative context
369: . n     - iteration number
370: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
371: - vf    - The viewer context

373:   Options Database Key:
374: . -ksp_monitor_true_residual - Activates `KSPMonitorTrueResidual()`

376:   Level: intermediate

378:   Notes:
379:   When using right preconditioning, these values are equivalent.

381:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
382:   to be used during the `KSP` solve.

384: .seealso: [](chapter_ksp), `KSP`, `KSPMonitorSet()`, `KSPMonitorResidual()`, `KSPMonitorTrueResidualMaxNorm()`, `PetscViewerAndFormat`
385: @*/
386: PetscErrorCode KSPMonitorTrueResidual(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
387: {
388:   PetscViewer       viewer = vf->viewer;
389:   PetscViewerFormat format = vf->format;
390:   Vec               r;
391:   PetscReal         truenorm, bnorm;
392:   char              normtype[256];
393:   PetscInt          tablevel;
394:   const char       *prefix;

396:   PetscFunctionBegin;
398:   PetscCall(PetscObjectGetTabLevel((PetscObject)ksp, &tablevel));
399:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ksp, &prefix));
400:   PetscCall(PetscStrncpy(normtype, KSPNormTypes[ksp->normtype], sizeof(normtype)));
401:   PetscCall(PetscStrtolower(normtype));
402:   PetscCall(KSPBuildResidual(ksp, NULL, NULL, &r));
403:   PetscCall(VecNorm(r, NORM_2, &truenorm));
404:   PetscCall(VecNorm(ksp->vec_rhs, NORM_2, &bnorm));
405:   PetscCall(VecDestroy(&r));

407:   PetscCall(PetscViewerPushFormat(viewer, format));
408:   PetscCall(PetscViewerASCIIAddTab(viewer, tablevel));
409:   if (n == 0 && prefix) PetscCall(PetscViewerASCIIPrintf(viewer, "  Residual norms for %s solve.\n", prefix));
410:   PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP %s resid norm %14.12e true resid norm %14.12e ||r(i)||/||b|| %14.12e\n", n, normtype, (double)rnorm, (double)truenorm, (double)(truenorm / bnorm)));
411:   PetscCall(PetscViewerASCIISubtractTab(viewer, tablevel));
412:   PetscCall(PetscViewerPopFormat(viewer));
413:   PetscFunctionReturn(PETSC_SUCCESS);
414: }

416: /*@C
417:   KSPMonitorTrueResidualDraw - Plots the true residual at each iteration of an iterative solver.

419:   Collective

421:   Input Parameters:
422: + ksp   - iterative context
423: . n     - iteration number
424: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
425: - vf    - The viewer context of type `PETSCVIEWERDRAW`

427:   Options Database Key:
428: . -ksp_monitor_true_residual draw - Activates `KSPMonitorResidualDraw()`

430:   Level: intermediate

432:   Note:
433:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
434:   to be used during the `KSP` solve.

436: .seealso: [](chapter_ksp), `PETSCVIEWERDRAW`, `KSP`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `KSPMonitorResidual()`,
437:           `KSPMonitorTrueResidualDrawLG()`, `PetscViewerAndFormat`
438: @*/
439: PetscErrorCode KSPMonitorTrueResidualDraw(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
440: {
441:   PetscViewer       viewer = vf->viewer;
442:   PetscViewerFormat format = vf->format;
443:   Vec               r;

445:   PetscFunctionBegin;
447:   PetscCall(PetscViewerPushFormat(viewer, format));
448:   PetscCall(KSPBuildResidual(ksp, NULL, NULL, &r));
449:   PetscCall(PetscObjectSetName((PetscObject)r, "Residual"));
450:   PetscCall(PetscObjectCompose((PetscObject)r, "__Vec_bc_zero__", (PetscObject)ksp));
451:   PetscCall(VecView(r, viewer));
452:   PetscCall(PetscObjectCompose((PetscObject)r, "__Vec_bc_zero__", NULL));
453:   PetscCall(VecDestroy(&r));
454:   PetscCall(PetscViewerPopFormat(viewer));
455:   PetscFunctionReturn(PETSC_SUCCESS);
456: }

458: /*@C
459:   KSPMonitorTrueResidualDrawLG - Plots the true residual norm at each iteration of an iterative solver.

461:   Collective

463:   Input Parameters:
464: + ksp   - iterative context
465: . n     - iteration number
466: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
467: - vf    - The viewer context

469:   Options Database Key:
470: . -ksp_monitor_true_residual draw::draw_lg - Activates `KSPMonitorTrueResidualDrawLG()`

472:   Level: intermediate

474:   Notes:
475:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
476:   to be used during the `KSP` solve.

478:   Call `KSPMonitorTrueResidualDrawLGCreate()` to create the context needed for this monitor

480: .seealso: [](chapter_ksp), `PETSCVIEWERDRAW`, `KSP`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `KSPMonitorTrueResidualDraw()`, `KSPMonitorResidual`,
481:           `KSPMonitorTrueResidualDrawLGCreate()`
482: @*/
483: PetscErrorCode KSPMonitorTrueResidualDrawLG(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
484: {
485:   PetscViewer        viewer = vf->viewer;
486:   PetscViewerFormat  format = vf->format;
487:   PetscDrawLG        lg     = vf->lg;
488:   Vec                r;
489:   KSPConvergedReason reason;
490:   PetscReal          truenorm, x[2], y[2];

492:   PetscFunctionBegin;
495:   PetscCall(KSPBuildResidual(ksp, NULL, NULL, &r));
496:   PetscCall(VecNorm(r, NORM_2, &truenorm));
497:   PetscCall(VecDestroy(&r));
498:   PetscCall(PetscViewerPushFormat(viewer, format));
499:   if (!n) PetscCall(PetscDrawLGReset(lg));
500:   x[0] = (PetscReal)n;
501:   if (rnorm > 0.0) y[0] = PetscLog10Real(rnorm);
502:   else y[0] = -15.0;
503:   x[1] = (PetscReal)n;
504:   if (truenorm > 0.0) y[1] = PetscLog10Real(truenorm);
505:   else y[1] = -15.0;
506:   PetscCall(PetscDrawLGAddPoint(lg, x, y));
507:   PetscCall(KSPGetConvergedReason(ksp, &reason));
508:   if (n <= 20 || !(n % 5) || reason) {
509:     PetscCall(PetscDrawLGDraw(lg));
510:     PetscCall(PetscDrawLGSave(lg));
511:   }
512:   PetscCall(PetscViewerPopFormat(viewer));
513:   PetscFunctionReturn(PETSC_SUCCESS);
514: }

516: /*@C
517:   KSPMonitorTrueResidualDrawLGCreate - Creates the context for the true residual monitor `KSPMonitorTrueResidualDrawLG()`

519:   Collective

521:   Input Parameters:
522: + viewer - The `PetscViewer` of type `PETSCVIEWERDRAW`
523: . format - The viewer format
524: - ctx    - An optional user context

526:   Output Parameter:
527: . vf    - The viewer context

529:   Level: intermediate

531: .seealso: [](chapter_ksp), `PETSCVIEWERDRAW`, `KSP`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `PetscViewerAndFormat`
532: @*/
533: PetscErrorCode KSPMonitorTrueResidualDrawLGCreate(PetscViewer viewer, PetscViewerFormat format, void *ctx, PetscViewerAndFormat **vf)
534: {
535:   const char *names[] = {"preconditioned", "true"};

537:   PetscFunctionBegin;
538:   PetscCall(PetscViewerAndFormatCreate(viewer, format, vf));
539:   (*vf)->data = ctx;
540:   PetscCall(KSPMonitorLGCreate(PetscObjectComm((PetscObject)viewer), NULL, NULL, "Log Residual Norm", 2, names, PETSC_DECIDE, PETSC_DECIDE, 400, 300, &(*vf)->lg));
541:   PetscFunctionReturn(PETSC_SUCCESS);
542: }

544: /*@C
545:   KSPMonitorTrueResidualMax - Prints the true residual max norm at each iteration of an iterative solver.

547:   Collective

549:   Input Parameters:
550: + ksp   - iterative context
551: . n     - iteration number
552: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
553: - vf    - The viewer context

555:   Options Database Key:
556: . -ksp_monitor_true_residual_max - Activates `KSPMonitorTrueResidualMax()`

558:   Level: intermediate

560:   Note:
561:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
562:   to be used during the `KSP` solve.

564: .seealso: [](chapter_ksp), `KSP`, `KSPMonitorSet()`, `KSPMonitorResidual()`, `KSPMonitorTrueResidualMaxNorm()`
565: @*/
566: PetscErrorCode KSPMonitorTrueResidualMax(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
567: {
568:   PetscViewer       viewer = vf->viewer;
569:   PetscViewerFormat format = vf->format;
570:   Vec               r;
571:   PetscReal         truenorm, bnorm;
572:   char              normtype[256];
573:   PetscInt          tablevel;
574:   const char       *prefix;

576:   PetscFunctionBegin;
578:   PetscCall(PetscObjectGetTabLevel((PetscObject)ksp, &tablevel));
579:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ksp, &prefix));
580:   PetscCall(PetscStrncpy(normtype, KSPNormTypes[ksp->normtype], sizeof(normtype)));
581:   PetscCall(PetscStrtolower(normtype));
582:   PetscCall(KSPBuildResidual(ksp, NULL, NULL, &r));
583:   PetscCall(VecNorm(r, NORM_INFINITY, &truenorm));
584:   PetscCall(VecNorm(ksp->vec_rhs, NORM_INFINITY, &bnorm));
585:   PetscCall(VecDestroy(&r));

587:   PetscCall(PetscViewerPushFormat(viewer, format));
588:   PetscCall(PetscViewerASCIIAddTab(viewer, tablevel));
589:   if (n == 0 && prefix) PetscCall(PetscViewerASCIIPrintf(viewer, "  Residual norms for %s solve.\n", prefix));
590:   PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP %s true resid max norm %14.12e ||r(i)||/||b|| %14.12e\n", n, normtype, (double)truenorm, (double)(truenorm / bnorm)));
591:   PetscCall(PetscViewerASCIISubtractTab(viewer, tablevel));
592:   PetscCall(PetscViewerPopFormat(viewer));
593:   PetscFunctionReturn(PETSC_SUCCESS);
594: }

596: /*@C
597:   KSPMonitorError - Prints the error norm, as well as the (possibly preconditioned) residual norm, at each iteration of an iterative solver.

599:   Collective

601:   Input Parameters:
602: + ksp   - iterative context
603: . n     - iteration number
604: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
605: - vf    - The viewer context

607:   Options Database Key:
608: . -ksp_monitor_error - Activates `KSPMonitorError()`

610:   Level: intermediate

612:   Note:
613:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
614:   to be used during the `KSP` solve.

616: .seealso: [](chapter_ksp), `KSP`, `KSPMonitorSet()`, `KSPMonitorResidual()`, `KSPMonitorTrueResidualMaxNorm()`
617: @*/
618: PetscErrorCode KSPMonitorError(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
619: {
620:   PetscViewer       viewer = vf->viewer;
621:   PetscViewerFormat format = vf->format;
622:   DM                dm;
623:   Vec               sol;
624:   PetscReal        *errors;
625:   PetscInt          Nf, f;
626:   PetscInt          tablevel;
627:   const char       *prefix;

629:   PetscFunctionBegin;
631:   PetscCall(PetscObjectGetTabLevel((PetscObject)ksp, &tablevel));
632:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ksp, &prefix));
633:   PetscCall(KSPGetDM(ksp, &dm));
634:   PetscCall(DMGetNumFields(dm, &Nf));
635:   PetscCall(DMGetGlobalVector(dm, &sol));
636:   PetscCall(KSPBuildSolution(ksp, sol, NULL));
637:   /* TODO: Make a different monitor that flips sign for SNES, Newton system is A dx = -b, so we need to negate the solution */
638:   PetscCall(VecScale(sol, -1.0));
639:   PetscCall(PetscCalloc1(Nf, &errors));
640:   PetscCall(DMComputeError(dm, sol, errors, NULL));

642:   PetscCall(PetscViewerPushFormat(viewer, format));
643:   PetscCall(PetscViewerASCIIAddTab(viewer, tablevel));
644:   if (n == 0 && prefix) PetscCall(PetscViewerASCIIPrintf(viewer, "  Error norms for %s solve.\n", prefix));
645:   PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP Error norm %s", n, Nf > 1 ? "[" : ""));
646:   PetscCall(PetscViewerASCIIUseTabs(viewer, PETSC_FALSE));
647:   for (f = 0; f < Nf; ++f) {
648:     if (f > 0) PetscCall(PetscViewerASCIIPrintf(viewer, ", "));
649:     PetscCall(PetscViewerASCIIPrintf(viewer, "%14.12e", (double)errors[f]));
650:   }
651:   PetscCall(PetscViewerASCIIPrintf(viewer, "%s resid norm %14.12e\n", Nf > 1 ? "]" : "", (double)rnorm));
652:   PetscCall(PetscViewerASCIIUseTabs(viewer, PETSC_TRUE));
653:   PetscCall(PetscViewerASCIISubtractTab(viewer, tablevel));
654:   PetscCall(PetscViewerPopFormat(viewer));
655:   PetscCall(DMRestoreGlobalVector(dm, &sol));
656:   PetscFunctionReturn(PETSC_SUCCESS);
657: }

659: /*@C
660:   KSPMonitorErrorDraw - Plots the error at each iteration of an iterative solver.

662:   Collective

664:   Input Parameters:
665: + ksp   - iterative context
666: . n     - iteration number
667: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
668: - vf    - The viewer context

670:   Options Database Key:
671: . -ksp_monitor_error draw - Activates `KSPMonitorErrorDraw()`

673:   Level: intermediate

675:   Note:
676:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
677:   to be used during the `KSP` solve.

679: .seealso: [](chapter_ksp), `PETSCVIEWERDRAW`, `KSP`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `KSPMonitorErrorDrawLG()`
680: @*/
681: PetscErrorCode KSPMonitorErrorDraw(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
682: {
683:   PetscViewer       viewer = vf->viewer;
684:   PetscViewerFormat format = vf->format;
685:   DM                dm;
686:   Vec               sol, e;

688:   PetscFunctionBegin;
690:   PetscCall(PetscViewerPushFormat(viewer, format));
691:   PetscCall(KSPGetDM(ksp, &dm));
692:   PetscCall(DMGetGlobalVector(dm, &sol));
693:   PetscCall(KSPBuildSolution(ksp, sol, NULL));
694:   PetscCall(DMComputeError(dm, sol, NULL, &e));
695:   PetscCall(PetscObjectSetName((PetscObject)e, "Error"));
696:   PetscCall(PetscObjectCompose((PetscObject)e, "__Vec_bc_zero__", (PetscObject)ksp));
697:   PetscCall(VecView(e, viewer));
698:   PetscCall(PetscObjectCompose((PetscObject)e, "__Vec_bc_zero__", NULL));
699:   PetscCall(VecDestroy(&e));
700:   PetscCall(DMRestoreGlobalVector(dm, &sol));
701:   PetscCall(PetscViewerPopFormat(viewer));
702:   PetscFunctionReturn(PETSC_SUCCESS);
703: }

705: /*@C
706:   KSPMonitorErrorDrawLG - Plots the error and residual norm at each iteration of an iterative solver.

708:   Collective

710:   Input Parameters:
711: + ksp   - iterative context
712: . n     - iteration number
713: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
714: - vf    - The viewer context

716:   Options Database Key:
717: . -ksp_monitor_error draw::draw_lg - Activates `KSPMonitorTrueResidualDrawLG()`

719:   Level: intermediate

721:   Notes:
722:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
723:   to be used during the `KSP` solve.

725:   Call `KSPMonitorErrorDrawLGCreate()` to create the context used with this monitor

727: .seealso: [](chapter_ksp), `PETSCVIEWERDRAW`, `KSP`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `KSPMonitorErrorDraw()`
728: @*/
729: PetscErrorCode KSPMonitorErrorDrawLG(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
730: {
731:   PetscViewer        viewer = vf->viewer;
732:   PetscViewerFormat  format = vf->format;
733:   PetscDrawLG        lg     = vf->lg;
734:   DM                 dm;
735:   Vec                sol;
736:   KSPConvergedReason reason;
737:   PetscReal         *x, *errors;
738:   PetscInt           Nf, f;

740:   PetscFunctionBegin;
743:   PetscCall(KSPGetDM(ksp, &dm));
744:   PetscCall(DMGetNumFields(dm, &Nf));
745:   PetscCall(DMGetGlobalVector(dm, &sol));
746:   PetscCall(KSPBuildSolution(ksp, sol, NULL));
747:   /* TODO: Make a different monitor that flips sign for SNES, Newton system is A dx = -b, so we need to negate the solution */
748:   PetscCall(VecScale(sol, -1.0));
749:   PetscCall(PetscCalloc2(Nf + 1, &x, Nf + 1, &errors));
750:   PetscCall(DMComputeError(dm, sol, errors, NULL));

752:   PetscCall(PetscViewerPushFormat(viewer, format));
753:   if (!n) PetscCall(PetscDrawLGReset(lg));
754:   for (f = 0; f < Nf; ++f) {
755:     x[f]      = (PetscReal)n;
756:     errors[f] = errors[f] > 0.0 ? PetscLog10Real(errors[f]) : -15.;
757:   }
758:   x[Nf]      = (PetscReal)n;
759:   errors[Nf] = rnorm > 0.0 ? PetscLog10Real(rnorm) : -15.;
760:   PetscCall(PetscDrawLGAddPoint(lg, x, errors));
761:   PetscCall(KSPGetConvergedReason(ksp, &reason));
762:   if (n <= 20 || !(n % 5) || reason) {
763:     PetscCall(PetscDrawLGDraw(lg));
764:     PetscCall(PetscDrawLGSave(lg));
765:   }
766:   PetscCall(PetscViewerPopFormat(viewer));
767:   PetscFunctionReturn(PETSC_SUCCESS);
768: }

770: /*@C
771:   KSPMonitorErrorDrawLGCreate - Creates the context for the error and preconditioned residual plotter `KSPMonitorErrorDrawLG()`

773:   Collective

775:   Input Parameters:
776: + viewer - The `PetscViewer`
777: . format - The viewer format
778: - ctx    - An optional user context

780:   Output Parameter:
781: . vf    - The viewer context

783:   Level: intermediate

785: .seealso: [](chapter_ksp), `PETSCVIEWERDRAW`, `KSP`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `KSPMonitorErrorDrawLG()`, `KSPMonitorErrorDrawLG()`
786: @*/
787: PetscErrorCode KSPMonitorErrorDrawLGCreate(PetscViewer viewer, PetscViewerFormat format, void *ctx, PetscViewerAndFormat **vf)
788: {
789:   KSP      ksp = (KSP)ctx;
790:   DM       dm;
791:   char   **names;
792:   PetscInt Nf, f;

794:   PetscFunctionBegin;
795:   PetscCall(KSPGetDM(ksp, &dm));
796:   PetscCall(DMGetNumFields(dm, &Nf));
797:   PetscCall(PetscMalloc1(Nf + 1, &names));
798:   for (f = 0; f < Nf; ++f) {
799:     PetscObject disc;
800:     const char *fname;
801:     char        lname[PETSC_MAX_PATH_LEN];

803:     PetscCall(DMGetField(dm, f, NULL, &disc));
804:     PetscCall(PetscObjectGetName(disc, &fname));
805:     PetscCall(PetscStrncpy(lname, fname, PETSC_MAX_PATH_LEN));
806:     PetscCall(PetscStrlcat(lname, " Error", PETSC_MAX_PATH_LEN));
807:     PetscCall(PetscStrallocpy(lname, &names[f]));
808:   }
809:   PetscCall(PetscStrallocpy("residual", &names[Nf]));
810:   PetscCall(PetscViewerAndFormatCreate(viewer, format, vf));
811:   (*vf)->data = ctx;
812:   PetscCall(KSPMonitorLGCreate(PetscObjectComm((PetscObject)viewer), NULL, NULL, "Log Error Norm", Nf + 1, (const char **)names, PETSC_DECIDE, PETSC_DECIDE, 400, 300, &(*vf)->lg));
813:   for (f = 0; f <= Nf; ++f) PetscCall(PetscFree(names[f]));
814:   PetscCall(PetscFree(names));
815:   PetscFunctionReturn(PETSC_SUCCESS);
816: }

818: /*@C
819:   KSPMonitorSolution - Print the solution norm at each iteration of an iterative solver.

821:   Collective

823:   Input Parameters:
824: + ksp   - iterative context
825: . n     - iteration number
826: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
827: - vf    - The viewer context

829:   Options Database Key:
830: . -ksp_monitor_solution - Activates `KSPMonitorSolution()`

832:   Level: intermediate

834:   Note:
835:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
836:   to be used during the `KSP` solve.

838: .seealso: [](chapter_ksp), `KSPMonitorSet()`, `KSPMonitorTrueResidual()`
839: @*/
840: PetscErrorCode KSPMonitorSolution(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
841: {
842:   PetscViewer       viewer = vf->viewer;
843:   PetscViewerFormat format = vf->format;
844:   Vec               x;
845:   PetscReal         snorm;
846:   PetscInt          tablevel;
847:   const char       *prefix;

849:   PetscFunctionBegin;
851:   PetscCall(KSPBuildSolution(ksp, NULL, &x));
852:   PetscCall(VecNorm(x, NORM_2, &snorm));
853:   PetscCall(PetscObjectGetTabLevel((PetscObject)ksp, &tablevel));
854:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ksp, &prefix));
855:   PetscCall(PetscViewerPushFormat(viewer, format));
856:   PetscCall(PetscViewerASCIIAddTab(viewer, tablevel));
857:   if (n == 0 && prefix) PetscCall(PetscViewerASCIIPrintf(viewer, "  Solution norms for %s solve.\n", prefix));
858:   PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP Solution norm %14.12e \n", n, (double)snorm));
859:   PetscCall(PetscViewerASCIISubtractTab(viewer, tablevel));
860:   PetscCall(PetscViewerPopFormat(viewer));
861:   PetscFunctionReturn(PETSC_SUCCESS);
862: }

864: /*@C
865:   KSPMonitorSolutionDraw - Plots the solution at each iteration of an iterative solver.

867:   Collective

869:   Input Parameters:
870: + ksp   - iterative context
871: . n     - iteration number
872: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
873: - vf    - The viewer context

875:   Options Database Key:
876: . -ksp_monitor_solution draw - Activates `KSPMonitorSolutionDraw()`

878:   Level: intermediate

880:   Note:
881:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
882:   to be used during the `KSP` solve.

884: .seealso: [](chapter_ksp), `KSPMonitorSet()`, `KSPMonitorTrueResidual()`
885: @*/
886: PetscErrorCode KSPMonitorSolutionDraw(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
887: {
888:   PetscViewer       viewer = vf->viewer;
889:   PetscViewerFormat format = vf->format;
890:   Vec               x;

892:   PetscFunctionBegin;
894:   PetscCall(KSPBuildSolution(ksp, NULL, &x));
895:   PetscCall(PetscViewerPushFormat(viewer, format));
896:   PetscCall(PetscObjectSetName((PetscObject)x, "Solution"));
897:   PetscCall(PetscObjectCompose((PetscObject)x, "__Vec_bc_zero__", (PetscObject)ksp));
898:   PetscCall(VecView(x, viewer));
899:   PetscCall(PetscObjectCompose((PetscObject)x, "__Vec_bc_zero__", NULL));
900:   PetscCall(PetscViewerPopFormat(viewer));
901:   PetscFunctionReturn(PETSC_SUCCESS);
902: }

904: /*@C
905:   KSPMonitorSolutionDrawLG - Plots the solution norm at each iteration of an iterative solver.

907:   Collective

909:   Input Parameters:
910: + ksp   - iterative context
911: . n     - iteration number
912: . rnorm - 2-norm (preconditioned) residual value (may be estimated).
913: - vf    - The viewer context

915:   Options Database Key:
916: . -ksp_monitor_solution draw::draw_lg - Activates `KSPMonitorSolutionDrawLG()`

918:   Level: intermediate

920:   Notes:
921:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
922:   to be used during the `KSP` solve.

924:    Call `KSPMonitorSolutionDrawLGCreate()` to create the context needed with this monitor

926: .seealso: [](chapter_ksp), `KSP`, `KSPMonitorSet()`, `KSPMonitorTrueResidual()`, `KSPMonitorSolutionDrawLGCreate()`
927: @*/
928: PetscErrorCode KSPMonitorSolutionDrawLG(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
929: {
930:   PetscViewer        viewer = vf->viewer;
931:   PetscViewerFormat  format = vf->format;
932:   PetscDrawLG        lg     = vf->lg;
933:   Vec                u;
934:   KSPConvergedReason reason;
935:   PetscReal          snorm, x, y;

937:   PetscFunctionBegin;
940:   PetscCall(KSPBuildSolution(ksp, NULL, &u));
941:   PetscCall(VecNorm(u, NORM_2, &snorm));
942:   PetscCall(PetscViewerPushFormat(viewer, format));
943:   if (!n) PetscCall(PetscDrawLGReset(lg));
944:   x = (PetscReal)n;
945:   if (snorm > 0.0) y = PetscLog10Real(snorm);
946:   else y = -15.0;
947:   PetscCall(PetscDrawLGAddPoint(lg, &x, &y));
948:   PetscCall(KSPGetConvergedReason(ksp, &reason));
949:   if (n <= 20 || !(n % 5) || reason) {
950:     PetscCall(PetscDrawLGDraw(lg));
951:     PetscCall(PetscDrawLGSave(lg));
952:   }
953:   PetscCall(PetscViewerPopFormat(viewer));
954:   PetscFunctionReturn(PETSC_SUCCESS);
955: }

957: /*@C
958:   KSPMonitorSolutionDrawLGCreate - Creates the context for the `KSP` monitor `KSPMonitorSolutionDrawLG()`

960:   Collective

962:   Input Parameters:
963: + viewer - The `PetscViewer`
964: . format - The viewer format
965: - ctx    - An optional user context

967:   Output Parameter:
968: . vf    - The viewer context

970:   Level: intermediate

972:   Note:
973:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
974:   to be used during the `KSP` solve.

976: .seealso: [](chapter_ksp), `KSPMonitorSet()`, `KSPMonitorTrueResidual()`
977: @*/
978: PetscErrorCode KSPMonitorSolutionDrawLGCreate(PetscViewer viewer, PetscViewerFormat format, void *ctx, PetscViewerAndFormat **vf)
979: {
980:   PetscFunctionBegin;
981:   PetscCall(PetscViewerAndFormatCreate(viewer, format, vf));
982:   (*vf)->data = ctx;
983:   PetscCall(KSPMonitorLGCreate(PetscObjectComm((PetscObject)viewer), NULL, NULL, "Log Solution Norm", 1, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, &(*vf)->lg));
984:   PetscFunctionReturn(PETSC_SUCCESS);
985: }

987: /*@C
988:   KSPMonitorSingularValue - Prints the two norm of the true residual and estimation of the extreme singular values of the preconditioned problem at each iteration.

990:   Logically Collective

992:   Input Parameters:
993: + ksp   - the iterative context
994: . n     - the iteration
995: . rnorm - the two norm of the residual
996: - vf    - The viewer context

998:   Options Database Key:
999: . -ksp_monitor_singular_value - Activates `KSPMonitorSingularValue()`

1001:   Level: intermediate

1003:   Notes:
1004:   The `KSPCG` solver uses the Lanczos technique for eigenvalue computation,
1005:   while `KSPGMRES` uses the Arnoldi technique; other iterative methods do
1006:   not currently compute singular values.

1008:   This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
1009:   to be used during the `KSP` solve.

1011:   Call `KSPMonitorSingularValueCreate()` to create the context needed by this monitor

1013: .seealso: [](chapter_ksp), `KSP`, `KSPMonitorSet()`, `KSPComputeExtremeSingularValues()`, `KSPMonitorSingularValueCreate()`
1014: @*/
1015: PetscErrorCode KSPMonitorSingularValue(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
1016: {
1017:   PetscViewer       viewer = vf->viewer;
1018:   PetscViewerFormat format = vf->format;
1019:   PetscReal         emin, emax;
1020:   PetscInt          tablevel;
1021:   const char       *prefix;

1023:   PetscFunctionBegin;
1026:   PetscCall(PetscObjectGetTabLevel((PetscObject)ksp, &tablevel));
1027:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ksp, &prefix));
1028:   PetscCall(PetscViewerPushFormat(viewer, format));
1029:   PetscCall(PetscViewerASCIIAddTab(viewer, tablevel));
1030:   if (n == 0 && prefix) PetscCall(PetscViewerASCIIPrintf(viewer, "  Residual norms for %s solve.\n", prefix));
1031:   if (!ksp->calc_sings) {
1032:     PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP Residual norm %14.12e \n", n, (double)rnorm));
1033:   } else {
1034:     PetscCall(KSPComputeExtremeSingularValues(ksp, &emax, &emin));
1035:     PetscCall(PetscViewerASCIIPrintf(viewer, "%3" PetscInt_FMT " KSP Residual norm %14.12e %% max %14.12e min %14.12e max/min %14.12e\n", n, (double)rnorm, (double)emax, (double)emin, (double)(emax / emin)));
1036:   }
1037:   PetscCall(PetscViewerASCIISubtractTab(viewer, tablevel));
1038:   PetscCall(PetscViewerPopFormat(viewer));
1039:   PetscFunctionReturn(PETSC_SUCCESS);
1040: }

1042: /*@C
1043:   KSPMonitorSingularValueCreate - Creates the singular value monitor context needed by `KSPMonitorSingularValue()`

1045:   Collective

1047:   Input Parameters:
1048: + viewer - The PetscViewer
1049: . format - The viewer format
1050: - ctx    - An optional user context

1052:   Output Parameter:
1053: . vf    - The viewer context

1055:   Level: intermediate

1057: .seealso: [](chapter_ksp), `KSP`, `KSPMonitorSet()`, `KSPMonitorSingularValue()`, `PetscViewer`
1058: @*/
1059: PetscErrorCode KSPMonitorSingularValueCreate(PetscViewer viewer, PetscViewerFormat format, void *ctx, PetscViewerAndFormat **vf)
1060: {
1061:   KSP ksp = (KSP)ctx;

1063:   PetscFunctionBegin;
1064:   PetscCall(PetscViewerAndFormatCreate(viewer, format, vf));
1065:   (*vf)->data = ctx;
1066:   PetscCall(KSPSetComputeSingularValues(ksp, PETSC_TRUE));
1067:   PetscFunctionReturn(PETSC_SUCCESS);
1068: }

1070: /*@C
1071:    KSPMonitorDynamicToleranceCreate - Creates the context used by `KSPMonitorDynamicTolerance()`

1073:    Logically Collective

1075:    Output Parameter:
1076: .  ctx - a void pointer

1078:    Options Database Key:
1079: .   -sub_ksp_dynamic_tolerance <coef> - coefficient of dynamic tolerance for inner solver, default is 1.0

1081:    Level: advanced

1083:    Note:
1084:    Use before calling `KSPMonitorSet()` with `KSPMonitorDynamicTolerance()`

1086:    The default coefficient for the tolerance can be changed with `KSPMonitorDynamicToleranceSetCoefficient()`

1088: .seealso: [](sec_flexibleksp), `KSP`, `KSPMonitorDynamicTolerance()`, `KSPMonitorDynamicToleranceDestroy()`, `KSPMonitorDynamicToleranceSetCoefficient()`
1089: @*/
1090: PetscErrorCode KSPMonitorDynamicToleranceCreate(void *ctx)
1091: {
1092:   KSPDynTolCtx *scale;

1094:   PetscFunctionBegin;
1095:   PetscCall(PetscMalloc1(1, &scale));
1096:   scale->bnrm   = -1.0;
1097:   scale->coef   = 1.0;
1098:   *(void **)ctx = scale;
1099:   PetscFunctionReturn(PETSC_SUCCESS);
1100: }

1102: /*@C
1103:    KSPMonitorDynamicToleranceSetCoefficient - Sets the coefficient in the context used by `KSPMonitorDynamicTolerance()`

1105:    Logically Collective

1107:    Output Parameters:
1108: +  ctx - the context for `KSPMonitorDynamicTolerance()`
1109: -  coeff - the coefficient, default is 1.0

1111:    Options Database Key:
1112: .   -sub_ksp_dynamic_tolerance <coef> - coefficient of dynamic tolerance for inner solver, default is 1.0

1114:    Level: advanced

1116:    Note:
1117:    Use before calling `KSPMonitorSet()` and after `KSPMonitorDynamicToleranceCreate()`

1119: .seealso: [](sec_flexibleksp), `KSP`, `KSPMonitorDynamicTolerance()`, `KSPMonitorDynamicToleranceDestroy()`, `KSPMonitorDynamicToleranceCreate()`
1120: @*/
1121: PetscErrorCode KSPMonitorDynamicToleranceSetCoefficient(void *ctx, PetscReal coeff)
1122: {
1123:   KSPDynTolCtx *scale = (KSPDynTolCtx *)ctx;

1125:   PetscFunctionBegin;
1126:   scale->coef = coeff;
1127:   PetscFunctionReturn(PETSC_SUCCESS);
1128: }

1130: /*@C
1131:    KSPMonitorDynamicTolerance - A monitor that changes the inner tolerance of nested preconditioners in every outer iteration in an adaptive way.

1133:    Collective

1135:    Input Parameters:
1136: +  ksp   - iterative context
1137: .  n     - iteration number (not used)
1138: .  fnorm - the current residual norm
1139: -  ctx   - context used by monitor

1141:    Options Database Key:
1142: .   -sub_ksp_dynamic_tolerance <coef> - coefficient of dynamic tolerance for inner solver, default is 1.0

1144:    Level: advanced

1146:    Notes:
1147:    Applies for `PCKSP`, `PCBJACOBI`, and `PCDEFLATION` preconditioners

1149:    This may be useful for a flexible preconditioned Krylov method, such as `KSPFGMRES`, [](sec_flexibleksp) to
1150:    control the accuracy of the inner solves needed to guarantee convergence of the outer iterations.

1152:    This is not called directly by users, rather one calls `KSPMonitorSet()`, with this function as an argument, to cause the monitor
1153:    to be used during the `KSP` solve.

1155:    Use `KSPMonitorDynamicToleranceCreate()` and `KSPMonitorDynamicToleranceSetCoefficient()` to create the context needed by this
1156:    monitor function.

1158:    Pass the context and `KSPMonitorDynamicToleranceDestroy()` to `KSPMonitorSet()`

1160: .seealso: [](sec_flexibleksp), `KSP`, `KSPMonitorDynamicToleranceCreate()`, `KSPMonitorDynamicToleranceDestroy()`, `KSPMonitorDynamicToleranceSetCoefficient()`
1161: @*/
1162: PetscErrorCode KSPMonitorDynamicTolerance(KSP ksp, PetscInt its, PetscReal fnorm, void *dummy)
1163: {
1164:   PC            pc;
1165:   PetscReal     outer_rtol, outer_abstol, outer_dtol, inner_rtol;
1166:   PetscInt      outer_maxits, nksp, first, i;
1167:   KSPDynTolCtx *scale  = (KSPDynTolCtx *)dummy;
1168:   KSP          *subksp = NULL;
1169:   KSP           kspinner;
1170:   PetscBool     flg;

1172:   PetscFunctionBegin;
1173:   PetscCall(KSPGetPC(ksp, &pc));

1175:   /* compute inner_rtol */
1176:   if (scale->bnrm < 0.0) {
1177:     Vec b;
1178:     PetscCall(KSPGetRhs(ksp, &b));
1179:     PetscCall(VecNorm(b, NORM_2, &(scale->bnrm)));
1180:   }
1181:   PetscCall(KSPGetTolerances(ksp, &outer_rtol, &outer_abstol, &outer_dtol, &outer_maxits));
1182:   inner_rtol = PetscMin(scale->coef * scale->bnrm * outer_rtol / fnorm, 0.999);

1184:   /* if pc is ksp */
1185:   PetscCall(PetscObjectTypeCompare((PetscObject)pc, PCKSP, &flg));
1186:   if (flg) {
1187:     PetscCall(PCKSPGetKSP(pc, &kspinner));
1188:     PetscCall(KSPSetTolerances(kspinner, inner_rtol, outer_abstol, outer_dtol, outer_maxits));
1189:     PetscFunctionReturn(PETSC_SUCCESS);
1190:   }

1192:   /* if pc is bjacobi */
1193:   PetscCall(PetscObjectTypeCompare((PetscObject)pc, PCBJACOBI, &flg));
1194:   if (flg) {
1195:     PetscCall(PCBJacobiGetSubKSP(pc, &nksp, &first, &subksp));
1196:     if (subksp) {
1197:       for (i = 0; i < nksp; i++) PetscCall(KSPSetTolerances(subksp[i], inner_rtol, outer_abstol, outer_dtol, outer_maxits));
1198:       PetscFunctionReturn(PETSC_SUCCESS);
1199:     }
1200:   }

1202:   /* if pc is deflation*/
1203:   PetscCall(PetscObjectTypeCompare((PetscObject)pc, PCDEFLATION, &flg));
1204:   if (flg) {
1205:     PetscCall(PCDeflationGetCoarseKSP(pc, &kspinner));
1206:     PetscCall(KSPSetTolerances(kspinner, inner_rtol, outer_abstol, outer_dtol, PETSC_DEFAULT));
1207:     PetscFunctionReturn(PETSC_SUCCESS);
1208:   }

1210:   /* todo: dynamic tolerance may apply to other types of pc */
1211:   PetscFunctionReturn(PETSC_SUCCESS);
1212: }

1214: /*@C
1215:      KSPMonitorDynamicToleranceDestroy - Destroy the monitor context used in `KSPMonitorDynamicTolerance()`

1217:    Input Parameter:
1218: .   ctx - the monitor context

1220:    Level: advanced

1222:    Note:
1223:    This is not called directly but is passed to `KSPMonitorSet()` along with `KSPMonitorDynamicTolerance()`

1225: .seealso: `KSP`, `KSPMonitorDynamicTolerance()`, `KSPMonitorSet()`, `KSPMonitorDynamicToleranceCreate()`
1226: @*/
1227: PetscErrorCode KSPMonitorDynamicToleranceDestroy(void **ctx)
1228: {
1229:   PetscFunctionBegin;
1230:   PetscCall(PetscFree(*ctx));
1231:   PetscFunctionReturn(PETSC_SUCCESS);
1232: }

1234: /*@C
1235:    KSPConvergedSkip - Convergence test that do not return as converged
1236:    until the maximum number of iterations is reached.

1238:    Collective

1240:    Input Parameters:
1241: +  ksp   - iterative context
1242: .  n     - iteration number
1243: .  rnorm - 2-norm residual value (may be estimated)
1244: -  dummy - unused convergence context

1246:    Output Parameter:
1247: .  reason - `KSP_CONVERGED_ITERATING`, `KSP_CONVERGED_ITS`

1249:    Level: advanced

1251:    Notes:
1252:    This should be used as the convergence test with the option
1253:    `KSPSetNormType`(ksp,`KSP_NORM_NONE`), since norms of the residual are
1254:    not computed. Convergence is then declared after the maximum number
1255:    of iterations have been reached. Useful when one is using `KSPCG` or
1256:    `KSPBCGS`. [](sec_flexibleksp)

1258: .seealso: [](chapter_ksp), `KSP`, `KSPCG`, `KSPBCGS`, `KSPSetConvergenceTest()`, `KSPSetTolerances()`, `KSPSetNormType()`, [](sec_flexibleksp),
1259:           `KSPConvergedReason`
1260: @*/
1261: PetscErrorCode KSPConvergedSkip(KSP ksp, PetscInt n, PetscReal rnorm, KSPConvergedReason *reason, void *dummy)
1262: {
1263:   PetscFunctionBegin;
1266:   *reason = KSP_CONVERGED_ITERATING;
1267:   if (n >= ksp->max_it) *reason = KSP_CONVERGED_ITS;
1268:   PetscFunctionReturn(PETSC_SUCCESS);
1269: }

1271: /*@
1272:    KSPSetConvergedNegativeCurvature - Allows to declare convergence and return `KSP_CONVERGED_NEG_CURVE` when negative curvature is detected

1274:    Collective

1276:    Input Parameters:
1277: +  ksp   - iterative context
1278: -  flg   - the Boolean value

1280:    Options Database Key:
1281: .   -ksp_converged_neg_curve <bool> - Declare convergence if negative curvature is detected

1283:    Level: advanced

1285:    Notes:
1286:    This is currently used only by a subset of the Krylov solvers, namely `KSPCG`, `KSPSTCG`, `KSPQCG`, `KSPGLTR`, `KSPNASH`, and `KSPMINRES`.

1288: .seealso: [](chapter_ksp), `KSP`, `KSPConvergedReason`, `KSPGetConvergedNegativeCurvature()`
1289: @*/
1290: PetscErrorCode KSPSetConvergedNegativeCurvature(KSP ksp, PetscBool flg)
1291: {
1292:   PetscFunctionBegin;
1295:   ksp->converged_neg_curve = flg;
1296:   PetscFunctionReturn(PETSC_SUCCESS);
1297: }

1299: /*@
1300:    KSPGetConvergedNegativeCurvature - Get the flag to declare convergence if negative curvature is detected

1302:    Collective

1304:    Input Parameter:
1305: .  ksp   - iterative context

1307:    Output Parameter:
1308: .  flg   - the Boolean value

1310:    Level: advanced

1312: .seealso: [](chapter_ksp), `KSP`, `KSPConvergedReason`, `KSPSetConvergedNegativeCurvature()`
1313: @*/
1314: PetscErrorCode KSPGetConvergedNegativeCurvature(KSP ksp, PetscBool *flg)
1315: {
1316:   PetscFunctionBegin;
1319:   *flg = ksp->converged_neg_curve;
1320:   PetscFunctionReturn(PETSC_SUCCESS);
1321: }

1323: /*@C
1324:    KSPConvergedDefaultCreate - Creates and initializes the context used by the `KSPConvergedDefault()` function

1326:    Not Collective

1328:    Output Parameter:
1329: .  ctx - convergence context

1331:    Level: intermediate

1333: .seealso: [](chapter_ksp), `KSP`, `KSPConvergedDefault()`, `KSPConvergedDefaultDestroy()`, `KSPSetConvergenceTest()`, `KSPSetTolerances()`,
1334:           `KSPConvergedSkip()`, `KSPConvergedReason`, `KSPGetConvergedReason()`, `KSPConvergedDefaultSetUIRNorm()`, `KSPConvergedDefaultSetUMIRNorm()`,
1335:           `KSPConvergedDefaultSetConvergedMaxits()`
1336: @*/
1337: PetscErrorCode KSPConvergedDefaultCreate(void **ctx)
1338: {
1339:   KSPConvergedDefaultCtx *cctx;

1341:   PetscFunctionBegin;
1342:   PetscCall(PetscNew(&cctx));
1343:   *ctx = cctx;
1344:   PetscFunctionReturn(PETSC_SUCCESS);
1345: }

1347: /*@
1348:    KSPConvergedDefaultSetUIRNorm - makes the default convergence test use || B*(b - A*(initial guess))||
1349:       instead of || B*b ||. In the case of right preconditioner or if `KSPSetNormType`(ksp,`KSP_NORM_UNPRECONDITIONED`)
1350:       is used there is no B in the above formula. UIRNorm is short for Use Initial Residual Norm.

1352:    Collective

1354:    Input Parameters:
1355: .  ksp   - iterative context

1357:    Options Database Key:
1358: .   -ksp_converged_use_initial_residual_norm <bool> - Use initial residual norm for computing relative convergence

1360:    Level: intermediate

1362:    Notes:
1363:    Use `KSPSetTolerances()` to alter the defaults for rtol, abstol, dtol.

1365:    The precise values of reason are macros such as `KSP_CONVERGED_RTOL`, which
1366:    are defined in petscksp.h.

1368:    If the convergence test is not `KSPConvergedDefault()` then this is ignored.

1370:    If right preconditioning is being used then B does not appear in the above formula.

1372: .seealso: [](chapter_ksp), `KSP`, `KSPSetConvergenceTest()`, `KSPSetTolerances()`, `KSPConvergedSkip()`, `KSPConvergedReason`, `KSPGetConvergedReason()`, `KSPConvergedDefaultSetUMIRNorm()`, `KSPConvergedDefaultSetConvergedMaxits()`
1373: @*/
1374: PetscErrorCode KSPConvergedDefaultSetUIRNorm(KSP ksp)
1375: {
1376:   KSPConvergedDefaultCtx *ctx = (KSPConvergedDefaultCtx *)ksp->cnvP;

1378:   PetscFunctionBegin;
1380:   if (ksp->converged != KSPConvergedDefault) PetscFunctionReturn(PETSC_SUCCESS);
1381:   PetscCheck(!ctx->mininitialrtol, PetscObjectComm((PetscObject)ksp), PETSC_ERR_ARG_WRONGSTATE, "Cannot use KSPConvergedDefaultSetUIRNorm() and KSPConvergedDefaultSetUMIRNorm() together");
1382:   ctx->initialrtol = PETSC_TRUE;
1383:   PetscFunctionReturn(PETSC_SUCCESS);
1384: }

1386: /*@
1387:    KSPConvergedDefaultSetUMIRNorm - makes the default convergence test use min(|| B*(b - A*(initial guess))||,|| B*b ||)
1388:       In the case of right preconditioner or if `KSPSetNormType`(ksp,`KSP_NORM_UNPRECONDITIONED`)
1389:       is used there is no B in the above formula. UMIRNorm is short for Use Minimum Initial Residual Norm.

1391:    Collective

1393:    Input Parameters:
1394: .  ksp   - iterative context

1396:    Options Database Key:
1397: .   -ksp_converged_use_min_initial_residual_norm <bool> - Use minimum of initial residual norm and b for computing relative convergence

1399:    Level: intermediate

1401:    Use `KSPSetTolerances()` to alter the defaults for rtol, abstol, dtol.

1403:    The precise values of reason are macros such as `KSP_CONVERGED_RTOL`, which
1404:    are defined in petscksp.h.

1406: .seealso: [](chapter_ksp), `KSP`, `KSPSetConvergenceTest()`, `KSPSetTolerances()`, `KSPConvergedSkip()`, `KSPConvergedReason`, `KSPGetConvergedReason()`, `KSPConvergedDefaultSetUIRNorm()`, `KSPConvergedDefaultSetConvergedMaxits()`
1407: @*/
1408: PetscErrorCode KSPConvergedDefaultSetUMIRNorm(KSP ksp)
1409: {
1410:   KSPConvergedDefaultCtx *ctx = (KSPConvergedDefaultCtx *)ksp->cnvP;

1412:   PetscFunctionBegin;
1414:   if (ksp->converged != KSPConvergedDefault) PetscFunctionReturn(PETSC_SUCCESS);
1415:   PetscCheck(!ctx->initialrtol, PetscObjectComm((PetscObject)ksp), PETSC_ERR_ARG_WRONGSTATE, "Cannot use KSPConvergedDefaultSetUIRNorm() and KSPConvergedDefaultSetUMIRNorm() together");
1416:   ctx->mininitialrtol = PETSC_TRUE;
1417:   PetscFunctionReturn(PETSC_SUCCESS);
1418: }

1420: /*@
1421:    KSPConvergedDefaultSetConvergedMaxits - allows the default convergence test to declare convergence and return `KSP_CONVERGED_ITS` if the maximum number of iterations is reached

1423:    Collective

1425:    Input Parameters:
1426: +  ksp - iterative context
1427: -  flg - boolean flag

1429:    Options Database Key:
1430: .   -ksp_converged_maxits <bool> - Declare convergence if the maximum number of iterations is reached

1432:    Level: intermediate

1434:    Note:
1435:    The precise values of reason available in `KSPConvergedReason`

1437: .seealso: [](chapter_ksp), `KSP`, `KSPSetConvergenceTest()`, `KSPSetTolerances()`, `KSPConvergedSkip()`, `KSPConvergedReason`, `KSPGetConvergedReason()`, `KSPConvergedDefaultSetUMIRNorm()`, `KSPConvergedDefaultSetUIRNorm()`
1438: @*/
1439: PetscErrorCode KSPConvergedDefaultSetConvergedMaxits(KSP ksp, PetscBool flg)
1440: {
1441:   KSPConvergedDefaultCtx *ctx = (KSPConvergedDefaultCtx *)ksp->cnvP;

1443:   PetscFunctionBegin;
1446:   if (ksp->converged != KSPConvergedDefault) PetscFunctionReturn(PETSC_SUCCESS);
1447:   ctx->convmaxits = flg;
1448:   PetscFunctionReturn(PETSC_SUCCESS);
1449: }

1451: /*@C
1452:    KSPConvergedDefault - Default code to determine convergence of the linear iterative solvers

1454:    Collective

1456:    Input Parameters:
1457: +  ksp   - iterative context
1458: .  n     - iteration number
1459: .  rnorm - residual norm (may be estimated, depending on the method may be the preconditioned residual norm)
1460: -  ctx - convergence context which must be created by `KSPConvergedDefaultCreate()`

1462:    Output Parameter:
1463: .  reason - the convergence reason; it is positive if the iteration has converged,
1464:             negative if the iteration has diverged, and `KSP_CONVERGED_ITERATING` otherwise

1466:    Options Database Keys:
1467: +   -ksp_max_it - maximum number of linear iterations
1468: .   -ksp_rtol rtol - relative tolerance used in default determination of convergence, i.e. if residual norm decreases by this factor than convergence is declared
1469: .   -ksp_atol abstol - absolute tolerance used in default convergence test, i.e. if residual norm is less than this then convergence is declared
1470: .   -ksp_divtol tol - if residual norm increases by this factor than divergence is declared
1471: .   -ksp_converged_use_initial_residual_norm - see `KSPConvergedDefaultSetUIRNorm()`
1472: .   -ksp_converged_use_min_initial_residual_norm - see `KSPConvergedDefaultSetUMIRNorm()`
1473: -   -ksp_converged_maxits - see `KSPConvergedDefaultSetConvergedMaxits()`

1475:    Level: advanced

1477:    Notes:
1478:    `KSPConvergedDefault()` reaches convergence when   rnorm < MAX (rtol * rnorm_0, abstol);
1479:    Divergence is detected if rnorm > dtol * rnorm_0, or when failures are detected throughout the iteration.
1480:    By default, reaching the maximum number of iterations is considered divergence (i.e. KSP_DIVERGED_ITS).
1481:    In order to have PETSc declaring convergence in such a case (i.e. `KSP_CONVERGED_ITS`), users can use `KSPConvergedDefaultSetConvergedMaxits()`

1483:    where:
1484: +     rtol - relative tolerance,
1485: .     abstol - absolute tolerance.
1486: .     dtol - divergence tolerance,
1487: -     rnorm_0 - the two norm of the right hand side (or the preconditioned norm, depending on what was set with
1488:           `KSPSetNormType()`. When initial guess is non-zero you
1489:           can call `KSPConvergedDefaultSetUIRNorm()` to use the norm of (b - A*(initial guess))
1490:           as the starting point for relative norm convergence testing, that is as rnorm_0.
1491:           Call `KSPConvergedDefaultSetUMIRNorm()` to use the minimum of the norm of (b - A*(initial guess)) and the norm of b as the starting point.

1493:    Use `KSPSetTolerances()` to alter the defaults for rtol, abstol, dtol.

1495:    Use `KSPSetNormType()` (or -ksp_norm_type <none,preconditioned,unpreconditioned,natural>) to change the norm used for computing rnorm

1497:    The precise values of reason are available in `KSPConvergedReason`

1499:    This routine is used by `KSP` by default so the user generally never needs call it directly.

1501:    Use `KSPSetConvergenceTest()` to provide your own test instead of using this one.

1503:    Call `KSPSetConvergenceTest()` with the ctx, as created above and the destruction function `KSPConvergedDefaultDestroy()`

1505: .seealso: [](chapter_ksp), `KSP`, `KSPSetConvergenceTest()`, `KSPSetTolerances()`, `KSPConvergedSkip()`, `KSPConvergedReason`, `KSPGetConvergedReason()`,
1506:           `KSPConvergedDefaultSetUIRNorm()`, `KSPConvergedDefaultSetUMIRNorm()`, `KSPConvergedDefaultSetConvergedMaxits()`, `KSPConvergedDefaultCreate()`, `KSPConvergedDefaultDestroy()`
1507: @*/
1508: PetscErrorCode KSPConvergedDefault(KSP ksp, PetscInt n, PetscReal rnorm, KSPConvergedReason *reason, void *ctx)
1509: {
1510:   KSPConvergedDefaultCtx *cctx = (KSPConvergedDefaultCtx *)ctx;
1511:   KSPNormType             normtype;

1513:   PetscFunctionBegin;
1517:   PetscCheck(cctx, PetscObjectComm((PetscObject)ksp), PETSC_ERR_ARG_NULL, "Convergence context must have been created with KSPConvergedDefaultCreate()");
1518:   *reason = KSP_CONVERGED_ITERATING;

1520:   if (cctx->convmaxits && n >= ksp->max_it) {
1521:     *reason = KSP_CONVERGED_ITS;
1522:     PetscCall(PetscInfo(ksp, "Linear solver has converged. Maximum number of iterations reached %" PetscInt_FMT "\n", n));
1523:     PetscFunctionReturn(PETSC_SUCCESS);
1524:   }
1525:   PetscCall(KSPGetNormType(ksp, &normtype));
1526:   if (normtype == KSP_NORM_NONE) PetscFunctionReturn(PETSC_SUCCESS);

1528:   if (!n) {
1529:     /* if user gives initial guess need to compute norm of b */
1530:     if (!ksp->guess_zero && !cctx->initialrtol) {
1531:       PetscReal snorm = 0.0;
1532:       if (ksp->normtype == KSP_NORM_UNPRECONDITIONED || ksp->pc_side == PC_RIGHT) {
1533:         PetscCall(PetscInfo(ksp, "user has provided nonzero initial guess, computing 2-norm of RHS\n"));
1534:         PetscCall(VecNorm(ksp->vec_rhs, NORM_2, &snorm)); /*     <- b'*b */
1535:       } else {
1536:         Vec z;
1537:         /* Should avoid allocating the z vector each time but cannot stash it in cctx because if KSPReset() is called the vector size might change */
1538:         PetscCall(VecDuplicate(ksp->vec_rhs, &z));
1539:         PetscCall(KSP_PCApply(ksp, ksp->vec_rhs, z));
1540:         if (ksp->normtype == KSP_NORM_PRECONDITIONED) {
1541:           PetscCall(PetscInfo(ksp, "user has provided nonzero initial guess, computing 2-norm of preconditioned RHS\n"));
1542:           PetscCall(VecNorm(z, NORM_2, &snorm)); /*    dp <- b'*B'*B*b */
1543:         } else if (ksp->normtype == KSP_NORM_NATURAL) {
1544:           PetscScalar norm;
1545:           PetscCall(PetscInfo(ksp, "user has provided nonzero initial guess, computing natural norm of RHS\n"));
1546:           PetscCall(VecDot(ksp->vec_rhs, z, &norm));
1547:           snorm = PetscSqrtReal(PetscAbsScalar(norm)); /*    dp <- b'*B*b */
1548:         }
1549:         PetscCall(VecDestroy(&z));
1550:       }
1551:       /* handle special case of zero RHS and nonzero guess */
1552:       if (!snorm) {
1553:         PetscCall(PetscInfo(ksp, "Special case, user has provided nonzero initial guess and zero RHS\n"));
1554:         snorm = rnorm;
1555:       }
1556:       if (cctx->mininitialrtol) ksp->rnorm0 = PetscMin(snorm, rnorm);
1557:       else ksp->rnorm0 = snorm;
1558:     } else {
1559:       ksp->rnorm0 = rnorm;
1560:     }
1561:     ksp->ttol = PetscMax(ksp->rtol * ksp->rnorm0, ksp->abstol);
1562:   }

1564:   if (n <= ksp->chknorm) PetscFunctionReturn(PETSC_SUCCESS);

1566:   if (PetscIsInfOrNanReal(rnorm)) {
1567:     PCFailedReason pcreason;
1568:     PetscInt       sendbuf, recvbuf;
1569:     PetscCall(PCGetFailedReasonRank(ksp->pc, &pcreason));
1570:     sendbuf = (PetscInt)pcreason;
1571:     PetscCall(MPIU_Allreduce(&sendbuf, &recvbuf, 1, MPIU_INT, MPI_MAX, PetscObjectComm((PetscObject)ksp)));
1572:     if (recvbuf) {
1573:       *reason = KSP_DIVERGED_PC_FAILED;
1574:       PetscCall(PCSetFailedReason(ksp->pc, (PCFailedReason)recvbuf));
1575:       PetscCall(PetscInfo(ksp, "Linear solver pcsetup fails, declaring divergence \n"));
1576:     } else {
1577:       *reason = KSP_DIVERGED_NANORINF;
1578:       PetscCall(PetscInfo(ksp, "Linear solver has created a not a number (NaN) as the residual norm, declaring divergence \n"));
1579:     }
1580:   } else if (rnorm <= ksp->ttol) {
1581:     if (rnorm < ksp->abstol) {
1582:       PetscCall(PetscInfo(ksp, "Linear solver has converged. Residual norm %14.12e is less than absolute tolerance %14.12e at iteration %" PetscInt_FMT "\n", (double)rnorm, (double)ksp->abstol, n));
1583:       *reason = KSP_CONVERGED_ATOL;
1584:     } else {
1585:       if (cctx->initialrtol) {
1586:         PetscCall(PetscInfo(ksp, "Linear solver has converged. Residual norm %14.12e is less than relative tolerance %14.12e times initial residual norm %14.12e at iteration %" PetscInt_FMT "\n", (double)rnorm, (double)ksp->rtol, (double)ksp->rnorm0, n));
1587:       } else {
1588:         PetscCall(PetscInfo(ksp, "Linear solver has converged. Residual norm %14.12e is less than relative tolerance %14.12e times initial right hand side norm %14.12e at iteration %" PetscInt_FMT "\n", (double)rnorm, (double)ksp->rtol, (double)ksp->rnorm0, n));
1589:       }
1590:       *reason = KSP_CONVERGED_RTOL;
1591:     }
1592:   } else if (rnorm >= ksp->divtol * ksp->rnorm0) {
1593:     PetscCall(PetscInfo(ksp, "Linear solver is diverging. Initial right hand size norm %14.12e, current residual norm %14.12e at iteration %" PetscInt_FMT "\n", (double)ksp->rnorm0, (double)rnorm, n));
1594:     *reason = KSP_DIVERGED_DTOL;
1595:   }
1596:   PetscFunctionReturn(PETSC_SUCCESS);
1597: }

1599: /*@C
1600:    KSPConvergedDefaultDestroy - Frees the space used by the `KSPConvergedDefault()` function context

1602:    Not Collective

1604:    Input Parameter:
1605: .  ctx - convergence context

1607:    Level: intermediate

1609:    Note:
1610:    Pass this function name into `KSPSetConvergenceTest()` along with the context obtained with `KSPConvergedDefaultCreate()` and `KSPConvergedDefault()`

1612: .seealso: [](chapter_ksp), `KSP`, `KSPConvergedDefault()`, `KSPConvergedDefaultCreate()`, `KSPSetConvergenceTest()`, `KSPSetTolerances()`, `KSPConvergedSkip()`,
1613:           `KSPConvergedReason`, `KSPGetConvergedReason()`, `KSPConvergedDefaultSetUIRNorm()`, `KSPConvergedDefaultSetUMIRNorm()`
1614: @*/
1615: PetscErrorCode KSPConvergedDefaultDestroy(void *ctx)
1616: {
1617:   KSPConvergedDefaultCtx *cctx = (KSPConvergedDefaultCtx *)ctx;

1619:   PetscFunctionBegin;
1620:   PetscCall(VecDestroy(&cctx->work));
1621:   PetscCall(PetscFree(ctx));
1622:   PetscFunctionReturn(PETSC_SUCCESS);
1623: }

1625: /*
1626:    KSPBuildSolutionDefault - Default code to create/move the solution.

1628:    Collective

1630:    Input Parameters:
1631: +  ksp - iterative context
1632: -  v   - pointer to the user's vector

1634:    Output Parameter:
1635: .  V - pointer to a vector containing the solution

1637:    Level: advanced

1639:    Developers Note:
1640:    This is PETSC_EXTERN because it may be used by user written plugin `KSPType` implementations

1642: .seealso: [](chapter_ksp), `KSP`, `KSPGetSolution()`, `KSPBuildResidualDefault()`
1643: */
1644: PetscErrorCode KSPBuildSolutionDefault(KSP ksp, Vec v, Vec *V)
1645: {
1646:   PetscFunctionBegin;
1647:   if (ksp->pc_side == PC_RIGHT) {
1648:     if (ksp->pc) {
1649:       PetscCheck(v, PetscObjectComm((PetscObject)ksp), PETSC_ERR_SUP, "Not working with right preconditioner");
1650:       PetscCall(KSP_PCApply(ksp, ksp->vec_sol, v));
1651:       *V = v;
1652:     } else {
1653:       if (v) {
1654:         PetscCall(VecCopy(ksp->vec_sol, v));
1655:         *V = v;
1656:       } else *V = ksp->vec_sol;
1657:     }
1658:   } else if (ksp->pc_side == PC_SYMMETRIC) {
1659:     if (ksp->pc) {
1660:       PetscCheck(!ksp->transpose_solve, PetscObjectComm((PetscObject)ksp), PETSC_ERR_SUP, "Not working with symmetric preconditioner and transpose solve");
1661:       PetscCheck(v, PetscObjectComm((PetscObject)ksp), PETSC_ERR_SUP, "Not working with symmetric preconditioner");
1662:       PetscCall(PCApplySymmetricRight(ksp->pc, ksp->vec_sol, v));
1663:       *V = v;
1664:     } else {
1665:       if (v) {
1666:         PetscCall(VecCopy(ksp->vec_sol, v));
1667:         *V = v;
1668:       } else *V = ksp->vec_sol;
1669:     }
1670:   } else {
1671:     if (v) {
1672:       PetscCall(VecCopy(ksp->vec_sol, v));
1673:       *V = v;
1674:     } else *V = ksp->vec_sol;
1675:   }
1676:   PetscFunctionReturn(PETSC_SUCCESS);
1677: }

1679: /*
1680:    KSPBuildResidualDefault - Default code to compute the residual.

1682:    Collecive on ksp

1684:    Input Parameters:
1685: .  ksp - iterative context
1686: .  t   - pointer to temporary vector
1687: .  v   - pointer to user vector

1689:    Output Parameter:
1690: .  V - pointer to a vector containing the residual

1692:    Level: advanced

1694:    Developers Note:
1695:    This is PETSC_EXTERN because it may be used by user written plugin `KSPType` implementations

1697: .seealso: [](chapter_ksp), `KSP`, `KSPBuildSolutionDefault()`
1698: */
1699: PetscErrorCode KSPBuildResidualDefault(KSP ksp, Vec t, Vec v, Vec *V)
1700: {
1701:   Mat Amat, Pmat;

1703:   PetscFunctionBegin;
1704:   if (!ksp->pc) PetscCall(KSPGetPC(ksp, &ksp->pc));
1705:   PetscCall(PCGetOperators(ksp->pc, &Amat, &Pmat));
1706:   PetscCall(KSPBuildSolution(ksp, t, NULL));
1707:   PetscCall(KSP_MatMult(ksp, Amat, t, v));
1708:   PetscCall(VecAYPX(v, -1.0, ksp->vec_rhs));
1709:   *V = v;
1710:   PetscFunctionReturn(PETSC_SUCCESS);
1711: }

1713: /*@C
1714:   KSPCreateVecs - Gets a number of work vectors suitably sized for the operator in the `KSP`

1716:   Collective

1718:   Input Parameters:
1719: + ksp  - iterative context
1720: . rightn  - number of right work vectors
1721: - leftn   - number of left work vectors to allocate

1723:   Output Parameters:
1724: +  right - the array of vectors created
1725: -  left - the array of left vectors

1727:    Level: advanced

1729:    Notes:
1730:    The right vector has as many elements as the matrix has columns. The left
1731:      vector has as many elements as the matrix has rows.

1733:    The vectors are new vectors that are not owned by the `KSP`, they should be destroyed with calls to `VecDestroyVecs()` when no longer needed.

1735:    Developers Note:
1736:    First tries to duplicate the rhs and solution vectors of the `KSP`, if they do not exist tries to get them from the matrix, if
1737:    that does not exist tries to get them from the `DM` (if it is provided).

1739: .seealso: [](chapter_ksp), `MatCreateVecs()`, `VecDestroyVecs()`, `KSPSetWorkVecs()`
1740: @*/
1741: PetscErrorCode KSPCreateVecs(KSP ksp, PetscInt rightn, Vec **right, PetscInt leftn, Vec **left)
1742: {
1743:   Vec       vecr = NULL, vecl = NULL;
1744:   PetscBool matset, pmatset, isshell, preferdm = PETSC_FALSE;
1745:   Mat       mat = NULL;

1747:   PetscFunctionBegin;
1748:   if (ksp->dm) {
1749:     PetscCall(PetscObjectTypeCompare((PetscObject)ksp->dm, DMSHELL, &isshell));
1750:     preferdm = isshell ? PETSC_FALSE : PETSC_TRUE;
1751:   }
1752:   if (rightn) {
1753:     PetscCheck(right, PetscObjectComm((PetscObject)ksp), PETSC_ERR_ARG_INCOMP, "You asked for right vectors but did not pass a pointer to hold them");
1754:     if (ksp->vec_sol) vecr = ksp->vec_sol;
1755:     else {
1756:       if (preferdm) {
1757:         PetscCall(DMGetGlobalVector(ksp->dm, &vecr));
1758:       } else if (ksp->pc) {
1759:         PetscCall(PCGetOperatorsSet(ksp->pc, &matset, &pmatset));
1760:         /* check for mat before pmat because for KSPLSQR pmat may be a different size than mat since pmat maybe mat'*mat */
1761:         if (matset) {
1762:           PetscCall(PCGetOperators(ksp->pc, &mat, NULL));
1763:           PetscCall(MatCreateVecs(mat, &vecr, NULL));
1764:         } else if (pmatset) {
1765:           PetscCall(PCGetOperators(ksp->pc, NULL, &mat));
1766:           PetscCall(MatCreateVecs(mat, &vecr, NULL));
1767:         }
1768:       }
1769:       if (!vecr && ksp->dm) PetscCall(DMGetGlobalVector(ksp->dm, &vecr));
1770:       PetscCheck(vecr, PetscObjectComm((PetscObject)ksp), PETSC_ERR_ARG_WRONGSTATE, "You requested a vector from a KSP that cannot provide one");
1771:     }
1772:     PetscCall(VecDuplicateVecs(vecr, rightn, right));
1773:     if (!ksp->vec_sol) {
1774:       if (preferdm) {
1775:         PetscCall(DMRestoreGlobalVector(ksp->dm, &vecr));
1776:       } else if (mat) {
1777:         PetscCall(VecDestroy(&vecr));
1778:       } else if (ksp->dm) {
1779:         PetscCall(DMRestoreGlobalVector(ksp->dm, &vecr));
1780:       }
1781:     }
1782:   }
1783:   if (leftn) {
1784:     PetscCheck(left, PetscObjectComm((PetscObject)ksp), PETSC_ERR_ARG_INCOMP, "You asked for left vectors but did not pass a pointer to hold them");
1785:     if (ksp->vec_rhs) vecl = ksp->vec_rhs;
1786:     else {
1787:       if (preferdm) {
1788:         PetscCall(DMGetGlobalVector(ksp->dm, &vecl));
1789:       } else if (ksp->pc) {
1790:         PetscCall(PCGetOperatorsSet(ksp->pc, &matset, &pmatset));
1791:         /* check for mat before pmat because for KSPLSQR pmat may be a different size than mat since pmat maybe mat'*mat */
1792:         if (matset) {
1793:           PetscCall(PCGetOperators(ksp->pc, &mat, NULL));
1794:           PetscCall(MatCreateVecs(mat, NULL, &vecl));
1795:         } else if (pmatset) {
1796:           PetscCall(PCGetOperators(ksp->pc, NULL, &mat));
1797:           PetscCall(MatCreateVecs(mat, NULL, &vecl));
1798:         }
1799:       }
1800:       if (!vecl && ksp->dm) PetscCall(DMGetGlobalVector(ksp->dm, &vecl));
1801:       PetscCheck(vecl, PetscObjectComm((PetscObject)ksp), PETSC_ERR_ARG_WRONGSTATE, "You requested a vector from a KSP that cannot provide one");
1802:     }
1803:     PetscCall(VecDuplicateVecs(vecl, leftn, left));
1804:     if (!ksp->vec_rhs) {
1805:       if (preferdm) {
1806:         PetscCall(DMRestoreGlobalVector(ksp->dm, &vecl));
1807:       } else if (mat) {
1808:         PetscCall(VecDestroy(&vecl));
1809:       } else if (ksp->dm) {
1810:         PetscCall(DMRestoreGlobalVector(ksp->dm, &vecl));
1811:       }
1812:     }
1813:   }
1814:   PetscFunctionReturn(PETSC_SUCCESS);
1815: }

1817: /*@C
1818:   KSPSetWorkVecs - Sets a number of work vectors into a `KSP` object

1820:   Collective

1822:   Input Parameters:
1823: + ksp  - iterative context
1824: - nw   - number of work vectors to allocate

1826:   Level: developer

1828:   Developers Note:
1829:   This is PETSC_EXTERN because it may be used by user written plugin `KSPType` implementations

1831: .seealso: [](chapter_ksp), `KSP`, `KSPCreateVecs()`
1832: @*/
1833: PetscErrorCode KSPSetWorkVecs(KSP ksp, PetscInt nw)
1834: {
1835:   PetscFunctionBegin;
1836:   PetscCall(VecDestroyVecs(ksp->nwork, &ksp->work));
1837:   ksp->nwork = nw;
1838:   PetscCall(KSPCreateVecs(ksp, nw, &ksp->work, 0, NULL));
1839:   PetscFunctionReturn(PETSC_SUCCESS);
1840: }

1842: /*
1843:   KSPDestroyDefault - Destroys a iterative context variable for methods with no separate context.  Preferred calling sequence `KSPDestroy()`.

1845:   Input Parameter:
1846: . ksp - the iterative context

1848:    Developers Note:
1849:    This is PETSC_EXTERN because it may be used by user written plugin `KSPType` implementations

1851: */
1852: PetscErrorCode KSPDestroyDefault(KSP ksp)
1853: {
1854:   PetscFunctionBegin;
1856:   PetscCall(PetscFree(ksp->data));
1857:   PetscFunctionReturn(PETSC_SUCCESS);
1858: }

1860: /*@
1861:    KSPGetConvergedReason - Gets the reason the `KSP` iteration was stopped.

1863:    Not Collective

1865:    Input Parameter:
1866: .  ksp - the `KSP` context

1868:    Output Parameter:
1869: .  reason - negative value indicates diverged, positive value converged, see `KSPConvergedReason` for the possible values

1871:    Options Database Key:
1872: .   -ksp_converged_reason - prints the reason to standard out

1874:    Level: intermediate

1876:    Notes:
1877:     If this routine is called before or doing the `KSPSolve()` the value of `KSP_CONVERGED_ITERATING` is returned

1879: .seealso: [](chapter_ksp), `KSPConvergedReason`, `KSP`, `KSPSetConvergenceTest()`, `KSPConvergedDefault()`, `KSPSetTolerances()`, `KSPConvergedReason`,
1880:           `KSPConvergedReasonView()`
1881: @*/
1882: PetscErrorCode KSPGetConvergedReason(KSP ksp, KSPConvergedReason *reason)
1883: {
1884:   PetscFunctionBegin;
1887:   *reason = ksp->reason;
1888:   PetscFunctionReturn(PETSC_SUCCESS);
1889: }

1891: /*@C
1892:    KSPGetConvergedReasonString - Return a human readable string for a `KSPConvergedReason`

1894:    Not Collective

1896:    Input Parameter:
1897: .  ksp - the `KSP` context

1899:    Output Parameter:
1900: .  strreason - a human readable string that describes ksp converged reason

1902:    Level: beginner

1904: .seealso: [](chapter_ksp), `KSP`, `KSPGetConvergedReason()`
1905: @*/
1906: PetscErrorCode KSPGetConvergedReasonString(KSP ksp, const char **strreason)
1907: {
1908:   PetscFunctionBegin;
1911:   *strreason = KSPConvergedReasons[ksp->reason];
1912:   PetscFunctionReturn(PETSC_SUCCESS);
1913: }

1915: #include <petsc/private/dmimpl.h>
1916: /*@
1917:    KSPSetDM - Sets the `DM` that may be used by some preconditioners

1919:    Logically Collective

1921:    Input Parameters:
1922: +  ksp - the `KSP`
1923: -  dm - the `DM`, cannot be `NULL` to remove a previously set `DM`

1925:    Level: intermediate

1927:    Notes:
1928:    If this is used then the `KSP` will attempt to use the `DM` to create the matrix and use the routine set with
1929:    `DMKSPSetComputeOperators()`. Use `KSPSetDMActive`(ksp,`PETSC_FALSE`) to instead use the matrix you've provided with
1930:    `KSPSetOperators()`.

1932:    A `DM` can only be used for solving one problem at a time because information about the problem is stored on the `DM`,
1933:    even when not using interfaces like `DMKSPSetComputeOperators()`.  Use `DMClone()` to get a distinct `DM` when solving
1934:    different problems using the same function space.

1936: .seealso: [](chapter_ksp), `KSP`, `DM`, `KSPGetDM()`, `KSPSetDMActive()`, `KSPSetComputeOperators()`, `KSPSetComputeRHS()`, `KSPSetComputeInitialGuess()`, `DMKSPSetComputeOperators()`, `DMKSPSetComputeRHS()`, `DMKSPSetComputeInitialGuess()`
1937: @*/
1938: PetscErrorCode KSPSetDM(KSP ksp, DM dm)
1939: {
1940:   PC pc;

1942:   PetscFunctionBegin;
1945:   PetscCall(PetscObjectReference((PetscObject)dm));
1946:   if (ksp->dm) { /* Move the DMSNES context over to the new DM unless the new DM already has one */
1947:     if (ksp->dm->dmksp && !dm->dmksp) {
1948:       DMKSP kdm;
1949:       PetscCall(DMCopyDMKSP(ksp->dm, dm));
1950:       PetscCall(DMGetDMKSP(ksp->dm, &kdm));
1951:       if (kdm->originaldm == ksp->dm) kdm->originaldm = dm; /* Grant write privileges to the replacement DM */
1952:     }
1953:     PetscCall(DMDestroy(&ksp->dm));
1954:   }
1955:   ksp->dm     = dm;
1956:   ksp->dmAuto = PETSC_FALSE;
1957:   PetscCall(KSPGetPC(ksp, &pc));
1958:   PetscCall(PCSetDM(pc, dm));
1959:   ksp->dmActive = PETSC_TRUE;
1960:   PetscFunctionReturn(PETSC_SUCCESS);
1961: }

1963: /*@
1964:    KSPSetDMActive - Indicates the `DM` should be used to generate the linear system matrix and right hand side vector

1966:    Logically Collective

1968:    Input Parameters:
1969: +  ksp - the `KSP`
1970: -  flg - use the `DM`

1972:    Level: intermediate

1974:    Note:
1975:    By default `KSPSetDM()` sets the `DM` as active, call `KSPSetDMActive`(ksp,`PETSC_FALSE`); after `KSPSetDM`(ksp,dm) to not have the `KSP` object use the `DM` to generate the matrices.

1977: .seealso: [](chapter_ksp), `KSP`, `DM`, `KSPGetDM()`, `KSPSetDM()`, `SNESSetDM()`, `KSPSetComputeOperators()`, `KSPSetComputeRHS()`, `KSPSetComputeInitialGuess()`
1978: @*/
1979: PetscErrorCode KSPSetDMActive(KSP ksp, PetscBool flg)
1980: {
1981:   PetscFunctionBegin;
1984:   ksp->dmActive = flg;
1985:   PetscFunctionReturn(PETSC_SUCCESS);
1986: }

1988: /*@
1989:    KSPGetDM - Gets the `DM` that may be used by some preconditioners

1991:    Not Collective

1993:    Input Parameter:
1994: . ksp - the `KSP`

1996:    Output Parameter:
1997: .  dm - the `DM`

1999:    Level: intermediate

2001: .seealso: [](chapter_ksp), `KSP`, `DM`, `KSPSetDM()`, `KSPSetDMActive()`
2002: @*/
2003: PetscErrorCode KSPGetDM(KSP ksp, DM *dm)
2004: {
2005:   PetscFunctionBegin;
2007:   if (!ksp->dm) {
2008:     PetscCall(DMShellCreate(PetscObjectComm((PetscObject)ksp), &ksp->dm));
2009:     ksp->dmAuto = PETSC_TRUE;
2010:   }
2011:   *dm = ksp->dm;
2012:   PetscFunctionReturn(PETSC_SUCCESS);
2013: }

2015: /*@
2016:    KSPSetApplicationContext - Sets the optional user-defined context for the linear solver.

2018:    Logically Collective

2020:    Input Parameters:
2021: +  ksp - the `KSP` context
2022: -  usrP - optional user context

2024:    Level: intermediate

2026:    Notes:
2027:    The user context is a way for users to attach any information to the `KSP` that they may need later when interacting with the `KSP`

2029:    Use `KSPGetApplicationContext()` to get access to the context at a later time.

2031:    Fortran Note:
2032:    To use this from Fortran you must write a Fortran interface definition for this
2033:    function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

2035: .seealso: [](chapter_ksp), `KSP`, `KSPGetApplicationContext()`
2036: @*/
2037: PetscErrorCode KSPSetApplicationContext(KSP ksp, void *usrP)
2038: {
2039:   PC pc;

2041:   PetscFunctionBegin;
2043:   ksp->user = usrP;
2044:   PetscCall(KSPGetPC(ksp, &pc));
2045:   PetscCall(PCSetApplicationContext(pc, usrP));
2046:   PetscFunctionReturn(PETSC_SUCCESS);
2047: }

2049: /*@
2050:    KSPGetApplicationContext - Gets the user-defined context for the linear solver set with `KSPSetApplicationContext()`

2052:    Not Collective

2054:    Input Parameter:
2055: .  ksp - `KSP` context

2057:    Output Parameter:
2058: .  usrP - user context

2060:    Level: intermediate

2062:    Fortran Notes:
2063:    To use this from Fortran you must write a Fortran interface definition for this
2064:    function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

2066: .seealso: [](chapter_ksp), `KSP`, `KSPSetApplicationContext()`
2067: @*/
2068: PetscErrorCode KSPGetApplicationContext(KSP ksp, void *usrP)
2069: {
2070:   PetscFunctionBegin;
2072:   *(void **)usrP = ksp->user;
2073:   PetscFunctionReturn(PETSC_SUCCESS);
2074: }

2076: #include <petsc/private/pcimpl.h>

2078: /*@
2079:    KSPCheckSolve - Checks if the `PCSetUp()` or `KSPSolve()` failed and set the error flag for the outer `PC`. A `KSP_DIVERGED_ITS` is
2080:          not considered a failure in this context

2082:    Collective

2084:    Input Parameters:
2085: +  ksp - the linear solver `KSP` context.
2086: .  pc - the preconditioner context
2087: -  vec - a vector that will be initialized with Inf to indicate lack of convergence

2089:    Level: developer

2091:    Note:
2092:    This is called within `KSPSolve()` and `PCApply()` to check if an error has been detected on any particular MPI ranks. By initializing the vector
2093:    with Inf the next call to `KSPCheckNorm()` or `KSPCheckDot()` will provide the same information to all the MPI ranks that an error occurred on
2094:    at least one of the ranks.

2096:    This may be called by a subset of the processes in the `PC`.

2098:    Developer Note:
2099:    This is used to manage returning with appropriate information from preconditioners whose inner `KSP` solvers have failed in some way

2101: .seealso: [](chapter_ksp), `KSP`, `KSPCreate()`, `KSPSetType()`, `KSP`, `KSPCheckNorm()`, `KSPCheckDot()`
2102: @*/
2103: PetscErrorCode KSPCheckSolve(KSP ksp, PC pc, Vec vec)
2104: {
2105:   PCFailedReason pcreason;
2106:   PC             subpc;

2108:   PetscFunctionBegin;
2109:   PetscCall(KSPGetPC(ksp, &subpc));
2110:   PetscCall(PCGetFailedReason(subpc, &pcreason));
2111:   if (pcreason || (ksp->reason < 0 && ksp->reason != KSP_DIVERGED_ITS)) {
2112:     PetscCheck(!pc->erroriffailure, PETSC_COMM_SELF, PETSC_ERR_NOT_CONVERGED, "Detected not converged in KSP inner solve: KSP reason %s PC reason %s", KSPConvergedReasons[ksp->reason], PCFailedReasons[pcreason]);
2113:     PetscCall(PetscInfo(ksp, "Detected not converged in KSP inner solve: KSP reason %s PC reason %s\n", KSPConvergedReasons[ksp->reason], PCFailedReasons[pcreason]));
2114:     pc->failedreason = PC_SUBPC_ERROR;
2115:     if (vec) PetscCall(VecSetInf(vec));
2116:   }
2117:   PetscFunctionReturn(PETSC_SUCCESS);
2118: }