Date: 2015-10-02T22:23:56+00:00

Actual source code: snesngmres.c
petsc-3.6.2 2015-10-02
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      1: #include <../src/snes/impls/ngmres/snesngmres.h> /*I "petscsnes.h" I*/
      2: #include <petscblaslapack.h>
      3: #include <petscdm.h>

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

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

     16:   VecDestroyVecs(ngmres->msize,&ngmres->Fdot);
     17:   VecDestroyVecs(ngmres->msize,&ngmres->Xdot);
     18:   SNESLineSearchDestroy(&ngmres->additive_linesearch);
     19:   return(0);
     20: }

     24: PetscErrorCode SNESDestroy_NGMRES(SNES snes)
     25: {
     27:   SNES_NGMRES    *ngmres = (SNES_NGMRES*)snes->data;

     30:   SNESReset_NGMRES(snes);
     31:   PetscFree5(ngmres->h,ngmres->beta,ngmres->xi,ngmres->fnorms,ngmres->q);
     32:   PetscFree(ngmres->s);
     33:   PetscFree(ngmres->xnorms);
     34: #if PETSC_USE_COMPLEX
     35:   PetscFree(ngmres->rwork);
     36: #endif
     37:   PetscFree(ngmres->work);
     38:   PetscFree(snes->data);
     39:   return(0);
     40: }

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

     53:   if (snes->pc && snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_UNPRECONDITIONED) {
     54:     SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE,"SNESNGMRES does not support left preconditioning with unpreconditioned function");
     55:   }
     56:   if (snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_DEFAULT) snes->functype = SNES_FUNCTION_PRECONDITIONED;
     57:   SNESSetWorkVecs(snes,5);

     59:   if (!snes->vec_sol) {
     60:     SNESGetDM(snes,&dm);
     61:     DMCreateGlobalVector(dm,&snes->vec_sol);
     62:   }

     64:   if (!ngmres->Xdot) {VecDuplicateVecs(snes->vec_sol,ngmres->msize,&ngmres->Xdot);}
     65:   if (!ngmres->Fdot) {VecDuplicateVecs(snes->vec_sol,ngmres->msize,&ngmres->Fdot);}
     66:   if (!ngmres->setup_called) {
     67:     msize = ngmres->msize;          /* restart size */
     68:     hsize = msize * msize;

     70:     /* explicit least squares minimization solve */
     71:     PetscMalloc5(hsize,&ngmres->h, msize,&ngmres->beta, msize,&ngmres->xi, msize,&ngmres->fnorms, hsize,&ngmres->q);
     72:     PetscMalloc1(msize,&ngmres->xnorms);
     73:     ngmres->nrhs  = 1;
     74:     ngmres->lda   = msize;
     75:     ngmres->ldb   = msize;
     76:     PetscMalloc1(msize,&ngmres->s);
     77:     PetscMemzero(ngmres->h,   hsize*sizeof(PetscScalar));
     78:     PetscMemzero(ngmres->q,   hsize*sizeof(PetscScalar));
     79:     PetscMemzero(ngmres->xi,  msize*sizeof(PetscScalar));
     80:     PetscMemzero(ngmres->beta,msize*sizeof(PetscScalar));
     81:     ngmres->lwork = 12*msize;
     82: #if PETSC_USE_COMPLEX
     83:     PetscMalloc1(ngmres->lwork,&ngmres->rwork);
     84: #endif
     85:     PetscMalloc1(ngmres->lwork,&ngmres->work);
     86:   }

     88:   /* linesearch setup */
     89:   SNESGetOptionsPrefix(snes,&optionsprefix);

     91:   if (ngmres->select_type == SNES_NGMRES_SELECT_LINESEARCH) {
     92:     SNESLineSearchCreate(PetscObjectComm((PetscObject)snes),&ngmres->additive_linesearch);
     93:     SNESLineSearchSetSNES(ngmres->additive_linesearch,snes);
     94:     SNESLineSearchSetType(ngmres->additive_linesearch,SNESLINESEARCHL2);
     95:     SNESLineSearchAppendOptionsPrefix(ngmres->additive_linesearch,"additive_");
     96:     SNESLineSearchAppendOptionsPrefix(ngmres->additive_linesearch,optionsprefix);
     97:     SNESLineSearchSetFromOptions(ngmres->additive_linesearch);
     98:   }

    100:   ngmres->setup_called = PETSC_TRUE;
    101:   return(0);
    102: }

    106: PetscErrorCode SNESSetFromOptions_NGMRES(PetscOptions *PetscOptionsObject,SNES snes)
    107: {
    108:   SNES_NGMRES    *ngmres = (SNES_NGMRES*) snes->data;
    110:   PetscBool      debug = PETSC_FALSE;
    111:   SNESLineSearch linesearch;

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

    136:   /* set the default type of the line search if the user hasn't already. */
    137:   if (!snes->linesearch) {
    138:     SNESGetLineSearch(snes,&linesearch);
    139:     SNESLineSearchSetType(linesearch,SNESLINESEARCHBASIC);
    140:   }
    141:   return(0);
    142: }

    146: PetscErrorCode SNESView_NGMRES(SNES snes,PetscViewer viewer)
    147: {
    148:   SNES_NGMRES    *ngmres = (SNES_NGMRES*) snes->data;
    149:   PetscBool      iascii;

    153:   PetscObjectTypeCompare((PetscObject) viewer,PETSCVIEWERASCII,&iascii);
    154:   if (iascii) {
    155:     PetscViewerASCIIPrintf(viewer,"  Number of stored past updates: %d\n", ngmres->msize);
    156:     PetscViewerASCIIPrintf(viewer,"  Residual selection: gammaA=%1.0e, gammaC=%1.0e\n",ngmres->gammaA,ngmres->gammaC);
    157:     PetscViewerASCIIPrintf(viewer,"  Difference restart: epsilonB=%1.0e, deltaB=%1.0e\n",ngmres->epsilonB,ngmres->deltaB);
    158:   }
    159:   return(0);
    160: }

    164: PetscErrorCode SNESSolve_NGMRES(SNES snes)
    165: {
    166:   SNES_NGMRES          *ngmres = (SNES_NGMRES*) snes->data;
    167:   /* present solution, residual, and preconditioned residual */
    168:   Vec                  X,F,B,D,Y;

    170:   /* candidate linear combination answers */
    171:   Vec                  XA,FA,XM,FM;

    173:   /* coefficients and RHS to the minimization problem */
    174:   PetscReal            fnorm,fMnorm,fAnorm;
    175:   PetscReal            xnorm,xMnorm,xAnorm;
    176:   PetscReal            ynorm,yMnorm,yAnorm;
    177:   PetscInt             k,k_restart,l,ivec,restart_count = 0;

    179:   /* solution selection data */
    180:   PetscBool            selectRestart;
    181:   PetscReal            dnorm,dminnorm = 0.0;
    182:   PetscReal            fminnorm;

    184:   SNESConvergedReason  reason;
    185:   SNESLineSearchReason lssucceed;
    186:   PetscErrorCode       ierr;

    190:   if (snes->xl || snes->xu || snes->ops->computevariablebounds) {
    191:     SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONGSTATE, "SNES solver %s does not support bounds", ((PetscObject)snes)->type_name);
    192:   }

    194:   PetscCitationsRegister(SNESCitation,&SNEScite);
    195:   /* variable initialization */
    196:   snes->reason = SNES_CONVERGED_ITERATING;
    197:   X            = snes->vec_sol;
    198:   F            = snes->vec_func;
    199:   B            = snes->vec_rhs;
    200:   XA           = snes->vec_sol_update;
    201:   FA           = snes->work[0];
    202:   D            = snes->work[1];

    204:   /* work for the line search */
    205:   Y  = snes->work[2];
    206:   XM = snes->work[3];
    207:   FM = snes->work[4];

    209:   PetscObjectSAWsTakeAccess((PetscObject)snes);
    210:   snes->iter = 0;
    211:   snes->norm = 0.;
    212:   PetscObjectSAWsGrantAccess((PetscObject)snes);

    214:   /* initialization */

    216:   if (snes->pc && snes->pcside == PC_LEFT) {
    217:     SNESApplyNPC(snes,X,NULL,F);
    218:     SNESGetConvergedReason(snes->pc,&reason);
    219:     if (reason < 0  && reason != SNES_DIVERGED_MAX_IT) {
    220:       snes->reason = SNES_DIVERGED_INNER;
    221:       return(0);
    222:     }
    223:     VecNorm(F,NORM_2,&fnorm);
    224:   } else {
    225:     if (!snes->vec_func_init_set) {
    226:       SNESComputeFunction(snes,X,F);
    227:     } else snes->vec_func_init_set = PETSC_FALSE;

    229:     VecNorm(F,NORM_2,&fnorm);
    230:     SNESCheckFunctionNorm(snes,fnorm);
    231:   }
    232:   fminnorm = fnorm;

    234:   PetscObjectSAWsTakeAccess((PetscObject)snes);
    235:   snes->norm = fnorm;
    236:   PetscObjectSAWsGrantAccess((PetscObject)snes);
    237:   SNESLogConvergenceHistory(snes,fnorm,0);
    238:   SNESMonitor(snes,0,fnorm);
    239:   (*snes->ops->converged)(snes,0,0.0,0.0,fnorm,&snes->reason,snes->cnvP);
    240:   if (snes->reason) return(0);
    241:   SNESNGMRESUpdateSubspace_Private(snes,0,0,F,fnorm,X);

    243:   k_restart = 1;
    244:   l         = 1;
    245:   ivec      = 0;
    246:   for (k=1; k < snes->max_its+1; k++) {
    247:     /* Computation of x^M */
    248:     if (snes->pc && snes->pcside == PC_RIGHT) {
    249:       VecCopy(X,XM);
    250:       SNESSetInitialFunction(snes->pc,F);

    252:       PetscLogEventBegin(SNES_NPCSolve,snes->pc,XM,B,0);
    253:       SNESSolve(snes->pc,B,XM);
    254:       PetscLogEventEnd(SNES_NPCSolve,snes->pc,XM,B,0);

    256:       SNESGetConvergedReason(snes->pc,&reason);
    257:       if (reason < 0 && reason != SNES_DIVERGED_MAX_IT) {
    258:         snes->reason = SNES_DIVERGED_INNER;
    259:         return(0);
    260:       }
    261:       SNESGetNPCFunction(snes,FM,&fMnorm);
    262:     } else {
    263:       /* no preconditioner -- just take gradient descent with line search */
    264:       VecCopy(F,Y);
    265:       VecCopy(F,FM);
    266:       VecCopy(X,XM);

    268:       fMnorm = fnorm;

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

    283:     /* differences for selection and restart */
    284:     if (ngmres->restart_type == SNES_NGMRES_RESTART_DIFFERENCE || ngmres->select_type == SNES_NGMRES_SELECT_DIFFERENCE) {
    285:       SNESNGMRESNorms_Private(snes,l,X,F,XM,FM,XA,FA,D,&dnorm,&dminnorm,&xMnorm,NULL,&yMnorm,&xAnorm,&fAnorm,&yAnorm);
    286:     } else {
    287:       SNESNGMRESNorms_Private(snes,l,X,F,XM,FM,XA,FA,D,NULL,NULL,&xMnorm,NULL,&yMnorm,&xAnorm,&fAnorm,&yAnorm);
    288:     }
    289:     SNESCheckFunctionNorm(snes,fnorm);

    291:     /* combination (additive) or selection (multiplicative) of the N-GMRES solution */
    292:     SNESNGMRESSelect_Private(snes,k_restart,XM,FM,xMnorm,fMnorm,yMnorm,XA,FA,xAnorm,fAnorm,yAnorm,dnorm,fminnorm,dminnorm,X,F,Y,&xnorm,&fnorm,&ynorm);
    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:     ivec = k_restart % ngmres->msize; /* replace the last used part of the subspace */
    306:     /* restart after restart conditions have persisted for a fixed number of iterations */
    307:     if (restart_count >= ngmres->restart_it) {
    308:       if (ngmres->monitor) {
    309:         PetscViewerASCIIPrintf(ngmres->monitor,"Restarted at iteration %d\n",k_restart);
    310:       }
    311:       restart_count = 0;
    312:       k_restart     = 1;
    313:       l             = 1;
    314:       ivec          = 0;
    315:       /* q_{00} = nu */
    316:       SNESNGMRESUpdateSubspace_Private(snes,0,0,FM,fMnorm,XM);
    317:     } else {
    318:       /* select the current size of the subspace */
    319:       if (l < ngmres->msize) l++;
    320:       k_restart++;
    321:       /* place the current entry in the list of previous entries */
    322:       if (ngmres->candidate) {
    323:         if (fminnorm > fMnorm) fminnorm = fMnorm;
    324:         SNESNGMRESUpdateSubspace_Private(snes,ivec,l,FM,fMnorm,XM);
    325:       } else {
    326:         if (fminnorm > fnorm) fminnorm = fnorm;
    327:         SNESNGMRESUpdateSubspace_Private(snes,ivec,l,F,fnorm,X);
    328:       }
    329:     }

    331:     PetscObjectSAWsTakeAccess((PetscObject)snes);
    332:     snes->iter = k;
    333:     snes->norm = fnorm;
    334:     PetscObjectSAWsGrantAccess((PetscObject)snes);
    335:     SNESLogConvergenceHistory(snes,snes->norm,snes->iter);
    336:     SNESMonitor(snes,snes->iter,snes->norm);
    337:     (*snes->ops->converged)(snes,snes->iter,0,0,fnorm,&snes->reason,snes->cnvP);
    338:     if (snes->reason) return(0);
    339:   }
    340:   snes->reason = SNES_DIVERGED_MAX_IT;
    341:   return(0);
    342: }

    346: /*@
    347:     SNESNGMRESSetRestartType - Sets the restart type for SNESNGMRES.

    349:     Logically Collective on SNES

    351:     Input Parameters:
    352: +   snes - the iterative context
    353: -   rtype - restart type

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

    359:     Level: intermediate

    361:     SNESNGMRESRestartTypes:
    362: +   SNES_NGMRES_RESTART_NONE - never restart
    363: .   SNES_NGMRES_RESTART_DIFFERENCE - restart based upon difference criteria
    364: -   SNES_NGMRES_RESTART_PERIODIC - restart after a fixed number of iterations

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

    369: .keywords: SNES, SNESNGMRES, restart, type, set SNESLineSearch
    370: @*/
    371: PetscErrorCode SNESNGMRESSetRestartType(SNES snes,SNESNGMRESRestartType rtype)
    372: {

    377:   PetscTryMethod(snes,"SNESNGMRESSetRestartType_C",(SNES,SNESNGMRESRestartType),(snes,rtype));
    378:   return(0);
    379: }

    383: /*@
    384:     SNESNGMRESSetSelectType - Sets the selection type for SNESNGMRES.  This determines how the candidate solution and
    385:     combined solution are used to create the next iterate.

    387:     Logically Collective on SNES

    389:     Input Parameters:
    390: +   snes - the iterative context
    391: -   stype - selection type

    393:     Options Database:
    394: .   -snes_ngmres_select_type<difference,none,linesearch>

    396:     Level: intermediate

    398:     SNESNGMRESSelectTypes:
    399: +   SNES_NGMRES_SELECT_NONE - choose the combined solution all the time
    400: .   SNES_NGMRES_SELECT_DIFFERENCE - choose based upon the selection criteria
    401: -   SNES_NGMRES_SELECT_LINESEARCH - choose based upon line search combination

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

    406: .keywords: SNES, SNESNGMRES, selection, type, set SNESLineSearch
    407: @*/
    408: PetscErrorCode SNESNGMRESSetSelectType(SNES snes,SNESNGMRESSelectType stype)
    409: {

    414:   PetscTryMethod(snes,"SNESNGMRESSetSelectType_C",(SNES,SNESNGMRESSelectType),(snes,stype));
    415:   return(0);
    416: }

    420: PetscErrorCode SNESNGMRESSetSelectType_NGMRES(SNES snes,SNESNGMRESSelectType stype)
    421: {
    422:   SNES_NGMRES *ngmres = (SNES_NGMRES*)snes->data;

    425:   ngmres->select_type = stype;
    426:   return(0);
    427: }

    431: PetscErrorCode SNESNGMRESSetRestartType_NGMRES(SNES snes,SNESNGMRESRestartType rtype)
    432: {
    433:   SNES_NGMRES *ngmres = (SNES_NGMRES*)snes->data;

    436:   ngmres->restart_type = rtype;
    437:   return(0);
    438: }

    440: /*MC
    441:   SNESNGMRES - The Nonlinear Generalized Minimum Residual method.

    443:    Level: beginner

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

    459:    Notes:

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

    464:    References:

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

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

    474: PETSC_EXTERN PetscErrorCode SNESCreate_NGMRES(SNES snes)
    475: {
    476:   SNES_NGMRES    *ngmres;

    480:   snes->ops->destroy        = SNESDestroy_NGMRES;
    481:   snes->ops->setup          = SNESSetUp_NGMRES;
    482:   snes->ops->setfromoptions = SNESSetFromOptions_NGMRES;
    483:   snes->ops->view           = SNESView_NGMRES;
    484:   snes->ops->solve          = SNESSolve_NGMRES;
    485:   snes->ops->reset          = SNESReset_NGMRES;

    487:   snes->usespc   = PETSC_TRUE;
    488:   snes->usesksp  = PETSC_FALSE;
    489:   snes->pcside   = PC_RIGHT;

    491:   PetscNewLog(snes,&ngmres);
    492:   snes->data    = (void*) ngmres;
    493:   ngmres->msize = 30;

    495:   if (!snes->tolerancesset) {
    496:     snes->max_funcs = 30000;
    497:     snes->max_its   = 10000;
    498:   }

    500:   ngmres->candidate = PETSC_FALSE;

    502:   ngmres->additive_linesearch = NULL;
    503:   ngmres->approxfunc       = PETSC_FALSE;
    504:   ngmres->restart_it       = 2;
    505:   ngmres->restart_periodic = 30;
    506:   ngmres->gammaA           = 2.0;
    507:   ngmres->gammaC           = 2.0;
    508:   ngmres->deltaB           = 0.9;
    509:   ngmres->epsilonB         = 0.1;

    511:   ngmres->restart_type = SNES_NGMRES_RESTART_DIFFERENCE;
    512:   ngmres->select_type  = SNES_NGMRES_SELECT_DIFFERENCE;

    514:   PetscObjectComposeFunction((PetscObject)snes,"SNESNGMRESSetSelectType_C",SNESNGMRESSetSelectType_NGMRES);
    515:   PetscObjectComposeFunction((PetscObject)snes,"SNESNGMRESSetRestartType_C",SNESNGMRESSetRestartType_NGMRES);
    516:   return(0);
    517: }