Actual source code: convest.c

petsc-master 2020-08-10
Report Typos and Errors
  1:  #include <petscconvest.h>
  2:  #include <petscdmplex.h>
  3:  #include <petscds.h>

  5:  #include <petsc/private/petscconvestimpl.h>

  7: static PetscErrorCode zero_private(PetscInt dim, PetscReal time, const PetscReal x[], PetscInt Nc, PetscScalar *u, void *ctx)
  8: {
  9:   PetscInt c;
 10:   for (c = 0; c < Nc; ++c) u[c] = 0.0;
 11:   return 0;
 12: }

 14: /*@
 15:   PetscConvEstDestroy - Destroys a PetscConvEst object

 17:   Collective on PetscConvEst

 19:   Input Parameter:
 20: . ce - The PetscConvEst object

 22:   Level: beginner

 24: .seealso: PetscConvEstCreate(), PetscConvEstGetConvRate()
 25: @*/
 26: PetscErrorCode PetscConvEstDestroy(PetscConvEst *ce)
 27: {

 31:   if (!*ce) return(0);
 33:   if (--((PetscObject)(*ce))->refct > 0) {
 34:     *ce = NULL;
 35:     return(0);
 36:   }
 37:   PetscFree3((*ce)->initGuess, (*ce)->exactSol, (*ce)->ctxs);
 38:   PetscFree((*ce)->errors);
 39:   PetscHeaderDestroy(ce);
 40:   return(0);
 41: }

 43: /*@
 44:   PetscConvEstSetFromOptions - Sets a PetscConvEst object from options

 46:   Collective on PetscConvEst

 48:   Input Parameters:
 49: . ce - The PetscConvEst object

 51:   Level: beginner

 53: .seealso: PetscConvEstCreate(), PetscConvEstGetConvRate()
 54: @*/
 55: PetscErrorCode PetscConvEstSetFromOptions(PetscConvEst ce)
 56: {

 60:   PetscOptionsBegin(PetscObjectComm((PetscObject) ce), "", "Convergence Estimator Options", "PetscConvEst");
 61:   PetscOptionsInt("-convest_num_refine", "The number of refinements for the convergence check", "PetscConvEst", ce->Nr, &ce->Nr, NULL);
 62:   PetscOptionsReal("-convest_refine_factor", "The increase in resolution in each dimension", "PetscConvEst", ce->r, &ce->r, NULL);
 63:   PetscOptionsBool("-convest_monitor", "Monitor the error for each convergence check", "PetscConvEst", ce->monitor, &ce->monitor, NULL);
 64:   PetscOptionsEnd();
 65:   return(0);
 66: }

 68: /*@
 69:   PetscConvEstView - Views a PetscConvEst object

 71:   Collective on PetscConvEst

 73:   Input Parameters:
 74: + ce     - The PetscConvEst object
 75: - viewer - The PetscViewer object

 77:   Level: beginner

 79: .seealso: PetscConvEstCreate(), PetscConvEstGetConvRate()
 80: @*/
 81: PetscErrorCode PetscConvEstView(PetscConvEst ce, PetscViewer viewer)
 82: {

 86:   PetscObjectPrintClassNamePrefixType((PetscObject) ce, viewer);
 87:   PetscViewerASCIIPrintf(viewer, "ConvEst with %D levels\n", ce->Nr+1);
 88:   return(0);
 89: }

 91: /*@
 92:   PetscConvEstGetSolver - Gets the solver used to produce discrete solutions

 94:   Not collective

 96:   Input Parameter:
 97: . ce     - The PetscConvEst object

 99:   Output Parameter:
100: . solver - The solver

102:   Level: intermediate

104: .seealso: PetscConvEstSetSolver(), PetscConvEstCreate(), PetscConvEstGetConvRate()
105: @*/
106: PetscErrorCode PetscConvEstGetSolver(PetscConvEst ce, PetscObject *solver)
107: {
111:   *solver = ce->solver;
112:   return(0);
113: }

115: /*@
116:   PetscConvEstSetSolver - Sets the solver used to produce discrete solutions

118:   Not collective

120:   Input Parameters:
121: + ce     - The PetscConvEst object
122: - solver - The solver

124:   Level: intermediate

126:   Note: The solver MUST have an attached DM/DS, so that we know the exact solution

128: .seealso: PetscConvEstGetSNES(), PetscConvEstCreate(), PetscConvEstGetConvRate()
129: @*/
130: PetscErrorCode PetscConvEstSetSolver(PetscConvEst ce, PetscObject solver)
131: {

137:   ce->solver = solver;
138:   (*ce->ops->setsolver)(ce, solver);
139:   return(0);
140: }

142: /*@
143:   PetscConvEstSetUp - After the solver is specified, we create structures for estimating convergence

145:   Collective on PetscConvEst

147:   Input Parameters:
148: . ce - The PetscConvEst object

150:   Level: beginner

152: .seealso: PetscConvEstCreate(), PetscConvEstGetConvRate()
153: @*/
154: PetscErrorCode PetscConvEstSetUp(PetscConvEst ce)
155: {
156:   PetscInt       Nf, f, Nds, s;

160:   DMGetNumFields(ce->idm, &Nf);
161:   ce->Nf = PetscMax(Nf, 1);
162:   PetscMalloc1((ce->Nr+1)*ce->Nf, &ce->errors);
163:   PetscCalloc3(ce->Nf, &ce->initGuess, ce->Nf, &ce->exactSol, ce->Nf, &ce->ctxs);
164:   for (f = 0; f < Nf; ++f) ce->initGuess[f] = zero_private;
165:   DMGetNumDS(ce->idm, &Nds);
166:   for (s = 0; s < Nds; ++s) {
167:     PetscDS         ds;
168:     DMLabel         label;
169:     IS              fieldIS;
170:     const PetscInt *fields;
171:     PetscInt        dsNf;

173:     DMGetRegionNumDS(ce->idm, s, &label, &fieldIS, &ds);
174:     PetscDSGetNumFields(ds, &dsNf);
175:     if (fieldIS) {ISGetIndices(fieldIS, &fields);}
176:     for (f = 0; f < dsNf; ++f) {
177:       const PetscInt field = fields[f];
178:       PetscDSGetExactSolution(ds, field, &ce->exactSol[field], &ce->ctxs[field]);
179:     }
180:     if (fieldIS) {ISRestoreIndices(fieldIS, &fields);}
181:   }
182:   for (f = 0; f < Nf; ++f) {
183:     if (!ce->exactSol[f]) SETERRQ1(PetscObjectComm((PetscObject) ce), PETSC_ERR_ARG_WRONG, "DS must contain exact solution functions in order to estimate convergence, missing for field %D", f);
184:   }
185:   return(0);
186: }

188: PetscErrorCode PetscConvEstComputeInitialGuess(PetscConvEst ce, PetscInt r, DM dm, Vec u)
189: {

196:   (*ce->ops->initguess)(ce, r, dm, u);
197:   return(0);
198: }

200: PetscErrorCode PetscConvEstComputeError(PetscConvEst ce, PetscInt r, DM dm, Vec u, PetscReal errors[])
201: {

209:   (*ce->ops->computeerror)(ce, r, dm, u, errors);
210:   return(0);
211: }

213: /*@
214:   PetscConvEstMonitorDefault - Monitors the convergence estimation loop

216:   Collective on PetscConvEst

218:   Input Parameter:
219: + ce - The PetscConvEst object
220: - r  - The refinement level

222:   Options database keys:
223: + -convest_monitor - Activate the monitor

225:   Level: intermediate

227: .seealso: PetscConvEstCreate(), PetscConvEstGetConvRate(), SNESSolve(), TSSolve()
228: @*/
229: PetscErrorCode PetscConvEstMonitorDefault(PetscConvEst ce, PetscInt r)
230: {
231:   MPI_Comm       comm;
232:   PetscInt       f;

236:   if (ce->monitor) {
237:     PetscReal *errors = &ce->errors[r*ce->Nf];

239:     PetscObjectGetComm((PetscObject) ce, &comm);
240:     PetscPrintf(comm, "L_2 Error: ");
241:     if (ce->Nf > 1) {PetscPrintf(comm, "[");}
242:     for (f = 0; f < ce->Nf; ++f) {
243:       if (f > 0) {PetscPrintf(comm, ", ");}
244:       if (errors[f] < 1.0e-11) {PetscPrintf(comm, "< 1e-11");}
245:       else                     {PetscPrintf(comm, "%g", (double) errors[f]);}
246:     }
247:     if (ce->Nf > 1) {PetscPrintf(comm, "]");}
248:     PetscPrintf(comm, "\n");
249:   }
250:   return(0);
251: }

253: static PetscErrorCode PetscConvEstSetSNES_Private(PetscConvEst ce, PetscObject solver)
254: {
255:   PetscClassId   id;

259:   PetscObjectGetClassId(ce->solver, &id);
260:   if (id != SNES_CLASSID) SETERRQ(PetscObjectComm((PetscObject) ce), PETSC_ERR_ARG_WRONG, "Solver was not a SNES");
261:   SNESGetDM((SNES) ce->solver, &ce->idm);
262:   return(0);
263: }

265: static PetscErrorCode PetscConvEstInitGuessSNES_Private(PetscConvEst ce, PetscInt r, DM dm, Vec u)
266: {

270:   DMProjectFunction(dm, 0.0, ce->initGuess, ce->ctxs, INSERT_VALUES, u);
271:   return(0);
272: }

274: static PetscErrorCode PetscConvEstComputeErrorSNES_Private(PetscConvEst ce, PetscInt r, DM dm, Vec u, PetscReal errors[])
275: {

279:   DMComputeL2FieldDiff(dm, 0.0, ce->exactSol, ce->ctxs, u, errors);
280:   return(0);
281: }

283: static PetscErrorCode PetscConvEstGetConvRateSNES_Private(PetscConvEst ce, PetscReal alpha[])
284: {
285:   SNES           snes = (SNES) ce->solver;
286:   DM            *dm;
287:   PetscObject    disc;
288:   PetscReal     *x, *y, slope, intercept;
289:   PetscInt      *dof, Nr = ce->Nr, r, f, dim, oldlevel, oldnlev;
290:   void          *ctx;

294:   if (ce->r != 2.0) SETERRQ1(PetscObjectComm((PetscObject) ce), PETSC_ERR_SUP, "Only refinement factor 2 is currently supported (not %g)", (double) ce->r);
295:   DMGetDimension(ce->idm, &dim);
296:   DMGetApplicationContext(ce->idm, &ctx);
297:   DMPlexSetRefinementUniform(ce->idm, PETSC_TRUE);
298:   DMGetRefineLevel(ce->idm, &oldlevel);
299:   PetscMalloc2((Nr+1), &dm, (Nr+1)*ce->Nf, &dof);
300:   /* Loop over meshes */
301:   dm[0] = ce->idm;
302:   for (r = 0; r <= Nr; ++r) {
303:     Vec           u;
304: #if defined(PETSC_USE_LOG)
305:     PetscLogStage stage;
306: #endif
307:     char          stageName[PETSC_MAX_PATH_LEN];
308:     const char   *dmname, *uname;

310:     PetscSNPrintf(stageName, PETSC_MAX_PATH_LEN-1, "ConvEst Refinement Level %D", r);
311:     PetscLogStageRegister(stageName, &stage);
312:     PetscLogStagePush(stage);
313:     if (r > 0) {
314:       DMRefine(dm[r-1], MPI_COMM_NULL, &dm[r]);
315:       DMSetCoarseDM(dm[r], dm[r-1]);
316:       DMCopyTransform(ce->idm, dm[r]);
317:       PetscObjectGetName((PetscObject) dm[r-1], &dmname);
318:       PetscObjectSetName((PetscObject) dm[r], dmname);
319:       for (f = 0; f <= ce->Nf; ++f) {
320:         PetscErrorCode (*nspconstr)(DM, PetscInt, MatNullSpace *);

322:         DMGetNullSpaceConstructor(dm[r-1], f, &nspconstr);
323:         DMSetNullSpaceConstructor(dm[r],   f,  nspconstr);
324:       }
325:     }
326:     DMViewFromOptions(dm[r], NULL, "-conv_dm_view");
327:     /* Create solution */
328:     DMCreateGlobalVector(dm[r], &u);
329:     DMGetField(dm[r], 0, NULL, &disc);
330:     PetscObjectGetName(disc, &uname);
331:     PetscObjectSetName((PetscObject) u, uname);
332:     /* Setup solver */
333:     SNESReset(snes);
334:     SNESSetDM(snes, dm[r]);
335:     DMPlexSetSNESLocalFEM(dm[r], ctx, ctx, ctx);
336:     SNESSetFromOptions(snes);
337:     /* Create initial guess */
338:     PetscConvEstComputeInitialGuess(ce, r, dm[r], u);
339:     SNESSolve(snes, NULL, u);
340:     PetscLogEventBegin(ce->event, ce, 0, 0, 0);
341:     PetscConvEstComputeError(ce, r, dm[r], u, &ce->errors[r*ce->Nf]);
342:     PetscLogEventEnd(ce->event, ce, 0, 0, 0);
343:     for (f = 0; f < ce->Nf; ++f) {
344:       PetscSection s, fs;
345:       PetscInt     lsize;

347:       /* Could use DMGetOutputDM() to add in Dirichlet dofs */
348:       DMGetLocalSection(dm[r], &s);
349:       PetscSectionGetField(s, f, &fs);
350:       PetscSectionGetConstrainedStorageSize(fs, &lsize);
351:       MPI_Allreduce(&lsize, &dof[r*ce->Nf+f], 1, MPIU_INT, MPI_SUM, PetscObjectComm((PetscObject) snes));
352:       PetscLogEventSetDof(ce->event, f, dof[r*ce->Nf+f]);
353:       PetscLogEventSetError(ce->event, f, ce->errors[r*ce->Nf+f]);
354:     }
355:     /* Monitor */
356:     PetscConvEstMonitorDefault(ce, r);
357:     if (!r) {
358:       /* PCReset() does not wipe out the level structure */
359:       KSP ksp;
360:       PC  pc;

362:       SNESGetKSP(snes, &ksp);
363:       KSPGetPC(ksp, &pc);
364:       PCMGGetLevels(pc, &oldnlev);
365:     }
366:     /* Cleanup */
367:     VecDestroy(&u);
368:     PetscLogStagePop();
369:   }
370:   for (r = 1; r <= Nr; ++r) {
371:     DMDestroy(&dm[r]);
372:   }
373:   /* Fit convergence rate */
374:   PetscMalloc2(Nr+1, &x, Nr+1, &y);
375:   for (f = 0; f < ce->Nf; ++f) {
376:     for (r = 0; r <= Nr; ++r) {
377:       x[r] = PetscLog10Real(dof[r*ce->Nf+f]);
378:       y[r] = PetscLog10Real(ce->errors[r*ce->Nf+f]);
379:     }
380:     PetscLinearRegression(Nr+1, x, y, &slope, &intercept);
381:     /* Since h^{-dim} = N, lg err = s lg N + b = -s dim lg h + b */
382:     alpha[f] = -slope * dim;
383:   }
384:   PetscFree2(x, y);
385:   PetscFree2(dm, dof);
386:   /* Restore solver */
387:   SNESReset(snes);
388:   {
389:     /* PCReset() does not wipe out the level structure */
390:     KSP ksp;
391:     PC  pc;

393:     SNESGetKSP(snes, &ksp);
394:     KSPGetPC(ksp, &pc);
395:     PCMGSetLevels(pc, oldnlev, NULL);
396:     DMSetRefineLevel(ce->idm, oldlevel); /* The damn DMCoarsen() calls in PCMG can reset this */
397:   }
398:   SNESSetDM(snes, ce->idm);
399:   DMPlexSetSNESLocalFEM(ce->idm, ctx, ctx, ctx);
400:   SNESSetFromOptions(snes);
401:   return(0);
402: }

404: /*@
405:   PetscConvEstGetConvRate - Returns an estimate of the convergence rate for the discretization

407:   Not collective

409:   Input Parameter:
410: . ce   - The PetscConvEst object

412:   Output Parameter:
413: . alpha - The convergence rate for each field

415:   Note: The convergence rate alpha is defined by
416: $ || u_\Delta - u_exact || < C \Delta^alpha
417: where u_\Delta is the discrete solution, and Delta is a measure of the discretization size. We usually use h for the
418: spatial resolution and \Delta t for the temporal resolution.

420: We solve a series of problems using increasing resolution (refined meshes or decreased timesteps), calculate an error
421: based upon the exact solution in the DS, and then fit the result to our model above using linear regression.

423:   Options database keys:
424: + -snes_convergence_estimate : Execute convergence estimation inside SNESSolve() and print out the rate
425: - -ts_convergence_estimate : Execute convergence estimation inside TSSolve() and print out the rate

427:   Level: intermediate

429: .seealso: PetscConvEstSetSolver(), PetscConvEstCreate(), PetscConvEstGetConvRate(), SNESSolve(), TSSolve()
430: @*/
431: PetscErrorCode PetscConvEstGetConvRate(PetscConvEst ce, PetscReal alpha[])
432: {
433:   PetscInt       f;

437:   if (ce->event < 0) {PetscLogEventRegister("ConvEst Error", PETSC_OBJECT_CLASSID, &ce->event);}
438:   for (f = 0; f < ce->Nf; ++f) alpha[f] = 0.0;
439:   (*ce->ops->getconvrate)(ce, alpha);
440:   return(0);
441: }

443: /*@
444:   PetscConvEstRateView - Displays the convergence rate to a viewer

446:    Collective on SNES

448:    Parameter:
449: +  snes - iterative context obtained from SNESCreate()
450: .  alpha - the convergence rate for each field
451: -  viewer - the viewer to display the reason

453:    Options Database Keys:
454: .  -snes_convergence_estimate - print the convergence rate

456:    Level: developer

458: .seealso: PetscConvEstGetRate()
459: @*/
460: PetscErrorCode PetscConvEstRateView(PetscConvEst ce, const PetscReal alpha[], PetscViewer viewer)
461: {
462:   PetscBool      isAscii;

466:   PetscObjectTypeCompare((PetscObject) viewer, PETSCVIEWERASCII, &isAscii);
467:   if (isAscii) {
468:     PetscInt Nf = ce->Nf, f;

470:     PetscViewerASCIIAddTab(viewer, ((PetscObject) ce)->tablevel);
471:     PetscViewerASCIIPrintf(viewer, "L_2 convergence rate: ");
472:     if (Nf > 1) {PetscViewerASCIIPrintf(viewer, "[");}
473:     for (f = 0; f < Nf; ++f) {
474:       if (f > 0) {PetscViewerASCIIPrintf(viewer, ", ");}
475:       PetscViewerASCIIPrintf(viewer, "%#.2g", (double) alpha[f]);
476:     }
477:     if (Nf > 1) {PetscViewerASCIIPrintf(viewer, "]");}
478:     PetscViewerASCIIPrintf(viewer, "\n");
479:     PetscViewerASCIISubtractTab(viewer, ((PetscObject) ce)->tablevel);
480:   }
481:   return(0);
482: }

484: /*@
485:   PetscConvEstCreate - Create a PetscConvEst object

487:   Collective

489:   Input Parameter:
490: . comm - The communicator for the PetscConvEst object

492:   Output Parameter:
493: . ce   - The PetscConvEst object

495:   Level: beginner

497: .seealso: PetscConvEstDestroy(), PetscConvEstGetConvRate()
498: @*/
499: PetscErrorCode PetscConvEstCreate(MPI_Comm comm, PetscConvEst *ce)
500: {

505:   PetscSysInitializePackage();
506:   PetscHeaderCreate(*ce, PETSC_OBJECT_CLASSID, "PetscConvEst", "ConvergenceEstimator", "SNES", comm, PetscConvEstDestroy, PetscConvEstView);
507:   (*ce)->monitor = PETSC_FALSE;
508:   (*ce)->r       = 2.0;
509:   (*ce)->Nr      = 4;
510:   (*ce)->event   = -1;
511:   (*ce)->ops->setsolver    = PetscConvEstSetSNES_Private;
512:   (*ce)->ops->initguess    = PetscConvEstInitGuessSNES_Private;
513:   (*ce)->ops->computeerror = PetscConvEstComputeErrorSNES_Private;
514:   (*ce)->ops->getconvrate  = PetscConvEstGetConvRateSNES_Private;
515:   return(0);
516: }