Actual source code: fas.c

petsc-3.4.4 2014-03-13
  1: /* Defines the basic SNES object */
  2: #include <../src/snes/impls/fas/fasimpls.h>    /*I  "petscsnesfas.h"  I*/

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

  6: extern PetscErrorCode SNESDestroy_FAS(SNES snes);
  7: extern PetscErrorCode SNESSetUp_FAS(SNES snes);
  8: extern PetscErrorCode SNESSetFromOptions_FAS(SNES snes);
  9: extern PetscErrorCode SNESView_FAS(SNES snes, PetscViewer viewer);
 10: extern PetscErrorCode SNESSolve_FAS(SNES snes);
 11: extern PetscErrorCode SNESReset_FAS(SNES snes);
 12: extern PetscErrorCode SNESFASGalerkinDefaultFunction(SNES, Vec, Vec, void*);
 13: extern PetscErrorCode SNESFASCycleCreateSmoother_Private(SNES, SNES*);

 15: /*MC

 17: SNESFAS - Full Approximation Scheme nonlinear multigrid solver.

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

 23: Options Database:
 24: +   -snes_fas_levels -  The number of levels
 25: .   -snes_fas_cycles<1> -  The number of cycles -- 1 for V, 2 for W
 26: .   -snes_fas_type<additive, multiplicative>  -  Additive or multiplicative cycle
 27: .   -snes_fas_galerkin<PETSC_FALSE> -  Form coarse problems by projection back upon the fine problem
 28: .   -snes_fas_smoothup<1> -  The number of iterations of the post-smoother
 29: .   -snes_fas_smoothdown<1> -  The number of iterations of the pre-smoother
 30: .   -snes_fas_monitor -  Monitor progress of all of the levels
 31: .   -fas_levels_snes_ -  SNES options for all smoothers
 32: .   -fas_levels_cycle_snes_ -  SNES options for all cycles
 33: .   -fas_levels_i_snes_ -  SNES options for the smoothers on level i
 34: .   -fas_levels_i_cycle_snes_ - SNES options for the cycle on level i
 35: -   -fas_coarse_snes_ -  SNES options for the coarsest smoother

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

 42: Level: beginner

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

 49: PETSC_EXTERN PetscErrorCode SNESCreate_FAS(SNES snes)
 50: {
 51:   SNES_FAS       *fas;

 55:   snes->ops->destroy        = SNESDestroy_FAS;
 56:   snes->ops->setup          = SNESSetUp_FAS;
 57:   snes->ops->setfromoptions = SNESSetFromOptions_FAS;
 58:   snes->ops->view           = SNESView_FAS;
 59:   snes->ops->solve          = SNESSolve_FAS;
 60:   snes->ops->reset          = SNESReset_FAS;

 62:   snes->usesksp = PETSC_FALSE;
 63:   snes->usespc  = PETSC_FALSE;

 65:   if (!snes->tolerancesset) {
 66:     snes->max_funcs = 30000;
 67:     snes->max_its   = 10000;
 68:   }

 70:   PetscNewLog(snes, SNES_FAS, &fas);

 72:   snes->data                  = (void*) fas;
 73:   fas->level                  = 0;
 74:   fas->levels                 = 1;
 75:   fas->n_cycles               = 1;
 76:   fas->max_up_it              = 1;
 77:   fas->max_down_it            = 1;
 78:   fas->smoothu                = NULL;
 79:   fas->smoothd                = NULL;
 80:   fas->next                   = NULL;
 81:   fas->previous               = NULL;
 82:   fas->fine                   = snes;
 83:   fas->interpolate            = NULL;
 84:   fas->restrct                = NULL;
 85:   fas->inject                 = NULL;
 86:   fas->monitor                = NULL;
 87:   fas->usedmfornumberoflevels = PETSC_FALSE;
 88:   fas->fastype                = SNES_FAS_MULTIPLICATIVE;

 90:   fas->eventsmoothsetup    = 0;
 91:   fas->eventsmoothsolve    = 0;
 92:   fas->eventresidual       = 0;
 93:   fas->eventinterprestrict = 0;
 94:   return(0);
 95: }

 99: PetscErrorCode SNESReset_FAS(SNES snes)
100: {
101:   PetscErrorCode 0;
102:   SNES_FAS       * fas = (SNES_FAS*)snes->data;

105:   SNESDestroy(&fas->smoothu);
106:   SNESDestroy(&fas->smoothd);
107:   MatDestroy(&fas->inject);
108:   MatDestroy(&fas->interpolate);
109:   MatDestroy(&fas->restrct);
110:   VecDestroy(&fas->rscale);
111:   if (fas->next) SNESReset(fas->next);
112:   return(0);
113: }

117: PetscErrorCode SNESDestroy_FAS(SNES snes)
118: {
119:   SNES_FAS       * fas = (SNES_FAS*)snes->data;
120:   PetscErrorCode 0;

123:   /* recursively resets and then destroys */
124:   SNESReset(snes);
125:   if (fas->next) {
126:     SNESDestroy(&fas->next);
127:   }
128:   PetscFree(fas);
129:   return(0);
130: }

134: PetscErrorCode SNESSetUp_FAS(SNES snes)
135: {
136:   SNES_FAS       *fas = (SNES_FAS*) snes->data;
138:   VecScatter     injscatter;
139:   PetscInt       dm_levels;
140:   Vec            vec_sol, vec_func, vec_sol_update, vec_rhs; /* preserve these if they're set through the reset */
141:   SNES           next;
142:   PetscBool      isFine;
143:   SNESLineSearch linesearch;
144:   SNESLineSearch slinesearch;
145:   void           *lsprectx,*lspostctx;
146:   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
147:   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);

150:   SNESFASCycleIsFine(snes, &isFine);
151:   if (fas->usedmfornumberoflevels && isFine) {
152:     DMGetRefineLevel(snes->dm,&dm_levels);
153:     dm_levels++;
154:     if (dm_levels > fas->levels) {
155:       /* we don't want the solution and func vectors to be destroyed in the SNESReset when it's called in SNESFASSetLevels_FAS*/
156:       vec_sol              = snes->vec_sol;
157:       vec_func             = snes->vec_func;
158:       vec_sol_update       = snes->vec_sol_update;
159:       vec_rhs              = snes->vec_rhs;
160:       snes->vec_sol        = NULL;
161:       snes->vec_func       = NULL;
162:       snes->vec_sol_update = NULL;
163:       snes->vec_rhs        = NULL;

165:       /* reset the number of levels */
166:       SNESFASSetLevels(snes,dm_levels,NULL);
167:       SNESSetFromOptions(snes);

169:       snes->vec_sol        = vec_sol;
170:       snes->vec_func       = vec_func;
171:       snes->vec_rhs        = vec_rhs;
172:       snes->vec_sol_update = vec_sol_update;
173:     }
174:   }
175:   SNESFASCycleGetCorrection(snes, &next);
176:   if (!isFine) snes->gridsequence = 0; /* no grid sequencing inside the multigrid hierarchy! */

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

180:   /* set up the smoothers if they haven't already been set up */
181:   if (!fas->smoothd) {
182:     SNESFASCycleCreateSmoother_Private(snes, &fas->smoothd);
183:   }

185:   if (snes->dm) {
186:     /* set the smoother DMs properly */
187:     if (fas->smoothu) SNESSetDM(fas->smoothu, snes->dm);
188:     SNESSetDM(fas->smoothd, snes->dm);
189:     /* construct EVERYTHING from the DM -- including the progressive set of smoothers */
190:     if (next) {
191:       /* for now -- assume the DM and the evaluation functions have been set externally */
192:       if (!next->dm) {
193:         DMCoarsen(snes->dm, PetscObjectComm((PetscObject)next), &next->dm);
194:         SNESSetDM(next, next->dm);
195:       }
196:       /* set the interpolation and restriction from the DM */
197:       if (!fas->interpolate) {
198:         DMCreateInterpolation(next->dm, snes->dm, &fas->interpolate, &fas->rscale);
199:         if (!fas->restrct) {
200:           PetscObjectReference((PetscObject)fas->interpolate);
201:           fas->restrct = fas->interpolate;
202:         }
203:       }
204:       /* set the injection from the DM */
205:       if (!fas->inject) {
206:         DMCreateInjection(next->dm, snes->dm, &injscatter);
207:         MatCreateScatter(PetscObjectComm((PetscObject)snes), injscatter, &fas->inject);
208:         VecScatterDestroy(&injscatter);
209:       }
210:     }
211:   }
212:   /*pass the smoother, function, and jacobian up to the next level if it's not user set already */
213:   if (fas->galerkin) {
214:     if (next) {
215:       SNESSetFunction(next, NULL, SNESFASGalerkinDefaultFunction, next);
216:     }
217:     if (fas->smoothd && fas->level != fas->levels - 1) {
218:       SNESSetFunction(fas->smoothd, NULL, SNESFASGalerkinDefaultFunction, snes);
219:     }
220:     if (fas->smoothu && fas->level != fas->levels - 1) {
221:       SNESSetFunction(fas->smoothu, NULL, SNESFASGalerkinDefaultFunction, snes);
222:     }
223:   }

225:   /* sets the down (pre) smoother's default norm and sets it from options */
226:   if (fas->smoothd) {
227:     if (fas->level == 0 && fas->levels != 1) {
228:       SNESSetNormType(fas->smoothd, SNES_NORM_NONE);
229:     } else {
230:       SNESSetNormType(fas->smoothd, SNES_NORM_FINAL_ONLY);
231:     }
232:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)fas->smoothd);
233:     SNESSetFromOptions(fas->smoothd);
234:     SNESGetLineSearch(snes,&linesearch);
235:     SNESGetLineSearch(fas->smoothd,&slinesearch);
236:     SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
237:     SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
238:     SNESLineSearchSetPreCheck(slinesearch,precheck,lsprectx);
239:     SNESLineSearchSetPostCheck(slinesearch,postcheck,lspostctx);
240:     PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)slinesearch);

242:     fas->smoothd->vec_sol        = snes->vec_sol;
243:     PetscObjectReference((PetscObject)snes->vec_sol);
244:     fas->smoothd->vec_sol_update = snes->vec_sol_update;
245:     PetscObjectReference((PetscObject)snes->vec_sol_update);
246:     fas->smoothd->vec_func       = snes->vec_func;
247:     PetscObjectReference((PetscObject)snes->vec_func);

249:     if (fas->eventsmoothsetup) {PetscLogEventBegin(fas->eventsmoothsetup,0,0,0,0);}
250:     SNESSetUp(fas->smoothd);
251:     if (fas->eventsmoothsetup) {PetscLogEventEnd(fas->eventsmoothsetup,0,0,0,0);}
252:   }

254:   /* sets the up (post) smoother's default norm and sets it from options */
255:   if (fas->smoothu) {
256:     if (fas->level != fas->levels - 1) {
257:       SNESSetNormType(fas->smoothu, SNES_NORM_NONE);
258:     } else {
259:       SNESSetNormType(fas->smoothu, SNES_NORM_FINAL_ONLY);
260:     }
261:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)fas->smoothu);
262:     SNESSetFromOptions(fas->smoothu);
263:     SNESGetLineSearch(snes,&linesearch);
264:     SNESGetLineSearch(fas->smoothu,&slinesearch);
265:     SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
266:     SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
267:     SNESLineSearchSetPreCheck(slinesearch,precheck,lsprectx);
268:     SNESLineSearchSetPostCheck(slinesearch,postcheck,lspostctx);
269:     PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)slinesearch);

271:     fas->smoothu->vec_sol        = snes->vec_sol;
272:     PetscObjectReference((PetscObject)snes->vec_sol);
273:     fas->smoothu->vec_sol_update = snes->vec_sol_update;
274:     PetscObjectReference((PetscObject)snes->vec_sol_update);
275:     fas->smoothu->vec_func       = snes->vec_func;
276:     PetscObjectReference((PetscObject)snes->vec_func);

278:     if (fas->eventsmoothsetup) {PetscLogEventBegin(fas->eventsmoothsetup,0,0,0,0);}
279:     SNESSetUp(fas->smoothu);
280:     if (fas->eventsmoothsetup) {PetscLogEventEnd(fas->eventsmoothsetup,0,0,0,0);}

282:   }

284:   if (next) {
285:     /* gotta set up the solution vector for this to work */
286:     if (!next->vec_sol) {SNESFASCreateCoarseVec(snes,&next->vec_sol);}
287:     if (!next->vec_rhs) {SNESFASCreateCoarseVec(snes,&next->vec_rhs);}
288:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)next);
289:     SNESGetLineSearch(snes,&linesearch);
290:     SNESGetLineSearch(fas->next,&slinesearch);
291:     SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
292:     SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
293:     SNESLineSearchSetPreCheck(slinesearch,precheck,lsprectx);
294:     SNESLineSearchSetPostCheck(slinesearch,postcheck,lspostctx);
295:     PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)slinesearch);
296:     SNESSetUp(next);
297:   }
298:   /* setup FAS work vectors */
299:   if (fas->galerkin) {
300:     VecDuplicate(snes->vec_sol, &fas->Xg);
301:     VecDuplicate(snes->vec_sol, &fas->Fg);
302:   }
303:   return(0);
304: }

308: PetscErrorCode SNESSetFromOptions_FAS(SNES snes)
309: {
310:   SNES_FAS       *fas   = (SNES_FAS*) snes->data;
311:   PetscInt       levels = 1;
312:   PetscBool      flg    = PETSC_FALSE, upflg = PETSC_FALSE, downflg = PETSC_FALSE, monflg = PETSC_FALSE, galerkinflg = PETSC_FALSE;
314:   char           monfilename[PETSC_MAX_PATH_LEN];
315:   SNESFASType    fastype;
316:   const char     *optionsprefix;
317:   SNESLineSearch linesearch;
318:   PetscInt       m, n_up, n_down;
319:   SNES           next;
320:   PetscBool      isFine;

323:   SNESFASCycleIsFine(snes, &isFine);
324:   PetscOptionsHead("SNESFAS Options-----------------------------------");

326:   /* number of levels -- only process most options on the finest level */
327:   if (isFine) {
328:     PetscOptionsInt("-snes_fas_levels", "Number of Levels", "SNESFASSetLevels", levels, &levels, &flg);
329:     if (!flg && snes->dm) {
330:       DMGetRefineLevel(snes->dm,&levels);
331:       levels++;
332:       fas->usedmfornumberoflevels = PETSC_TRUE;
333:     }
334:     SNESFASSetLevels(snes, levels, NULL);
335:     fastype = fas->fastype;
336:     PetscOptionsEnum("-snes_fas_type","FAS correction type","SNESFASSetType",SNESFASTypes,(PetscEnum)fastype,(PetscEnum*)&fastype,&flg);
337:     if (flg) {
338:       SNESFASSetType(snes, fastype);
339:     }

341:     SNESGetOptionsPrefix(snes, &optionsprefix);
342:     PetscOptionsInt("-snes_fas_cycles","Number of cycles","SNESFASSetCycles",fas->n_cycles,&m,&flg);
343:     if (flg) {
344:       SNESFASSetCycles(snes, m);
345:     }

347:     PetscOptionsBool("-snes_fas_galerkin", "Form coarse problems with Galerkin","SNESFASSetGalerkin",fas->galerkin,&galerkinflg,&flg);
348:     if (flg) {
349:       SNESFASSetGalerkin(snes, galerkinflg);
350:     }

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

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

356:     PetscOptionsString("-snes_fas_monitor","Monitor FAS progress","SNESFASSetMonitor","stdout",monfilename,PETSC_MAX_PATH_LEN,&monflg);
357:     if (monflg) SNESFASSetMonitor(snes, PETSC_TRUE);

359:     flg    = PETSC_FALSE;
360:     monflg = PETSC_TRUE;
361:     PetscOptionsBool("-snes_fas_log","Log times for each FAS level","SNESFASSetLog",monflg,&monflg,&flg);
362:     if (flg) {SNESFASSetLog(snes,monflg);}
363:   }

365:   PetscOptionsTail();
366:   /* setup from the determined types if there is no pointwise procedure or smoother defined */
367:   if (upflg) {
368:     SNESFASSetNumberSmoothUp(snes,n_up);
369:   }
370:   if (downflg) {
371:     SNESFASSetNumberSmoothDown(snes,n_down);
372:   }

374:   /* set up the default line search for coarse grid corrections */
375:   if (fas->fastype == SNES_FAS_ADDITIVE) {
376:     if (!snes->linesearch) {
377:       SNESGetLineSearch(snes, &linesearch);
378:       SNESLineSearchSetType(linesearch, SNESLINESEARCHL2);
379:     }
380:   }

382:   SNESFASCycleGetCorrection(snes, &next);
383:   /* recursive option setting for the smoothers */
384:   if (next) {SNESSetFromOptions(next);}
385:   return(0);
386: }

388: #include <petscdraw.h>
391: PetscErrorCode SNESView_FAS(SNES snes, PetscViewer viewer)
392: {
393:   SNES_FAS       *fas = (SNES_FAS*) snes->data;
394:   PetscBool      isFine,iascii,isdraw;
395:   PetscInt       i;
397:   SNES           smoothu, smoothd, levelsnes;

400:   SNESFASCycleIsFine(snes, &isFine);
401:   if (isFine) {
402:     PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
403:     PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
404:     if (iascii) {
405:       PetscViewerASCIIPrintf(viewer, "FAS: type is %s, levels=%D, cycles=%D\n",  SNESFASTypes[fas->fastype], fas->levels, fas->n_cycles);
406:       if (fas->galerkin) {
407:         PetscViewerASCIIPrintf(viewer,"    Using Galerkin computed coarse grid function evaluation\n");
408:       } else {
409:         PetscViewerASCIIPrintf(viewer,"    Not using Galerkin computed coarse grid function evaluation\n");
410:       }
411:       for (i=0; i<fas->levels; i++) {
412:         SNESFASGetCycleSNES(snes, i, &levelsnes);
413:         SNESFASCycleGetSmootherUp(levelsnes, &smoothu);
414:         SNESFASCycleGetSmootherDown(levelsnes, &smoothd);
415:         if (!i) {
416:           PetscViewerASCIIPrintf(viewer,"Coarse grid solver -- level %D -------------------------------\n",i);
417:         } else {
418:           PetscViewerASCIIPrintf(viewer,"Down solver (pre-smoother) on level %D -------------------------------\n",i);
419:         }
420:         PetscViewerASCIIPushTab(viewer);
421:         if (smoothd) {
422:           SNESView(smoothd,viewer);
423:         } else {
424:           PetscViewerASCIIPrintf(viewer,"Not yet available\n");
425:         }
426:         PetscViewerASCIIPopTab(viewer);
427:         if (i && (smoothd == smoothu)) {
428:           PetscViewerASCIIPrintf(viewer,"Up solver (post-smoother) same as down solver (pre-smoother)\n");
429:         } else if (i) {
430:           PetscViewerASCIIPrintf(viewer,"Up solver (post-smoother) on level %D -------------------------------\n",i);
431:           PetscViewerASCIIPushTab(viewer);
432:           if (smoothu) {
433:             SNESView(smoothu,viewer);
434:           } else {
435:             PetscViewerASCIIPrintf(viewer,"Not yet available\n");
436:           }
437:           PetscViewerASCIIPopTab(viewer);
438:         }
439:       }
440:     } else if (isdraw) {
441:       PetscDraw draw;
442:       PetscReal x,w,y,bottom,th,wth;
443:       SNES_FAS  *curfas = fas;
444:       PetscViewerDrawGetDraw(viewer,0,&draw);
445:       PetscDrawGetCurrentPoint(draw,&x,&y);
446:       PetscDrawStringGetSize(draw,&wth,&th);
447:       bottom = y - th;
448:       while (curfas) {
449:         if (!curfas->smoothu) {
450:           PetscDrawPushCurrentPoint(draw,x,bottom);
451:           if (curfas->smoothd) SNESView(curfas->smoothd,viewer);
452:           PetscDrawPopCurrentPoint(draw);
453:         } else {
454:           w    = 0.5*PetscMin(1.0-x,x);
455:           PetscDrawPushCurrentPoint(draw,x-w,bottom);
456:           if (curfas->smoothd) SNESView(curfas->smoothd,viewer);
457:           PetscDrawPopCurrentPoint(draw);
458:           PetscDrawPushCurrentPoint(draw,x+w,bottom);
459:           if (curfas->smoothu) SNESView(curfas->smoothu,viewer);
460:           PetscDrawPopCurrentPoint(draw);
461:         }
462:         /* this is totally bogus but we have no way of knowing how low the previous one was draw to */
463:         bottom -= 5*th;
464:         if (curfas->next) curfas = (SNES_FAS*)curfas->next->data;
465:         else curfas = NULL;
466:       }
467:     }
468:   }
469:   return(0);
470: }

474: /*
475: Defines the action of the downsmoother
476:  */
477: PetscErrorCode SNESFASDownSmooth_Private(SNES snes, Vec B, Vec X, Vec F, PetscReal *fnorm)
478: {
479:   PetscErrorCode      0;
480:   SNESConvergedReason reason;
481:   Vec                 FPC;
482:   SNES                smoothd;
483:   SNES_FAS            *fas = (SNES_FAS*) snes->data;

486:   SNESFASCycleGetSmootherDown(snes, &smoothd);
487:   SNESSetInitialFunction(smoothd, F);
488:   SNESSetInitialFunctionNorm(smoothd, *fnorm);
489:   if (fas->eventsmoothsolve) {PetscLogEventBegin(fas->eventsmoothsolve,0,0,0,0);}
490:   SNESSolve(smoothd, B, X);
491:   if (fas->eventsmoothsolve) {PetscLogEventEnd(fas->eventsmoothsolve,0,0,0,0);}
492:   /* check convergence reason for the smoother */
493:   SNESGetConvergedReason(smoothd,&reason);
494:   if (reason < 0 && !(reason == SNES_DIVERGED_MAX_IT || reason == SNES_DIVERGED_LOCAL_MIN)) {
495:     snes->reason = SNES_DIVERGED_INNER;
496:     return(0);
497:   }
498:   SNESGetFunction(smoothd, &FPC, NULL, NULL);
499:   VecCopy(FPC, F);
500:   SNESGetFunctionNorm(smoothd, fnorm);
501:   return(0);
502: }


507: /*
508: Defines the action of the upsmoother
509:  */
510: PetscErrorCode SNESFASUpSmooth_Private(SNES snes, Vec B, Vec X, Vec F, PetscReal *fnorm)
511: {
512:   PetscErrorCode      0;
513:   SNESConvergedReason reason;
514:   Vec                 FPC;
515:   SNES                smoothu;
516:   SNES_FAS            *fas = (SNES_FAS*) snes->data;

519:   SNESFASCycleGetSmootherUp(snes, &smoothu);
520:   if (fas->eventsmoothsolve) {PetscLogEventBegin(fas->eventsmoothsolve,0,0,0,0);}
521:   SNESSolve(smoothu, B, X);
522:   if (fas->eventsmoothsolve) {PetscLogEventEnd(fas->eventsmoothsolve,0,0,0,0);}
523:   /* check convergence reason for the smoother */
524:   SNESGetConvergedReason(smoothu,&reason);
525:   if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
526:     snes->reason = SNES_DIVERGED_INNER;
527:     return(0);
528:   }
529:   SNESGetFunction(smoothu, &FPC, NULL, NULL);
530:   VecCopy(FPC, F);
531:   SNESGetFunctionNorm(smoothu, fnorm);
532:   return(0);
533: }

537: /*@
538:    SNESFASCreateCoarseVec - create Vec corresponding to a state vector on one level coarser than current level

540:    Collective

542:    Input Arguments:
543: .  snes - SNESFAS

545:    Output Arguments:
546: .  Xcoarse - vector on level one coarser than snes

548:    Level: developer

550: .seealso: SNESFASSetRestriction(), SNESFASRestrict()
551: @*/
552: PetscErrorCode SNESFASCreateCoarseVec(SNES snes,Vec *Xcoarse)
553: {
555:   SNES_FAS       *fas = (SNES_FAS*)snes->data;

558:   if (fas->rscale) {
559:     VecDuplicate(fas->rscale,Xcoarse);
560:   } else if (fas->inject) {
561:     MatGetVecs(fas->inject,Xcoarse,NULL);
562:   } else SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"Must set restriction or injection");
563:   return(0);
564: }

568: /*@
569:    SNESFASRestrict - restrict a Vec to the next coarser level

571:    Collective

573:    Input Arguments:
574: +  fine - SNES from which to restrict
575: -  Xfine - vector to restrict

577:    Output Arguments:
578: .  Xcoarse - result of restriction

580:    Level: developer

582: .seealso: SNESFASSetRestriction(), SNESFASSetInjection()
583: @*/
584: PetscErrorCode SNESFASRestrict(SNES fine,Vec Xfine,Vec Xcoarse)
585: {
587:   SNES_FAS       *fas = (SNES_FAS*)fine->data;

593:   if (fas->inject) {
594:     MatRestrict(fas->inject,Xfine,Xcoarse);
595:   } else {
596:     MatRestrict(fas->restrct,Xfine,Xcoarse);
597:     VecPointwiseMult(Xcoarse,fas->rscale,Xcoarse);
598:   }
599:   return(0);
600: }

604: /*

606: Performs the FAS coarse correction as:

608: fine problem: F(x) = 0
609: coarse problem: F^c(x) = b^c

611: b^c = F^c(I^c_fx^f - I^c_fF(x))

613:  */
614: PetscErrorCode SNESFASCoarseCorrection(SNES snes, Vec X, Vec F, Vec X_new)
615: {
616:   PetscErrorCode      ierr;
617:   Vec                 X_c, Xo_c, F_c, B_c;
618:   SNESConvergedReason reason;
619:   SNES                next;
620:   Mat                 restrct, interpolate;
621:   SNES_FAS            *fasc;

624:   SNESFASCycleGetCorrection(snes, &next);
625:   if (next) {
626:     fasc = (SNES_FAS*)next->data;

628:     SNESFASCycleGetRestriction(snes, &restrct);
629:     SNESFASCycleGetInterpolation(snes, &interpolate);

631:     X_c  = next->vec_sol;
632:     Xo_c = next->work[0];
633:     F_c  = next->vec_func;
634:     B_c  = next->vec_rhs;

636:     if (fasc->eventinterprestrict) {PetscLogEventBegin(fasc->eventinterprestrict,0,0,0,0);}
637:     SNESFASRestrict(snes,X,Xo_c);
638:     /* restrict the defect */
639:     MatRestrict(restrct, F, B_c);
640:     if (fasc->eventinterprestrict) {PetscLogEventEnd(fasc->eventinterprestrict,0,0,0,0);}

642:     if (fasc->eventresidual) {PetscLogEventBegin(fasc->eventresidual,0,0,0,0);}
643:     SNESComputeFunction(next, Xo_c, F_c);
644:     if (fasc->eventresidual) {PetscLogEventEnd(fasc->eventresidual,0,0,0,0);}

646:     /* solve the coarse problem corresponding to F^c(x^c) = b^c = F^c(Rx) - R(F(x) - b) */
647:     VecCopy(B_c, X_c);
648:     VecCopy(F_c, B_c);
649:     VecCopy(X_c, F_c);
650:     /* set initial guess of the coarse problem to the projected fine solution */
651:     VecCopy(Xo_c, X_c);

653:     /* recurse to the next level */
654:     SNESSetInitialFunction(next, F_c);
655:     SNESSolve(next, B_c, X_c);
656:     SNESGetConvergedReason(next,&reason);
657:     if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
658:       snes->reason = SNES_DIVERGED_INNER;
659:       return(0);
660:     }
661:     /* correct as x <- x + I(x^c - Rx)*/
662:     VecAXPY(X_c, -1.0, Xo_c);

664:     if (fasc->eventinterprestrict) {PetscLogEventBegin(fasc->eventinterprestrict,0,0,0,0);}
665:     MatInterpolateAdd(interpolate, X_c, X, X_new);
666:     if (fasc->eventinterprestrict) {PetscLogEventEnd(fasc->eventinterprestrict,0,0,0,0);}
667:   }
668:   return(0);
669: }

673: /*

675: The additive cycle looks like:

677: xhat = x
678: xhat = dS(x, b)
679: x = coarsecorrection(xhat, b_d)
680: x = x + nu*(xhat - x);
681: (optional) x = uS(x, b)

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

685:  */
686: PetscErrorCode SNESFASCycle_Additive(SNES snes, Vec X)
687: {
688:   Vec                 F, B, Xhat;
689:   Vec                 X_c, Xo_c, F_c, B_c;
690:   PetscErrorCode      ierr;
691:   SNESConvergedReason reason;
692:   PetscReal           xnorm, fnorm, ynorm;
693:   PetscBool           lssuccess;
694:   SNES                next;
695:   Mat                 restrct, interpolate;
696:   SNES_FAS            *fas = (SNES_FAS*)snes->data,*fasc;

699:   SNESFASCycleGetCorrection(snes, &next);
700:   F    = snes->vec_func;
701:   B    = snes->vec_rhs;
702:   Xhat = snes->work[1];
703:   VecCopy(X, Xhat);
704:   /* recurse first */
705:   if (next) {
706:     fasc = (SNES_FAS*)next->data;
707:     SNESFASCycleGetRestriction(snes, &restrct);
708:     SNESFASCycleGetInterpolation(snes, &interpolate);
709:     if (fas->eventresidual) {PetscLogEventBegin(fas->eventresidual,0,0,0,0);}
710:     SNESComputeFunction(snes, Xhat, F);
711:     if (fas->eventresidual) {PetscLogEventEnd(fas->eventresidual,0,0,0,0);}
712:     VecNorm(F, NORM_2, &fnorm);
713:     X_c  = next->vec_sol;
714:     Xo_c = next->work[0];
715:     F_c  = next->vec_func;
716:     B_c  = next->vec_rhs;

718:     SNESFASRestrict(snes,Xhat,Xo_c);
719:     /* restrict the defect */
720:     MatRestrict(restrct, F, B_c);

722:     /* solve the coarse problem corresponding to F^c(x^c) = b^c = Rb + F^c(Rx) - RF(x) */
723:     if (fasc->eventresidual) {PetscLogEventBegin(fasc->eventresidual,0,0,0,0);}
724:     SNESComputeFunction(next, Xo_c, F_c);
725:     if (fasc->eventresidual) {PetscLogEventEnd(fasc->eventresidual,0,0,0,0);}
726:     VecCopy(B_c, X_c);
727:     VecCopy(F_c, B_c);
728:     VecCopy(X_c, F_c);
729:     /* set initial guess of the coarse problem to the projected fine solution */
730:     VecCopy(Xo_c, X_c);

732:     /* recurse */
733:     SNESSetInitialFunction(next, F_c);
734:     SNESSolve(next, B_c, X_c);

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

739:     SNESGetConvergedReason(next,&reason);
740:     if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
741:       snes->reason = SNES_DIVERGED_INNER;
742:       return(0);
743:     }

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

749:     /* additive correction of the coarse direction*/
750:     SNESLineSearchApply(snes->linesearch, X, F, &fnorm, Xhat);
751:     SNESLineSearchGetSuccess(snes->linesearch, &lssuccess);
752:     if (!lssuccess) {
753:       if (++snes->numFailures >= snes->maxFailures) {
754:         snes->reason = SNES_DIVERGED_LINE_SEARCH;
755:         return(0);
756:       }
757:     }
758:     SNESLineSearchGetNorms(snes->linesearch, &xnorm, &snes->norm, &ynorm);
759:   } else {
760:     SNESFASDownSmooth_Private(snes, B, X, F, &snes->norm);
761:   }
762:   return(0);
763: }

767: /*

769: Defines the FAS cycle as:

771: fine problem: F(x) = 0
772: coarse problem: F^c(x) = b^c

774: b^c = F^c(I^c_fx^f - I^c_fF(x))

776: correction:

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

780:  */
781: PetscErrorCode SNESFASCycle_Multiplicative(SNES snes, Vec X)
782: {

785:   Vec            F,B;
786:   SNES_FAS       *fas = (SNES_FAS*)snes->data;

789:   F = snes->vec_func;
790:   B = snes->vec_rhs;
791:   /* pre-smooth -- just update using the pre-smoother */
792:   SNESFASDownSmooth_Private(snes, B, X, F, &snes->norm);
793:   if (fas->level != 0) {
794:     SNESFASCoarseCorrection(snes, X, F, X);
795:     SNESFASUpSmooth_Private(snes, B, X, F, &snes->norm);
796:   }
797:   return(0);
798: }


803: PetscErrorCode SNESSolve_FAS(SNES snes)
804: {
806:   PetscInt       i, maxits;
807:   Vec            X, F;
808:   PetscReal      fnorm;
809:   SNES_FAS       *fas = (SNES_FAS*)snes->data,*ffas;
810:   DM             dm;
811:   PetscBool      isFine;

814:   maxits       = snes->max_its;      /* maximum number of iterations */
815:   snes->reason = SNES_CONVERGED_ITERATING;
816:   X            = snes->vec_sol;
817:   F            = snes->vec_func;

819:   SNESFASCycleIsFine(snes, &isFine);
820:   /*norm setup */
821:   PetscObjectAMSTakeAccess((PetscObject)snes);
822:   snes->iter = 0;
823:   snes->norm = 0.;
824:   PetscObjectAMSGrantAccess((PetscObject)snes);
825:   if (!snes->vec_func_init_set) {
826:     if (fas->eventresidual) {PetscLogEventBegin(fas->eventresidual,0,0,0,0);}
827:     SNESComputeFunction(snes,X,F);
828:     if (fas->eventresidual) {PetscLogEventEnd(fas->eventresidual,0,0,0,0);}
829:     if (snes->domainerror) {
830:       snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN;
831:       return(0);
832:     }
833:   } else snes->vec_func_init_set = PETSC_FALSE;

835:   if (!snes->norm_init_set) {
836:     VecNorm(F, NORM_2, &fnorm); /* fnorm <- ||F||  */
837:     if (PetscIsInfOrNanReal(fnorm)) {
838:       snes->reason = SNES_DIVERGED_FNORM_NAN;
839:       return(0);
840:     }
841:   } else {
842:     fnorm               = snes->norm_init;
843:     snes->norm_init_set = PETSC_FALSE;
844:   }

846:   PetscObjectAMSTakeAccess((PetscObject)snes);
847:   snes->norm = fnorm;
848:   PetscObjectAMSGrantAccess((PetscObject)snes);
849:   SNESLogConvergenceHistory(snes,fnorm,0);
850:   SNESMonitor(snes,0,fnorm);

852:   /* set parameter for default relative tolerance convergence test */
853:   snes->ttol = fnorm*snes->rtol;
854:   /* test convergence */
855:   (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);
856:   if (snes->reason) return(0);


859:   if (isFine) {
860:     /* propagate scale-dependent data up the hierarchy */
861:     SNESGetDM(snes,&dm);
862:     for (ffas=fas; ffas->next; ffas=(SNES_FAS*)ffas->next->data) {
863:       DM dmcoarse;
864:       SNESGetDM(ffas->next,&dmcoarse);
865:       DMRestrict(dm,ffas->restrct,ffas->rscale,ffas->inject,dmcoarse);
866:       dm   = dmcoarse;
867:     }
868:   }

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

873:     if (snes->ops->update) {
874:       (*snes->ops->update)(snes, snes->iter);
875:     }
876:     if (fas->fastype == SNES_FAS_MULTIPLICATIVE) {
877:       SNESFASCycle_Multiplicative(snes, X);
878:     } else {
879:       SNESFASCycle_Additive(snes, X);
880:     }

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

885:     /* Monitor convergence */
886:     PetscObjectAMSTakeAccess((PetscObject)snes);
887:     snes->iter = i+1;
888:     PetscObjectAMSGrantAccess((PetscObject)snes);
889:     SNESLogConvergenceHistory(snes,snes->norm,0);
890:     SNESMonitor(snes,snes->iter,snes->norm);
891:     /* Test for convergence */
892:     if (isFine) {
893:       (*snes->ops->converged)(snes,snes->iter,0.0,0.0,snes->norm,&snes->reason,snes->cnvP);
894:       if (snes->reason) break;
895:     }
896:   }
897:   if (i == maxits) {
898:     PetscInfo1(snes, "Maximum number of iterations has been reached: %D\n", maxits);
899:     if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT;
900:   }
901:   return(0);
902: }