Actual source code: fas.c

petsc-3.11.2 2019-05-18
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  1: /* Defines the basic SNES object */
  2:  #include <../src/snes/impls/fas/fasimpls.h>

  4: const char *const SNESFASTypes[] = {"MULTIPLICATIVE","ADDITIVE","FULL","KASKADE","SNESFASType","SNES_FAS",0};

  6: static PetscErrorCode SNESReset_FAS(SNES snes)
  7: {
  8:   PetscErrorCode 0;
  9:   SNES_FAS       * fas = (SNES_FAS*)snes->data;

 12:   SNESDestroy(&fas->smoothu);
 13:   SNESDestroy(&fas->smoothd);
 14:   MatDestroy(&fas->inject);
 15:   MatDestroy(&fas->interpolate);
 16:   MatDestroy(&fas->restrct);
 17:   VecDestroy(&fas->rscale);
 18:   if (fas->galerkin) {
 19:     VecDestroy(&fas->Xg);
 20:     VecDestroy(&fas->Fg);
 21:   }
 22:   if (fas->next) {SNESReset(fas->next);}
 23:   return(0);
 24: }

 26: static PetscErrorCode SNESDestroy_FAS(SNES snes)
 27: {
 28:   SNES_FAS       * fas = (SNES_FAS*)snes->data;
 29:   PetscErrorCode 0;

 32:   /* recursively resets and then destroys */
 33:   SNESReset(snes);
 34:   if (fas->next) {
 35:     SNESDestroy(&fas->next);
 36:   }
 37:   PetscFree(fas);
 38:   return(0);
 39: }

 41: static PetscErrorCode SNESSetUp_FAS(SNES snes)
 42: {
 43:   SNES_FAS       *fas = (SNES_FAS*) snes->data;
 45:   PetscInt       dm_levels;
 46:   Vec            vec_sol, vec_func, vec_sol_update, vec_rhs; /* preserve these if they're set through the reset */
 47:   SNES           next;
 48:   PetscBool      isFine, hasCreateRestriction;
 49:   SNESLineSearch linesearch;
 50:   SNESLineSearch slinesearch;
 51:   void           *lsprectx,*lspostctx;
 52:   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
 53:   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);

 56:   SNESFASCycleIsFine(snes, &isFine);
 57:   if (fas->usedmfornumberoflevels && isFine) {
 58:     DMGetRefineLevel(snes->dm,&dm_levels);
 59:     dm_levels++;
 60:     if (dm_levels > fas->levels) {
 61:       /* we don't want the solution and func vectors to be destroyed in the SNESReset when it's called in SNESFASSetLevels_FAS*/
 62:       vec_sol              = snes->vec_sol;
 63:       vec_func             = snes->vec_func;
 64:       vec_sol_update       = snes->vec_sol_update;
 65:       vec_rhs              = snes->vec_rhs;
 66:       snes->vec_sol        = NULL;
 67:       snes->vec_func       = NULL;
 68:       snes->vec_sol_update = NULL;
 69:       snes->vec_rhs        = NULL;

 71:       /* reset the number of levels */
 72:       SNESFASSetLevels(snes,dm_levels,NULL);
 73:       SNESSetFromOptions(snes);

 75:       snes->vec_sol        = vec_sol;
 76:       snes->vec_func       = vec_func;
 77:       snes->vec_rhs        = vec_rhs;
 78:       snes->vec_sol_update = vec_sol_update;
 79:     }
 80:   }
 81:   SNESFASCycleGetCorrection(snes, &next);
 82:   if (!isFine) snes->gridsequence = 0; /* no grid sequencing inside the multigrid hierarchy! */

 84:   SNESSetWorkVecs(snes, 2); /* work vectors used for intergrid transfers */

 86:   /* set up the smoothers if they haven't already been set up */
 87:   if (!fas->smoothd) {
 88:     SNESFASCycleCreateSmoother_Private(snes, &fas->smoothd);
 89:   }

 91:   if (snes->dm) {
 92:     /* set the smoother DMs properly */
 93:     if (fas->smoothu) SNESSetDM(fas->smoothu, snes->dm);
 94:     SNESSetDM(fas->smoothd, snes->dm);
 95:     /* construct EVERYTHING from the DM -- including the progressive set of smoothers */
 96:     if (next) {
 97:       /* for now -- assume the DM and the evaluation functions have been set externally */
 98:       if (!next->dm) {
 99:         DMCoarsen(snes->dm, PetscObjectComm((PetscObject)next), &next->dm);
100:         SNESSetDM(next, next->dm);
101:       }
102:       /* set the interpolation and restriction from the DM */
103:       if (!fas->interpolate) {
104:         DMCreateInterpolation(next->dm, snes->dm, &fas->interpolate, &fas->rscale);
105:         if (!fas->restrct) {
106:           DMHasCreateRestriction(next->dm, &hasCreateRestriction);
107:           /* DM can create restrictions, use that */
108:           if (hasCreateRestriction) {
109:             DMCreateRestriction(next->dm, snes->dm, &fas->restrct);
110:           } else {
111:             PetscObjectReference((PetscObject)fas->interpolate);
112:             fas->restrct = fas->interpolate;
113:           }
114:         }
115:       }
116:       /* set the injection from the DM */
117:       if (!fas->inject) {
118:         PetscBool flg;
119:         DMHasCreateInjection(next->dm, &flg);
120:         if (flg) {
121:           DMCreateInjection(next->dm, snes->dm, &fas->inject);
122:         }
123:       }
124:     }
125:   }
126:   /*pass the smoother, function, and jacobian up to the next level if it's not user set already */
127:   if (fas->galerkin) {
128:     if (next) {
129:       SNESSetFunction(next, NULL, SNESFASGalerkinFunctionDefault, next);
130:     }
131:     if (fas->smoothd && fas->level != fas->levels - 1) {
132:       SNESSetFunction(fas->smoothd, NULL, SNESFASGalerkinFunctionDefault, snes);
133:     }
134:     if (fas->smoothu && fas->level != fas->levels - 1) {
135:       SNESSetFunction(fas->smoothu, NULL, SNESFASGalerkinFunctionDefault, snes);
136:     }
137:   }

139:   /* sets the down (pre) smoother's default norm and sets it from options */
140:   if (fas->smoothd) {
141:     if (fas->level == 0 && fas->levels != 1) {
142:       SNESSetNormSchedule(fas->smoothd, SNES_NORM_NONE);
143:     } else {
144:       SNESSetNormSchedule(fas->smoothd, SNES_NORM_FINAL_ONLY);
145:     }
146:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)fas->smoothd);
147:     SNESSetFromOptions(fas->smoothd);
148:     SNESGetLineSearch(snes,&linesearch);
149:     SNESGetLineSearch(fas->smoothd,&slinesearch);
150:     SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
151:     SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
152:     SNESLineSearchSetPreCheck(slinesearch,precheck,lsprectx);
153:     SNESLineSearchSetPostCheck(slinesearch,postcheck,lspostctx);
154:     PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)slinesearch);

156:     fas->smoothd->vec_sol        = snes->vec_sol;
157:     PetscObjectReference((PetscObject)snes->vec_sol);
158:     fas->smoothd->vec_sol_update = snes->vec_sol_update;
159:     PetscObjectReference((PetscObject)snes->vec_sol_update);
160:     fas->smoothd->vec_func       = snes->vec_func;
161:     PetscObjectReference((PetscObject)snes->vec_func);

163:     if (fas->eventsmoothsetup) {PetscLogEventBegin(fas->eventsmoothsetup,fas->smoothd,0,0,0);}
164:     SNESSetUp(fas->smoothd);
165:     if (fas->eventsmoothsetup) {PetscLogEventEnd(fas->eventsmoothsetup,fas->smoothd,0,0,0);}
166:   }

168:   /* sets the up (post) smoother's default norm and sets it from options */
169:   if (fas->smoothu) {
170:     if (fas->level != fas->levels - 1) {
171:       SNESSetNormSchedule(fas->smoothu, SNES_NORM_NONE);
172:     } else {
173:       SNESSetNormSchedule(fas->smoothu, SNES_NORM_FINAL_ONLY);
174:     }
175:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)fas->smoothu);
176:     SNESSetFromOptions(fas->smoothu);
177:     SNESGetLineSearch(snes,&linesearch);
178:     SNESGetLineSearch(fas->smoothu,&slinesearch);
179:     SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
180:     SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
181:     SNESLineSearchSetPreCheck(slinesearch,precheck,lsprectx);
182:     SNESLineSearchSetPostCheck(slinesearch,postcheck,lspostctx);
183:     PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)slinesearch);

185:     fas->smoothu->vec_sol        = snes->vec_sol;
186:     PetscObjectReference((PetscObject)snes->vec_sol);
187:     fas->smoothu->vec_sol_update = snes->vec_sol_update;
188:     PetscObjectReference((PetscObject)snes->vec_sol_update);
189:     fas->smoothu->vec_func       = snes->vec_func;
190:     PetscObjectReference((PetscObject)snes->vec_func);

192:     if (fas->eventsmoothsetup) {PetscLogEventBegin(fas->eventsmoothsetup,fas->smoothu,0,0,0);}
193:     SNESSetUp(fas->smoothu);
194:     if (fas->eventsmoothsetup) {PetscLogEventEnd(fas->eventsmoothsetup,fas->smoothu,0,0,0);}

196:   }

198:   if (next) {
199:     /* gotta set up the solution vector for this to work */
200:     if (!next->vec_sol) {SNESFASCreateCoarseVec(snes,&next->vec_sol);}
201:     if (!next->vec_rhs) {SNESFASCreateCoarseVec(snes,&next->vec_rhs);}
202:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)next);
203:     SNESGetLineSearch(snes,&linesearch);
204:     SNESGetLineSearch(fas->next,&slinesearch);
205:     SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
206:     SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
207:     SNESLineSearchSetPreCheck(slinesearch,precheck,lsprectx);
208:     SNESLineSearchSetPostCheck(slinesearch,postcheck,lspostctx);
209:     PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)slinesearch);
210:     SNESSetUp(next);
211:   }
212:   /* setup FAS work vectors */
213:   if (fas->galerkin) {
214:     VecDuplicate(snes->vec_sol, &fas->Xg);
215:     VecDuplicate(snes->vec_sol, &fas->Fg);
216:   }
217:   return(0);
218: }

220: static PetscErrorCode SNESSetFromOptions_FAS(PetscOptionItems *PetscOptionsObject,SNES snes)
221: {
222:   SNES_FAS       *fas   = (SNES_FAS*) snes->data;
223:   PetscInt       levels = 1;
224:   PetscBool      flg    = PETSC_FALSE, upflg = PETSC_FALSE, downflg = PETSC_FALSE, monflg = PETSC_FALSE, galerkinflg = PETSC_FALSE,continuationflg = PETSC_FALSE;
226:   SNESFASType    fastype;
227:   const char     *optionsprefix;
228:   SNESLineSearch linesearch;
229:   PetscInt       m, n_up, n_down;
230:   SNES           next;
231:   PetscBool      isFine;

234:   SNESFASCycleIsFine(snes, &isFine);
235:   PetscOptionsHead(PetscOptionsObject,"SNESFAS Options-----------------------------------");

237:   /* number of levels -- only process most options on the finest level */
238:   if (isFine) {
239:     PetscOptionsInt("-snes_fas_levels", "Number of Levels", "SNESFASSetLevels", levels, &levels, &flg);
240:     if (!flg && snes->dm) {
241:       DMGetRefineLevel(snes->dm,&levels);
242:       levels++;
243:       fas->usedmfornumberoflevels = PETSC_TRUE;
244:     }
245:     SNESFASSetLevels(snes, levels, NULL);
246:     fastype = fas->fastype;
247:     PetscOptionsEnum("-snes_fas_type","FAS correction type","SNESFASSetType",SNESFASTypes,(PetscEnum)fastype,(PetscEnum*)&fastype,&flg);
248:     if (flg) {
249:       SNESFASSetType(snes, fastype);
250:     }

252:     SNESGetOptionsPrefix(snes, &optionsprefix);
253:     PetscOptionsInt("-snes_fas_cycles","Number of cycles","SNESFASSetCycles",fas->n_cycles,&m,&flg);
254:     if (flg) {
255:       SNESFASSetCycles(snes, m);
256:     }
257:     PetscOptionsBool("-snes_fas_continuation","Corrected grid-sequence continuation","SNESFASSetContinuation",fas->continuation,&continuationflg,&flg);
258:     if (flg) {
259:       SNESFASSetContinuation(snes,continuationflg);
260:     }

262:     PetscOptionsBool("-snes_fas_galerkin", "Form coarse problems with Galerkin","SNESFASSetGalerkin",fas->galerkin,&galerkinflg,&flg);
263:     if (flg) {
264:       SNESFASSetGalerkin(snes, galerkinflg);
265:     }

267:     if (fas->fastype == SNES_FAS_FULL) {
268:       PetscOptionsBool("-snes_fas_full_downsweep","Smooth on the initial down sweep for full FAS cycles","SNESFASFullSetDownSweep",fas->full_downsweep,&fas->full_downsweep,&flg);
269:       if (flg) {SNESFASFullSetDownSweep(snes,fas->full_downsweep);}
270:     }

272:     PetscOptionsInt("-snes_fas_smoothup","Number of post-smoothing steps","SNESFASSetNumberSmoothUp",fas->max_up_it,&n_up,&upflg);

274:     PetscOptionsInt("-snes_fas_smoothdown","Number of pre-smoothing steps","SNESFASSetNumberSmoothDown",fas->max_down_it,&n_down,&downflg);

276:     {
277:       PetscViewer viewer;
278:       PetscViewerFormat format;
279:       PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_fas_monitor",&viewer,&format,&monflg);
280:       if (monflg) {
281:         PetscViewerAndFormat *vf;
282:         PetscViewerAndFormatCreate(viewer,format,&vf);
283:         PetscObjectDereference((PetscObject)viewer);
284:         SNESFASSetMonitor(snes,vf,PETSC_TRUE);
285:       }
286:     }
287:     flg    = PETSC_FALSE;
288:     monflg = PETSC_TRUE;
289:     PetscOptionsBool("-snes_fas_log","Log times for each FAS level","SNESFASSetLog",monflg,&monflg,&flg);
290:     if (flg) {SNESFASSetLog(snes,monflg);}
291:   }

293:   PetscOptionsTail();
294:   /* setup from the determined types if there is no pointwise procedure or smoother defined */
295:   if (upflg) {
296:     SNESFASSetNumberSmoothUp(snes,n_up);
297:   }
298:   if (downflg) {
299:     SNESFASSetNumberSmoothDown(snes,n_down);
300:   }

302:   /* set up the default line search for coarse grid corrections */
303:   if (fas->fastype == SNES_FAS_ADDITIVE) {
304:     if (!snes->linesearch) {
305:       SNESGetLineSearch(snes, &linesearch);
306:       SNESLineSearchSetType(linesearch, SNESLINESEARCHL2);
307:     }
308:   }

310:   SNESFASCycleGetCorrection(snes, &next);
311:   /* recursive option setting for the smoothers */
312:   if (next) {SNESSetFromOptions(next);}
313:   return(0);
314: }

316:  #include <petscdraw.h>
317: static PetscErrorCode SNESView_FAS(SNES snes, PetscViewer viewer)
318: {
319:   SNES_FAS       *fas = (SNES_FAS*) snes->data;
320:   PetscBool      isFine,iascii,isdraw;
321:   PetscInt       i;
323:   SNES           smoothu, smoothd, levelsnes;

326:   SNESFASCycleIsFine(snes, &isFine);
327:   if (isFine) {
328:     PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
329:     PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
330:     if (iascii) {
331:       PetscViewerASCIIPrintf(viewer, "  type is %s, levels=%D, cycles=%D\n",  SNESFASTypes[fas->fastype], fas->levels, fas->n_cycles);
332:       if (fas->galerkin) {
333:         PetscViewerASCIIPrintf(viewer,"  Using Galerkin computed coarse grid function evaluation\n");
334:       } else {
335:         PetscViewerASCIIPrintf(viewer,"  Not using Galerkin computed coarse grid function evaluation\n");
336:       }
337:       for (i=0; i<fas->levels; i++) {
338:         SNESFASGetCycleSNES(snes, i, &levelsnes);
339:         SNESFASCycleGetSmootherUp(levelsnes, &smoothu);
340:         SNESFASCycleGetSmootherDown(levelsnes, &smoothd);
341:         if (!i) {
342:           PetscViewerASCIIPrintf(viewer,"  Coarse grid solver -- level %D -------------------------------\n",i);
343:         } else {
344:           PetscViewerASCIIPrintf(viewer,"  Down solver (pre-smoother) on level %D -------------------------------\n",i);
345:         }
346:         PetscViewerASCIIPushTab(viewer);
347:         if (smoothd) {
348:           SNESView(smoothd,viewer);
349:         } else {
350:           PetscViewerASCIIPrintf(viewer,"Not yet available\n");
351:         }
352:         PetscViewerASCIIPopTab(viewer);
353:         if (i && (smoothd == smoothu)) {
354:           PetscViewerASCIIPrintf(viewer,"  Up solver (post-smoother) same as down solver (pre-smoother)\n");
355:         } else if (i) {
356:           PetscViewerASCIIPrintf(viewer,"  Up solver (post-smoother) on level %D -------------------------------\n",i);
357:           PetscViewerASCIIPushTab(viewer);
358:           if (smoothu) {
359:             SNESView(smoothu,viewer);
360:           } else {
361:             PetscViewerASCIIPrintf(viewer,"Not yet available\n");
362:           }
363:           PetscViewerASCIIPopTab(viewer);
364:         }
365:       }
366:     } else if (isdraw) {
367:       PetscDraw draw;
368:       PetscReal x,w,y,bottom,th,wth;
369:       SNES_FAS  *curfas = fas;
370:       PetscViewerDrawGetDraw(viewer,0,&draw);
371:       PetscDrawGetCurrentPoint(draw,&x,&y);
372:       PetscDrawStringGetSize(draw,&wth,&th);
373:       bottom = y - th;
374:       while (curfas) {
375:         if (!curfas->smoothu) {
376:           PetscDrawPushCurrentPoint(draw,x,bottom);
377:           if (curfas->smoothd) SNESView(curfas->smoothd,viewer);
378:           PetscDrawPopCurrentPoint(draw);
379:         } else {
380:           w    = 0.5*PetscMin(1.0-x,x);
381:           PetscDrawPushCurrentPoint(draw,x-w,bottom);
382:           if (curfas->smoothd) SNESView(curfas->smoothd,viewer);
383:           PetscDrawPopCurrentPoint(draw);
384:           PetscDrawPushCurrentPoint(draw,x+w,bottom);
385:           if (curfas->smoothu) SNESView(curfas->smoothu,viewer);
386:           PetscDrawPopCurrentPoint(draw);
387:         }
388:         /* this is totally bogus but we have no way of knowing how low the previous one was draw to */
389:         bottom -= 5*th;
390:         if (curfas->next) curfas = (SNES_FAS*)curfas->next->data;
391:         else curfas = NULL;
392:       }
393:     }
394:   }
395:   return(0);
396: }

398: /*
399: Defines the action of the downsmoother
400:  */
401: static PetscErrorCode SNESFASDownSmooth_Private(SNES snes, Vec B, Vec X, Vec F, PetscReal *fnorm)
402: {
403:   PetscErrorCode      0;
404:   SNESConvergedReason reason;
405:   Vec                 FPC;
406:   SNES                smoothd;
407:   PetscBool           flg;
408:   SNES_FAS            *fas = (SNES_FAS*) snes->data;

411:   SNESFASCycleGetSmootherDown(snes, &smoothd);
412:   SNESSetInitialFunction(smoothd, F);
413:   if (fas->eventsmoothsolve) {PetscLogEventBegin(fas->eventsmoothsolve,smoothd,B,X,0);}
414:   SNESSolve(smoothd, B, X);
415:   if (fas->eventsmoothsolve) {PetscLogEventEnd(fas->eventsmoothsolve,smoothd,B,X,0);}
416:   /* check convergence reason for the smoother */
417:   SNESGetConvergedReason(smoothd,&reason);
418:   if (reason < 0 && !(reason == SNES_DIVERGED_MAX_IT || reason == SNES_DIVERGED_LOCAL_MIN || reason == SNES_DIVERGED_LINE_SEARCH)) {
419:     snes->reason = SNES_DIVERGED_INNER;
420:     return(0);
421:   }

423:   SNESGetFunction(smoothd, &FPC, NULL, NULL);
424:   SNESGetAlwaysComputesFinalResidual(smoothd, &flg);
425:   if (!flg) {
426:     SNESComputeFunction(smoothd, X, FPC);
427:   }
428:   VecCopy(FPC, F);
429:   if (fnorm) {VecNorm(F,NORM_2,fnorm);}
430:   return(0);
431: }


434: /*
435: Defines the action of the upsmoother
436:  */
437: static PetscErrorCode SNESFASUpSmooth_Private(SNES snes, Vec B, Vec X, Vec F, PetscReal *fnorm)
438: {
439:   PetscErrorCode      0;
440:   SNESConvergedReason reason;
441:   Vec                 FPC;
442:   SNES                smoothu;
443:   PetscBool           flg;
444:   SNES_FAS            *fas = (SNES_FAS*) snes->data;

447:   SNESFASCycleGetSmootherUp(snes, &smoothu);
448:   if (fas->eventsmoothsolve) {PetscLogEventBegin(fas->eventsmoothsolve,smoothu,0,0,0);}
449:   SNESSolve(smoothu, B, X);
450:   if (fas->eventsmoothsolve) {PetscLogEventEnd(fas->eventsmoothsolve,smoothu,0,0,0);}
451:   /* check convergence reason for the smoother */
452:   SNESGetConvergedReason(smoothu,&reason);
453:   if (reason < 0 && !(reason == SNES_DIVERGED_MAX_IT || reason == SNES_DIVERGED_LOCAL_MIN || reason == SNES_DIVERGED_LINE_SEARCH)) {
454:     snes->reason = SNES_DIVERGED_INNER;
455:     return(0);
456:   }
457:   SNESGetFunction(smoothu, &FPC, NULL, NULL);
458:   SNESGetAlwaysComputesFinalResidual(smoothu, &flg);
459:   if (!flg) {
460:     SNESComputeFunction(smoothu, X, FPC);
461:   }
462:   VecCopy(FPC, F);
463:   if (fnorm) {VecNorm(F,NORM_2,fnorm);}
464:   return(0);
465: }

467: /*@
468:    SNESFASCreateCoarseVec - create Vec corresponding to a state vector on one level coarser than current level

470:    Collective

472:    Input Arguments:
473: .  snes - SNESFAS

475:    Output Arguments:
476: .  Xcoarse - vector on level one coarser than snes

478:    Level: developer

480: .seealso: SNESFASSetRestriction(), SNESFASRestrict()
481: @*/
482: PetscErrorCode SNESFASCreateCoarseVec(SNES snes,Vec *Xcoarse)
483: {
485:   SNES_FAS       *fas = (SNES_FAS*)snes->data;

488:   if (fas->rscale) {
489:     VecDuplicate(fas->rscale,Xcoarse);
490:   } else if (fas->inject) {
491:     MatCreateVecs(fas->inject,Xcoarse,NULL);
492:   } else SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"Must set restriction or injection");
493:   return(0);
494: }

496: /*@
497:    SNESFASRestrict - restrict a Vec to the next coarser level

499:    Collective

501:    Input Arguments:
502: +  fine - SNES from which to restrict
503: -  Xfine - vector to restrict

505:    Output Arguments:
506: .  Xcoarse - result of restriction

508:    Level: developer

510: .seealso: SNESFASSetRestriction(), SNESFASSetInjection()
511: @*/
512: PetscErrorCode SNESFASRestrict(SNES fine,Vec Xfine,Vec Xcoarse)
513: {
515:   SNES_FAS       *fas = (SNES_FAS*)fine->data;

521:   if (fas->inject) {
522:     MatRestrict(fas->inject,Xfine,Xcoarse);
523:   } else {
524:     MatRestrict(fas->restrct,Xfine,Xcoarse);
525:     VecPointwiseMult(Xcoarse,fas->rscale,Xcoarse);
526:   }
527:   return(0);
528: }

530: /*

532: Performs the FAS coarse correction as:

534: fine problem:   F(x) = b
535: coarse problem: F^c(x^c) = b^c

537: b^c = F^c(Rx) - R(F(x) - b)

539:  */
540: PetscErrorCode SNESFASCoarseCorrection(SNES snes, Vec X, Vec F, Vec X_new)
541: {
542:   PetscErrorCode      ierr;
543:   Vec                 X_c, Xo_c, F_c, B_c;
544:   SNESConvergedReason reason;
545:   SNES                next;
546:   Mat                 restrct, interpolate;
547:   SNES_FAS            *fasc;

550:   SNESFASCycleGetCorrection(snes, &next);
551:   if (next) {
552:     fasc = (SNES_FAS*)next->data;

554:     SNESFASCycleGetRestriction(snes, &restrct);
555:     SNESFASCycleGetInterpolation(snes, &interpolate);

557:     X_c  = next->vec_sol;
558:     Xo_c = next->work[0];
559:     F_c  = next->vec_func;
560:     B_c  = next->vec_rhs;

562:     if (fasc->eventinterprestrict) {PetscLogEventBegin(fasc->eventinterprestrict,snes,0,0,0);}
563:     SNESFASRestrict(snes, X, Xo_c);
564:     /* restrict the defect: R(F(x) - b) */
565:     MatRestrict(restrct, F, B_c);
566:     if (fasc->eventinterprestrict) {PetscLogEventEnd(fasc->eventinterprestrict,snes,0,0,0);}

568:     if (fasc->eventresidual) {PetscLogEventBegin(fasc->eventresidual,next,0,0,0);}
569:     /* F_c = F^c(Rx) - R(F(x) - b) since the second term was sitting in next->vec_rhs */
570:     SNESComputeFunction(next, Xo_c, F_c);
571:     if (fasc->eventresidual) {PetscLogEventEnd(fasc->eventresidual,next,0,0,0);}

573:     /* solve the coarse problem corresponding to F^c(x^c) = b^c = F^c(Rx) - R(F(x) - b) */
574:     VecCopy(B_c, X_c);
575:     VecCopy(F_c, B_c);
576:     VecCopy(X_c, F_c);
577:     /* set initial guess of the coarse problem to the projected fine solution */
578:     VecCopy(Xo_c, X_c);

580:     /* recurse to the next level */
581:     SNESSetInitialFunction(next, F_c);
582:     SNESSolve(next, B_c, X_c);
583:     SNESGetConvergedReason(next,&reason);
584:     if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
585:       snes->reason = SNES_DIVERGED_INNER;
586:       return(0);
587:     }
588:     /* correct as x <- x + I(x^c - Rx)*/
589:     VecAXPY(X_c, -1.0, Xo_c);

591:     if (fasc->eventinterprestrict) {PetscLogEventBegin(fasc->eventinterprestrict,snes,0,0,0);}
592:     MatInterpolateAdd(interpolate, X_c, X, X_new);
593:     PetscObjectSetName((PetscObject) X_c, "Coarse correction");
594:     VecViewFromOptions(X_c, NULL, "-fas_coarse_solution_view");
595:     PetscObjectSetName((PetscObject) X_new, "Updated Fine solution");
596:     VecViewFromOptions(X_new, NULL, "-fas_levels_1_solution_view");
597:     if (fasc->eventinterprestrict) {PetscLogEventEnd(fasc->eventinterprestrict,snes,0,0,0);}
598:   }
599:   return(0);
600: }

602: /*

604: The additive cycle looks like:

606: xhat = x
607: xhat = dS(x, b)
608: x = coarsecorrection(xhat, b_d)
609: x = x + nu*(xhat - x);
610: (optional) x = uS(x, b)

612: With the coarse RHS (defect correction) as below.

614:  */
615: static PetscErrorCode SNESFASCycle_Additive(SNES snes, Vec X)
616: {
617:   Vec                  F, B, Xhat;
618:   Vec                  X_c, Xo_c, F_c, B_c;
619:   PetscErrorCode       ierr;
620:   SNESConvergedReason  reason;
621:   PetscReal            xnorm, fnorm, ynorm;
622:   SNESLineSearchReason lsresult;
623:   SNES                 next;
624:   Mat                  restrct, interpolate;
625:   SNES_FAS             *fas = (SNES_FAS*)snes->data,*fasc;

628:   SNESFASCycleGetCorrection(snes, &next);
629:   F    = snes->vec_func;
630:   B    = snes->vec_rhs;
631:   Xhat = snes->work[1];
632:   VecCopy(X, Xhat);
633:   /* recurse first */
634:   if (next) {
635:     fasc = (SNES_FAS*)next->data;
636:     SNESFASCycleGetRestriction(snes, &restrct);
637:     SNESFASCycleGetInterpolation(snes, &interpolate);
638:     if (fas->eventresidual) {PetscLogEventBegin(fas->eventresidual,snes,0,0,0);}
639:     SNESComputeFunction(snes, Xhat, F);
640:     if (fas->eventresidual) {PetscLogEventEnd(fas->eventresidual,snes,0,0,0);}
641:     VecNorm(F, NORM_2, &fnorm);
642:     X_c  = next->vec_sol;
643:     Xo_c = next->work[0];
644:     F_c  = next->vec_func;
645:     B_c  = next->vec_rhs;

647:     SNESFASRestrict(snes,Xhat,Xo_c);
648:     /* restrict the defect */
649:     MatRestrict(restrct, F, B_c);

651:     /* solve the coarse problem corresponding to F^c(x^c) = b^c = Rb + F^c(Rx) - RF(x) */
652:     if (fasc->eventresidual) {PetscLogEventBegin(fasc->eventresidual,next,0,0,0);}
653:     SNESComputeFunction(next, Xo_c, F_c);
654:     if (fasc->eventresidual) {PetscLogEventEnd(fasc->eventresidual,next,0,0,0);}
655:     VecCopy(B_c, X_c);
656:     VecCopy(F_c, B_c);
657:     VecCopy(X_c, F_c);
658:     /* set initial guess of the coarse problem to the projected fine solution */
659:     VecCopy(Xo_c, X_c);

661:     /* recurse */
662:     SNESSetInitialFunction(next, F_c);
663:     SNESSolve(next, B_c, X_c);

665:     /* smooth on this level */
666:     SNESFASDownSmooth_Private(snes, B, X, F, &fnorm);

668:     SNESGetConvergedReason(next,&reason);
669:     if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
670:       snes->reason = SNES_DIVERGED_INNER;
671:       return(0);
672:     }

674:     /* correct as x <- x + I(x^c - Rx)*/
675:     VecAYPX(X_c, -1.0, Xo_c);
676:     MatInterpolate(interpolate, X_c, Xhat);

678:     /* additive correction of the coarse direction*/
679:     SNESLineSearchApply(snes->linesearch, X, F, &fnorm, Xhat);
680:     SNESLineSearchGetReason(snes->linesearch, &lsresult);
681:     SNESLineSearchGetNorms(snes->linesearch, &xnorm, &snes->norm, &ynorm);
682:     if (lsresult) {
683:       if (++snes->numFailures >= snes->maxFailures) {
684:         snes->reason = SNES_DIVERGED_LINE_SEARCH;
685:         return(0);
686:       }
687:     }
688:   } else {
689:     SNESFASDownSmooth_Private(snes, B, X, F, &snes->norm);
690:   }
691:   return(0);
692: }

694: /*

696: Defines the FAS cycle as:

698: fine problem: F(x) = b
699: coarse problem: F^c(x) = b^c

701: b^c = F^c(Rx) - R(F(x) - b)

703: correction:

705: x = x + I(x^c - Rx)

707:  */
708: static PetscErrorCode SNESFASCycle_Multiplicative(SNES snes, Vec X)
709: {

712:   Vec            F,B;
713:   SNES           next;

716:   F = snes->vec_func;
717:   B = snes->vec_rhs;
718:   /* pre-smooth -- just update using the pre-smoother */
719:   SNESFASCycleGetCorrection(snes,&next);
720:   SNESFASDownSmooth_Private(snes, B, X, F, &snes->norm);
721:   if (next) {
722:     SNESFASCoarseCorrection(snes, X, F, X);
723:     SNESFASUpSmooth_Private(snes, B, X, F, &snes->norm);
724:   }
725:   return(0);
726: }

728: static PetscErrorCode SNESFASCycleSetupPhase_Full(SNES snes)
729: {
730:   SNES           next;
731:   SNES_FAS       *fas = (SNES_FAS*)snes->data;
732:   PetscBool      isFine;

736:   /* pre-smooth -- just update using the pre-smoother */
737:   SNESFASCycleIsFine(snes,&isFine);
738:   SNESFASCycleGetCorrection(snes,&next);
739:   fas->full_stage = 0;
740:   if (next) {SNESFASCycleSetupPhase_Full(next);}
741:   return(0);
742: }

744: static PetscErrorCode SNESFASCycle_Full(SNES snes, Vec X)
745: {
747:   Vec            F,B;
748:   SNES_FAS       *fas = (SNES_FAS*)snes->data;
749:   PetscBool      isFine;
750:   SNES           next;

753:   F = snes->vec_func;
754:   B = snes->vec_rhs;
755:   SNESFASCycleIsFine(snes,&isFine);
756:   SNESFASCycleGetCorrection(snes,&next);

758:   if (isFine) {
759:     SNESFASCycleSetupPhase_Full(snes);
760:   }

762:   if (fas->full_stage == 0) {
763:     /* downsweep */
764:     if (next) {
765:       if (fas->level != 1) next->max_its += 1;
766:       if (fas->full_downsweep) {SNESFASDownSmooth_Private(snes,B,X,F,&snes->norm);}
767:       fas->full_downsweep = PETSC_TRUE;
768:       SNESFASCoarseCorrection(snes,X,F,X);
769:       SNESFASUpSmooth_Private(snes,B,X,F,&snes->norm);
770:       if (fas->level != 1) next->max_its -= 1;
771:     } else {
772:       /* The smoother on the coarse level is the coarse solver */
773:       SNESFASDownSmooth_Private(snes,B,X,F,&snes->norm);
774:     }
775:     fas->full_stage = 1;
776:   } else if (fas->full_stage == 1) {
777:     if (snes->iter == 0) {SNESFASDownSmooth_Private(snes,B,X,F,&snes->norm);}
778:     if (next) {
779:       SNESFASCoarseCorrection(snes,X,F,X);
780:       SNESFASUpSmooth_Private(snes,B,X,F,&snes->norm);
781:     }
782:   }
783:   /* final v-cycle */
784:   if (isFine) {
785:     if (next) {
786:       SNESFASCoarseCorrection(snes,X,F,X);
787:       SNESFASUpSmooth_Private(snes,B,X,F,&snes->norm);
788:     }
789:   }
790:   return(0);
791: }

793: static PetscErrorCode SNESFASCycle_Kaskade(SNES snes, Vec X)
794: {
796:   Vec            F,B;
797:   SNES           next;

800:   F = snes->vec_func;
801:   B = snes->vec_rhs;
802:   SNESFASCycleGetCorrection(snes,&next);
803:   if (next) {
804:     SNESFASCoarseCorrection(snes,X,F,X);
805:     SNESFASUpSmooth_Private(snes,B,X,F,&snes->norm);
806:   } else {
807:     SNESFASDownSmooth_Private(snes,B,X,F,&snes->norm);
808:   }
809:   return(0);
810: }

812: PetscBool SNEScite = PETSC_FALSE;
813: const char SNESCitation[] = "@techreport{pbmkbsxt2012,\n"
814:                             "  title = {Composing Scalable Nonlinear Algebraic Solvers},\n"
815:                             "  author = {Peter Brune and Mathew Knepley and Barry Smith and Xuemin Tu},\n"
816:                             "  year = 2013,\n"
817:                             "  type = Preprint,\n"
818:                             "  number = {ANL/MCS-P2010-0112},\n"
819:                             "  institution = {Argonne National Laboratory}\n}\n";

821: static PetscErrorCode SNESSolve_FAS(SNES snes)
822: {
824:   PetscInt       i, maxits;
825:   Vec            X, F;
826:   PetscReal      fnorm;
827:   SNES_FAS       *fas = (SNES_FAS*)snes->data,*ffas;
828:   DM             dm;
829:   PetscBool      isFine;


833:   if (snes->xl || snes->xu || snes->ops->computevariablebounds) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE, "SNES solver %s does not support bounds", ((PetscObject)snes)->type_name);

835:   PetscCitationsRegister(SNESCitation,&SNEScite);
836:   maxits       = snes->max_its;      /* maximum number of iterations */
837:   snes->reason = SNES_CONVERGED_ITERATING;
838:   X            = snes->vec_sol;
839:   F            = snes->vec_func;

841:   SNESFASCycleIsFine(snes, &isFine);
842:   /*norm setup */
843:   PetscObjectSAWsTakeAccess((PetscObject)snes);
844:   snes->iter = 0;
845:   snes->norm = 0.;
846:   PetscObjectSAWsGrantAccess((PetscObject)snes);
847:   if (!snes->vec_func_init_set) {
848:     if (fas->eventresidual) {PetscLogEventBegin(fas->eventresidual,snes,0,0,0);}
849:     SNESComputeFunction(snes,X,F);
850:     if (fas->eventresidual) {PetscLogEventEnd(fas->eventresidual,snes,0,0,0);}
851:   } else snes->vec_func_init_set = PETSC_FALSE;

853:   VecNorm(F, NORM_2, &fnorm); /* fnorm <- ||F||  */
854:   SNESCheckFunctionNorm(snes,fnorm);
855:   PetscObjectSAWsTakeAccess((PetscObject)snes);
856:   snes->norm = fnorm;
857:   PetscObjectSAWsGrantAccess((PetscObject)snes);
858:   SNESLogConvergenceHistory(snes,fnorm,0);
859:   SNESMonitor(snes,0,fnorm);

861:   /* test convergence */
862:   (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);
863:   if (snes->reason) return(0);


866:   if (isFine) {
867:     /* propagate scale-dependent data up the hierarchy */
868:     SNESGetDM(snes,&dm);
869:     for (ffas=fas; ffas->next; ffas=(SNES_FAS*)ffas->next->data) {
870:       DM dmcoarse;
871:       SNESGetDM(ffas->next,&dmcoarse);
872:       DMRestrict(dm,ffas->restrct,ffas->rscale,ffas->inject,dmcoarse);
873:       dm   = dmcoarse;
874:     }
875:   }

877:   for (i = 0; i < maxits; i++) {
878:     /* Call general purpose update function */

880:     if (snes->ops->update) {
881:       (*snes->ops->update)(snes, snes->iter);
882:     }
883:     if (fas->fastype == SNES_FAS_MULTIPLICATIVE) {
884:       SNESFASCycle_Multiplicative(snes, X);
885:     } else if (fas->fastype == SNES_FAS_ADDITIVE) {
886:       SNESFASCycle_Additive(snes, X);
887:     } else if (fas->fastype == SNES_FAS_FULL) {
888:       SNESFASCycle_Full(snes, X);
889:     } else if (fas->fastype ==SNES_FAS_KASKADE) {
890:       SNESFASCycle_Kaskade(snes, X);
891:     } else SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"Unsupported FAS type");

893:     /* check for FAS cycle divergence */
894:     if (snes->reason != SNES_CONVERGED_ITERATING) return(0);

896:     /* Monitor convergence */
897:     PetscObjectSAWsTakeAccess((PetscObject)snes);
898:     snes->iter = i+1;
899:     PetscObjectSAWsGrantAccess((PetscObject)snes);
900:     SNESLogConvergenceHistory(snes,snes->norm,0);
901:     SNESMonitor(snes,snes->iter,snes->norm);
902:     /* Test for convergence */
903:     if (isFine) {
904:       (*snes->ops->converged)(snes,snes->iter,0.0,0.0,snes->norm,&snes->reason,snes->cnvP);
905:       if (snes->reason) break;
906:     }
907:   }
908:   if (i == maxits) {
909:     PetscInfo1(snes, "Maximum number of iterations has been reached: %D\n", maxits);
910:     if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT;
911:   }
912:   return(0);
913: }

915: /*MC

917: SNESFAS - Full Approximation Scheme nonlinear multigrid solver.

919:    The nonlinear problem is solved by correction using coarse versions
920:    of the nonlinear problem.  This problem is perturbed so that a projected
921:    solution of the fine problem elicits no correction from the coarse problem.

923: Options Database:
924: +   -snes_fas_levels -  The number of levels
925: .   -snes_fas_cycles<1> -  The number of cycles -- 1 for V, 2 for W
926: .   -snes_fas_type<additive,multiplicative,full,kaskade>  -  Additive or multiplicative cycle
927: .   -snes_fas_galerkin<PETSC_FALSE> -  Form coarse problems by projection back upon the fine problem
928: .   -snes_fas_smoothup<1> -  The number of iterations of the post-smoother
929: .   -snes_fas_smoothdown<1> -  The number of iterations of the pre-smoother
930: .   -snes_fas_monitor -  Monitor progress of all of the levels
931: .   -snes_fas_full_downsweep<PETSC_FALSE> - call the downsmooth on the initial downsweep of full FAS
932: .   -fas_levels_snes_ -  SNES options for all smoothers
933: .   -fas_levels_cycle_snes_ -  SNES options for all cycles
934: .   -fas_levels_i_snes_ -  SNES options for the smoothers on level i
935: .   -fas_levels_i_cycle_snes_ - SNES options for the cycle on level i
936: -   -fas_coarse_snes_ -  SNES options for the coarsest smoother

938: Notes:
939:    The organization of the FAS solver is slightly different from the organization of PCMG
940:    As each level has smoother SNES instances(down and potentially up) and a cycle SNES instance.
941:    The cycle SNES instance may be used for monitoring convergence on a particular level.

943: Level: beginner

945:    References:
946: . 1. -  Peter R. Brune, Matthew G. Knepley, Barry F. Smith, and Xuemin Tu, "Composing Scalable Nonlinear Algebraic Solvers",
947:    SIAM Review, 57(4), 2015

949: .seealso: PCMG, SNESCreate(), SNES, SNESSetType(), SNESType (for list of available types)
950: M*/

952: PETSC_EXTERN PetscErrorCode SNESCreate_FAS(SNES snes)
953: {
954:   SNES_FAS       *fas;

958:   snes->ops->destroy        = SNESDestroy_FAS;
959:   snes->ops->setup          = SNESSetUp_FAS;
960:   snes->ops->setfromoptions = SNESSetFromOptions_FAS;
961:   snes->ops->view           = SNESView_FAS;
962:   snes->ops->solve          = SNESSolve_FAS;
963:   snes->ops->reset          = SNESReset_FAS;

965:   snes->usesksp = PETSC_FALSE;
966:   snes->usesnpc = PETSC_FALSE;

968:   if (!snes->tolerancesset) {
969:     snes->max_funcs = 30000;
970:     snes->max_its   = 10000;
971:   }

973:   snes->alwayscomputesfinalresidual = PETSC_TRUE;

975:   PetscNewLog(snes,&fas);

977:   snes->data                  = (void*) fas;
978:   fas->level                  = 0;
979:   fas->levels                 = 1;
980:   fas->n_cycles               = 1;
981:   fas->max_up_it              = 1;
982:   fas->max_down_it            = 1;
983:   fas->smoothu                = NULL;
984:   fas->smoothd                = NULL;
985:   fas->next                   = NULL;
986:   fas->previous               = NULL;
987:   fas->fine                   = snes;
988:   fas->interpolate            = NULL;
989:   fas->restrct                = NULL;
990:   fas->inject                 = NULL;
991:   fas->usedmfornumberoflevels = PETSC_FALSE;
992:   fas->fastype                = SNES_FAS_MULTIPLICATIVE;
993:   fas->full_downsweep         = PETSC_FALSE;

995:   fas->eventsmoothsetup    = 0;
996:   fas->eventsmoothsolve    = 0;
997:   fas->eventresidual       = 0;
998:   fas->eventinterprestrict = 0;
999:   return(0);
1000: }