Date: 2013-07-02T14:49:30+00:00

Actual source code: snesngmres.c
petsc-3.4.2 2013-07-02

      1: #include <../src/snes/impls/ngmres/snesngmres.h> /*I "petscsnes.h" I*/
      2: #include <petscblaslapack.h>

      4: const char *const SNESNGMRESRestartTypes[] = {"NONE","PERIODIC","DIFFERENCE","SNESNGMRESRestartType","SNES_NGMRES_RESTART_",0};
      5: const char *const SNESNGMRESSelectTypes[] = {"NONE","DIFFERENCE","LINESEARCH","SNESNGMRESSelectType","SNES_NGMRES_SELECT_",0};

      9: PetscErrorCode SNESReset_NGMRES(SNES snes)
     10: {
     11:   SNES_NGMRES    *ngmres = (SNES_NGMRES*) snes->data;

     15:   VecDestroyVecs(ngmres->msize,&ngmres->Fdot);
     16:   VecDestroyVecs(ngmres->msize,&ngmres->Xdot);
     17:   SNESLineSearchDestroy(&ngmres->additive_linesearch);
     18:   return(0);
     19: }

     23: PetscErrorCode SNESDestroy_NGMRES(SNES snes)
     24: {
     26:   SNES_NGMRES    *ngmres = (SNES_NGMRES*)snes->data;

     29:   SNESReset_NGMRES(snes);
     30:   PetscFree5(ngmres->h,ngmres->beta,ngmres->xi,ngmres->fnorms,ngmres->q);
     31:   PetscFree(ngmres->s);
     32:   PetscFree(ngmres->xnorms);
     33: #if PETSC_USE_COMPLEX
     34:   PetscFree(ngmres->rwork);
     35: #endif
     36:   PetscFree(ngmres->work);
     37:   PetscFree(snes->data);
     38:   return(0);
     39: }

     43: PetscErrorCode SNESSetUp_NGMRES(SNES snes)
     44: {
     45:   SNES_NGMRES    *ngmres = (SNES_NGMRES*) snes->data;
     46:   const char     *optionsprefix;
     47:   PetscInt       msize,hsize;

     51:   SNESSetWorkVecs(snes,5);
     52:   if (!ngmres->Xdot) {VecDuplicateVecs(snes->vec_sol,ngmres->msize,&ngmres->Xdot);}
     53:   if (!ngmres->Fdot) {VecDuplicateVecs(snes->vec_sol,ngmres->msize,&ngmres->Fdot);}
     54:   if (!ngmres->setup_called) {
     55:     msize = ngmres->msize;          /* restart size */
     56:     hsize = msize * msize;

     58:     /* explicit least squares minimization solve */
     59:     PetscMalloc5(hsize,PetscScalar,&ngmres->h,
     60:                         msize,PetscScalar,&ngmres->beta,
     61:                         msize,PetscScalar,&ngmres->xi,
     62:                         msize,PetscReal, &ngmres->fnorms,
     63:                         hsize,PetscScalar,&ngmres->q);
     64:     if (ngmres->singlereduction) {
     65:       PetscMalloc(msize*sizeof(PetscReal),&ngmres->xnorms);
     66:     }
     67:     ngmres->nrhs  = 1;
     68:     ngmres->lda   = msize;
     69:     ngmres->ldb   = msize;
     70:     PetscMalloc(msize*sizeof(PetscScalar),&ngmres->s);
     71:     PetscMemzero(ngmres->h,   hsize*sizeof(PetscScalar));
     72:     PetscMemzero(ngmres->q,   hsize*sizeof(PetscScalar));
     73:     PetscMemzero(ngmres->xi,  msize*sizeof(PetscScalar));
     74:     PetscMemzero(ngmres->beta,msize*sizeof(PetscScalar));
     75:     ngmres->lwork = 12*msize;
     76: #if PETSC_USE_COMPLEX
     77:     PetscMalloc(sizeof(PetscReal)*ngmres->lwork,&ngmres->rwork);
     78: #endif
     79:     PetscMalloc(sizeof(PetscScalar)*ngmres->lwork,&ngmres->work);
     80:   }

     82:   /* linesearch setup */
     83:   SNESGetOptionsPrefix(snes,&optionsprefix);

     85:   if (ngmres->select_type == SNES_NGMRES_SELECT_LINESEARCH) {
     86:     SNESLineSearchCreate(PetscObjectComm((PetscObject)snes),&ngmres->additive_linesearch);
     87:     SNESLineSearchSetSNES(ngmres->additive_linesearch,snes);
     88:     SNESLineSearchSetType(ngmres->additive_linesearch,SNESLINESEARCHL2);
     89:     SNESLineSearchAppendOptionsPrefix(ngmres->additive_linesearch,"additive_");
     90:     SNESLineSearchAppendOptionsPrefix(ngmres->additive_linesearch,optionsprefix);
     91:     SNESLineSearchSetFromOptions(ngmres->additive_linesearch);
     92:   }

     94:   ngmres->setup_called = PETSC_TRUE;
     95:   return(0);
     96: }

    100: PetscErrorCode SNESSetFromOptions_NGMRES(SNES snes)
    101: {
    102:   SNES_NGMRES    *ngmres = (SNES_NGMRES*) snes->data;
    104:   PetscBool      debug;
    105:   SNESLineSearch linesearch;

    108:   PetscOptionsHead("SNES NGMRES options");
    109:   PetscOptionsEnum("-snes_ngmres_select_type","Select type","SNESNGMRESSetSelectType",SNESNGMRESSelectTypes,
    110:                           (PetscEnum)ngmres->select_type,(PetscEnum*)&ngmres->select_type,NULL);
    111:   PetscOptionsEnum("-snes_ngmres_restart_type","Restart type","SNESNGMRESSetRestartType",SNESNGMRESRestartTypes,
    112:                           (PetscEnum)ngmres->restart_type,(PetscEnum*)&ngmres->restart_type,NULL);
    113:   PetscOptionsBool("-snes_ngmres_candidate", "Use candidate storage",              "SNES",ngmres->candidate,&ngmres->candidate,NULL);
    114:   PetscOptionsBool("-snes_ngmres_approxfunc","Linearly approximate the function", "SNES",ngmres->approxfunc,&ngmres->approxfunc,NULL);
    115:   PetscOptionsInt("-snes_ngmres_m",          "Number of directions",               "SNES",ngmres->msize,&ngmres->msize,NULL);
    116:   PetscOptionsInt("-snes_ngmres_restart",    "Iterations before forced restart",   "SNES",ngmres->restart_periodic,&ngmres->restart_periodic,NULL);
    117:   PetscOptionsInt("-snes_ngmres_restart_it", "Tolerance iterations before restart","SNES",ngmres->restart_it,&ngmres->restart_it,NULL);
    118:   PetscOptionsBool("-snes_ngmres_monitor",   "Monitor actions of NGMRES",          "SNES",ngmres->monitor ? PETSC_TRUE : PETSC_FALSE,&debug,NULL);
    119:   if (debug) {
    120:     ngmres->monitor = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes));
    121:   }
    122:   PetscOptionsReal("-snes_ngmres_gammaA",    "Residual selection constant",   "SNES",ngmres->gammaA,&ngmres->gammaA,NULL);
    123:   PetscOptionsReal("-snes_ngmres_gammaC",    "Residual restart constant",     "SNES",ngmres->gammaC,&ngmres->gammaC,NULL);
    124:   PetscOptionsReal("-snes_ngmres_epsilonB",  "Difference selection constant", "SNES",ngmres->epsilonB,&ngmres->epsilonB,NULL);
    125:   PetscOptionsReal("-snes_ngmres_deltaB",    "Difference residual selection constant", "SNES",ngmres->deltaB,&ngmres->deltaB,NULL);
    126:   PetscOptionsBool("-snes_ngmres_single_reduction", "Aggregate reductions",  "SNES",ngmres->singlereduction,&ngmres->singlereduction,NULL);
    127:   PetscOptionsTail();
    128:   if ((ngmres->gammaA > ngmres->gammaC) && (ngmres->gammaC > 2.)) ngmres->gammaC = ngmres->gammaA;

    130:   /* set the default type of the line search if the user hasn't already. */
    131:   if (!snes->linesearch) {
    132:     SNESGetLineSearch(snes,&linesearch);
    133:     SNESLineSearchSetType(linesearch,SNESLINESEARCHBASIC);
    134:   }
    135:   return(0);
    136: }

    140: PetscErrorCode SNESView_NGMRES(SNES snes,PetscViewer viewer)
    141: {
    142:   SNES_NGMRES    *ngmres = (SNES_NGMRES*) snes->data;
    143:   PetscBool      iascii;

    147:   PetscObjectTypeCompare((PetscObject) viewer,PETSCVIEWERASCII,&iascii);
    148:   if (iascii) {
    149:     PetscViewerASCIIPrintf(viewer,"  Number of stored past updates: %d\n", ngmres->msize);
    150:     PetscViewerASCIIPrintf(viewer,"  Residual selection: gammaA=%1.0e, gammaC=%1.0e\n",ngmres->gammaA,ngmres->gammaC);
    151:     PetscViewerASCIIPrintf(viewer,"  Difference restart: epsilonB=%1.0e, deltaB=%1.0e\n",ngmres->epsilonB,ngmres->deltaB);
    152:   }
    153:   return(0);
    154: }

    158: PetscErrorCode SNESSolve_NGMRES(SNES snes)
    159: {

    161:   SNES_NGMRES *ngmres = (SNES_NGMRES*) snes->data;
    162:   /* present solution, residual, and preconditioned residual */
    163:   Vec X,F,B,D,Y;

    165:   /* candidate linear combination answers */
    166:   Vec XA,FA,XM,FM,FPC;

    168:   /* coefficients and RHS to the minimization problem */
    169:   PetscReal fnorm,fMnorm,fAnorm;
    170:   PetscInt  k,k_restart,l,ivec,restart_count = 0;

    172:   /* solution selection data */
    173:   PetscBool selectRestart;
    174:   PetscReal dnorm,dminnorm = 0.0;
    175:   PetscReal fminnorm,xnorm,ynorm;

    177:   SNESConvergedReason reason;
    178:   PetscBool           lssucceed;
    179:   PetscErrorCode      ierr;

    182:   /* variable initialization */
    183:   snes->reason = SNES_CONVERGED_ITERATING;
    184:   X            = snes->vec_sol;
    185:   F            = snes->vec_func;
    186:   B            = snes->vec_rhs;
    187:   XA           = snes->vec_sol_update;
    188:   FA           = snes->work[0];
    189:   D            = snes->work[1];

    191:   /* work for the line search */
    192:   Y  = snes->work[2];
    193:   XM = snes->work[3];
    194:   FM = snes->work[4];

    196:   PetscObjectAMSTakeAccess((PetscObject)snes);
    197:   snes->iter = 0;
    198:   snes->norm = 0.;
    199:   PetscObjectAMSGrantAccess((PetscObject)snes);

    201:   /* initialization */

    203:   /* r = F(x) */
    204:   if (!snes->vec_func_init_set) {
    205:     SNESComputeFunction(snes,X,F);
    206:     if (snes->domainerror) {
    207:       snes->reason = SNES_DIVERGED_FUNCTION_DOMAIN;
    208:       return(0);
    209:     }
    210:   } else snes->vec_func_init_set = PETSC_FALSE;

    212:   if (!snes->norm_init_set) {
    213:     VecNorm(F,NORM_2,&fnorm);
    214:     if (PetscIsInfOrNanReal(fnorm)) {
    215:       snes->reason = SNES_DIVERGED_FNORM_NAN;
    216:       return(0);
    217:     }
    218:   } else {
    219:     fnorm               = snes->norm_init;
    220:     snes->norm_init_set = PETSC_FALSE;
    221:   }
    222:   fminnorm = fnorm;

    224:   /* q_{00} = nu  */
    225:   SNESNGMRESUpdateSubspace_Private(snes,0,0,F,fnorm,X);

    227:   PetscObjectAMSTakeAccess((PetscObject)snes);
    228:   snes->norm = fnorm;
    229:   PetscObjectAMSGrantAccess((PetscObject)snes);
    230:   SNESLogConvergenceHistory(snes,fnorm,0);
    231:   SNESMonitor(snes,0,fnorm);
    232:   (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);
    233:   if (snes->reason) return(0);

    235:   k_restart = 1;
    236:   l         = 1;
    237:   for (k=1; k < snes->max_its+1; k++) {
    238:     /* select which vector of the stored subspace will be updated */
    239:     ivec = k_restart % ngmres->msize; /* replace the last used part of the subspace */

    241:     /* Computation of x^M */
    242:     if (snes->pc && snes->pcside == PC_RIGHT) {
    243:       VecCopy(X,XM);
    244:       SNESSetInitialFunction(snes->pc,F);
    245:       SNESSetInitialFunctionNorm(snes->pc,fnorm);

    247:       PetscLogEventBegin(SNES_NPCSolve,snes->pc,XM,B,0);
    248:       SNESSolve(snes->pc,B,XM);
    249:       PetscLogEventEnd(SNES_NPCSolve,snes->pc,XM,B,0);

    251:       SNESGetConvergedReason(snes->pc,&reason);
    252:       if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
    253:         snes->reason = SNES_DIVERGED_INNER;
    254:         return(0);
    255:       }
    256:       SNESGetFunction(snes->pc,&FPC,NULL,NULL);
    257:       VecCopy(FPC,FM);
    258:       SNESGetFunctionNorm(snes->pc,&fMnorm);
    259:     } else {
    260:       /* no preconditioner -- just take gradient descent with line search */
    261:       VecCopy(F,Y);
    262:       VecCopy(F,FM);
    263:       VecCopy(X,XM);

    265:       fMnorm = fnorm;

    267:       SNESLineSearchApply(snes->linesearch,XM,FM,&fMnorm,Y);
    268:       SNESLineSearchGetSuccess(snes->linesearch,&lssucceed);
    269:       if (!lssucceed) {
    270:         if (++snes->numFailures >= snes->maxFailures) {
    271:           snes->reason = SNES_DIVERGED_LINE_SEARCH;
    272:           return(0);
    273:         }
    274:       }
    275:     }
    276:     SNESNGMRESFormCombinedSolution_Private(snes,l,XM,FM,fMnorm,X,XA,FA);
    277:     /* r = F(x) */
    278:     if (fminnorm > fMnorm) fminnorm = fMnorm;  /* the minimum norm is now of F^M */

    280:     /* differences for selection and restart */
    281:     if (ngmres->restart_type == SNES_NGMRES_RESTART_DIFFERENCE || ngmres->select_type == SNES_NGMRES_SELECT_DIFFERENCE) {
    282:       SNESNGMRESCalculateDifferences_Private(snes,l,X,F,XM,FM,XA,FA,D,&dnorm,&dminnorm,&fAnorm);
    283:     } else {
    284:       VecNorm(FA,NORM_2,&fAnorm);
    285:     }
    286:     if (PetscIsInfOrNanReal(fAnorm)) {
    287:       snes->reason = SNES_DIVERGED_FNORM_NAN;
    288:       return(0);
    289:     }

    291:     /* combination (additive) or selection (multiplicative) of the N-GMRES solution */
    292:     SNESNGMRESSelect_Private(snes,k_restart,XM,FM,fMnorm,XA,FA,fAnorm,dnorm,fminnorm,dminnorm,X,F,Y,&fnorm);
    293:     selectRestart = PETSC_FALSE;
    294:     if (ngmres->restart_type == SNES_NGMRES_RESTART_DIFFERENCE) {
    295:       SNESNGMRESSelectRestart_Private(snes,l,fAnorm,dnorm,fminnorm,dminnorm,&selectRestart);
    296:       /* if the restart conditions persist for more than restart_it iterations, restart. */
    297:       if (selectRestart) restart_count++;
    298:       else restart_count = 0;
    299:     } else if (ngmres->restart_type == SNES_NGMRES_RESTART_PERIODIC) {
    300:       if (k_restart > ngmres->restart_periodic) {
    301:         if (ngmres->monitor) PetscViewerASCIIPrintf(ngmres->monitor,"periodic restart after %D iterations\n",k_restart);
    302:         restart_count = ngmres->restart_it;
    303:       }
    304:     }
    305:     /* restart after restart conditions have persisted for a fixed number of iterations */
    306:     if (restart_count >= ngmres->restart_it) {
    307:       if (ngmres->monitor) {
    308:         PetscViewerASCIIPrintf(ngmres->monitor,"Restarted at iteration %d\n",k_restart);
    309:       }
    310:       restart_count = 0;
    311:       k_restart     = 1;
    312:       l             = 1;
    313:       /* q_{00} = nu */
    314:       if (ngmres->candidate) {
    315:         SNESNGMRESUpdateSubspace_Private(snes,0,0,FM,fMnorm,XM);
    316:       } else {
    317:         SNESNGMRESUpdateSubspace_Private(snes,0,0,F,fMnorm,X);
    318:       }
    319:     } else {
    320:       /* select the current size of the subspace */
    321:       if (l < ngmres->msize) l++;
    322:       k_restart++;
    323:       /* place the current entry in the list of previous entries */
    324:       if (ngmres->candidate) {
    325:         if (fminnorm > fMnorm) fminnorm = fMnorm;
    326:         SNESNGMRESUpdateSubspace_Private(snes,ivec,l,FM,fMnorm,XM);
    327:       } else {
    328:         if (fminnorm > fnorm) fminnorm = fnorm;
    329:         SNESNGMRESUpdateSubspace_Private(snes,ivec,l,F,fnorm,X);
    330:       }
    331:     }

    333:     PetscObjectAMSTakeAccess((PetscObject)snes);
    334:     snes->iter = k;
    335:     snes->norm = fnorm;
    336:     PetscObjectAMSGrantAccess((PetscObject)snes);
    337:     SNESLogConvergenceHistory(snes,snes->norm,snes->iter);
    338:     SNESMonitor(snes,snes->iter,snes->norm);
    339:     VecNormBegin(Y,NORM_2,&ynorm);
    340:     VecNormBegin(X,NORM_2,&xnorm);
    341:     VecNormEnd(Y,NORM_2,&ynorm);
    342:     VecNormEnd(X,NORM_2,&xnorm);
    343:     (*snes->ops->converged)(snes,snes->iter,xnorm,ynorm,fnorm,&snes->reason,snes->cnvP);
    344:     if (snes->reason) return(0);
    345:   }
    346:   snes->reason = SNES_DIVERGED_MAX_IT;
    347:   return(0);
    348: }

    352: /*@
    353:     SNESNGMRESSetRestartType - Sets the restart type for SNESNGMRES.

    355:     Logically Collective on SNES

    357:     Input Parameters:
    358: +   snes - the iterative context
    359: -   rtype - restart type

    361:     Options Database:
    362: +   -snes_ngmres_restart_type<difference,periodic,none> - set the restart type
    363: -   -snes_ngmres_restart[30] - sets the number of iterations before restart for periodic

    365:     Level: intermediate

    367:     SNESNGMRESRestartTypes:
    368: +   SNES_NGMRES_RESTART_NONE - never restart
    369: .   SNES_NGMRES_RESTART_DIFFERENCE - restart based upon difference criteria
    370: -   SNES_NGMRES_RESTART_PERIODIC - restart after a fixed number of iterations

    372:     Notes:
    373:     The default line search used is the L2 line search and it requires two additional function evaluations.

    375: .keywords: SNES, SNESNGMRES, restart, type, set SNESLineSearch
    376: @*/
    377: PetscErrorCode SNESNGMRESSetRestartType(SNES snes,SNESNGMRESRestartType rtype)
    378: {

    383:   PetscTryMethod(snes,"SNESNGMRESSetRestartType_C",(SNES,SNESNGMRESRestartType),(snes,rtype));
    384:   return(0);
    385: }

    389: /*@
    390:     SNESNGMRESSetSelectType - Sets the selection type for SNESNGMRES.  This determines how the candidate solution and
    391:     combined solution are used to create the next iterate.

    393:     Logically Collective on SNES

    395:     Input Parameters:
    396: +   snes - the iterative context
    397: -   stype - selection type

    399:     Options Database:
    400: .   -snes_ngmres_select_type<difference,none,linesearch>

    402:     Level: intermediate

    404:     SNESNGMRESSelectTypes:
    405: +   SNES_NGMRES_SELECT_NONE - choose the combined solution all the time
    406: .   SNES_NGMRES_SELECT_DIFFERENCE - choose based upon the selection criteria
    407: -   SNES_NGMRES_SELECT_LINESEARCH - choose based upon line search combination

    409:     Notes:
    410:     The default line search used is the L2 line search and it requires two additional function evaluations.

    412: .keywords: SNES, SNESNGMRES, selection, type, set SNESLineSearch
    413: @*/
    414: PetscErrorCode SNESNGMRESSetSelectType(SNES snes,SNESNGMRESSelectType stype)
    415: {

    420:   PetscTryMethod(snes,"SNESNGMRESSetSelectType_C",(SNES,SNESNGMRESSelectType),(snes,stype));
    421:   return(0);
    422: }

    426: PetscErrorCode SNESNGMRESSetSelectType_NGMRES(SNES snes,SNESNGMRESSelectType stype)
    427: {
    428:   SNES_NGMRES *ngmres = (SNES_NGMRES*)snes->data;

    431:   ngmres->select_type = stype;
    432:   return(0);
    433: }

    437: PetscErrorCode SNESNGMRESSetRestartType_NGMRES(SNES snes,SNESNGMRESRestartType rtype)
    438: {
    439:   SNES_NGMRES *ngmres = (SNES_NGMRES*)snes->data;

    442:   ngmres->restart_type = rtype;
    443:   return(0);
    444: }

    446: /*MC
    447:   SNESNGMRES - The Nonlinear Generalized Minimum Residual method.

    449:    Level: beginner

    451:    Options Database:
    452: +  -snes_ngmres_select_type<difference,none,linesearch> - choose the select between candidate and combined solution
    453: .  -snes_ngmres_restart_type<difference,none,periodic> - choose the restart conditions
    454: .  -snes_ngmres_candidate        - Use NGMRES variant which combines candidate solutions instead of actual solutions
    455: .  -snes_ngmres_m                - Number of stored previous solutions and residuals
    456: .  -snes_ngmres_restart_it       - Number of iterations the restart conditions hold before restart
    457: .  -snes_ngmres_gammaA           - Residual tolerance for solution select between the candidate and combination
    458: .  -snes_ngmres_gammaC           - Residual tolerance for restart
    459: .  -snes_ngmres_epsilonB         - Difference tolerance between subsequent solutions triggering restart
    460: .  -snes_ngmres_deltaB           - Difference tolerance between residuals triggering restart
    461: .  -snes_ngmres_monitor          - Prints relevant information about the ngmres iteration
    462: .  -snes_linesearch_type <basic,l2,cp> - Line search type used for the default smoother
    463: -  -additive_snes_linesearch_type - linesearch type used to select between the candidate and combined solution with additive select type

    465:    Notes:

    467:    The N-GMRES method combines m previous solutions into a minimum-residual solution by solving a small linearized
    468:    optimization problem at each iteration.

    470:    References:

    472:    "Krylov Subspace Acceleration of Nonlinear Multigrid with Application to Recirculating Flows", C. W. Oosterlee and T. Washio,
    473:    SIAM Journal on Scientific Computing, 21(5), 2000.

    475: .seealso: SNESCreate(), SNES, SNESSetType(), SNESType (for list of available types)
    476: M*/

    480: PETSC_EXTERN PetscErrorCode SNESCreate_NGMRES(SNES snes)
    481: {
    482:   SNES_NGMRES    *ngmres;

    486:   snes->ops->destroy        = SNESDestroy_NGMRES;
    487:   snes->ops->setup          = SNESSetUp_NGMRES;
    488:   snes->ops->setfromoptions = SNESSetFromOptions_NGMRES;
    489:   snes->ops->view           = SNESView_NGMRES;
    490:   snes->ops->solve          = SNESSolve_NGMRES;
    491:   snes->ops->reset          = SNESReset_NGMRES;

    493:   snes->usespc  = PETSC_TRUE;
    494:   snes->usesksp = PETSC_FALSE;

    496:   PetscNewLog(snes,SNES_NGMRES,&ngmres);
    497:   snes->data    = (void*) ngmres;
    498:   ngmres->msize = 30;

    500:   if (!snes->tolerancesset) {
    501:     snes->max_funcs = 30000;
    502:     snes->max_its   = 10000;
    503:   }

    505:   ngmres->candidate = PETSC_FALSE;

    507:   ngmres->additive_linesearch = NULL;
    508:   ngmres->approxfunc       = PETSC_FALSE;
    509:   ngmres->restart_it       = 2;
    510:   ngmres->restart_periodic = 30;
    511:   ngmres->gammaA           = 2.0;
    512:   ngmres->gammaC           = 2.0;
    513:   ngmres->deltaB           = 0.9;
    514:   ngmres->epsilonB         = 0.1;

    516:   ngmres->restart_type = SNES_NGMRES_RESTART_DIFFERENCE;
    517:   ngmres->select_type  = SNES_NGMRES_SELECT_DIFFERENCE;

    519:   PetscObjectComposeFunction((PetscObject)snes,"SNESNGMRESSetSelectType_C",SNESNGMRESSetSelectType_NGMRES);
    520:   PetscObjectComposeFunction((PetscObject)snes,"SNESNGMRESSetRestartType_C",SNESNGMRESSetRestartType_NGMRES);
    521:   return(0);
    522: }