Date: 2016-07-24T17:08:40+00:00

Actual source code: snes.c
petsc-3.7.3 2016-07-24
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      2: #include <petsc/private/snesimpl.h>      /*I "petscsnes.h"  I*/
      3: #include <petscdmshell.h>
      4: #include <petscdraw.h>

      6: PetscBool         SNESRegisterAllCalled = PETSC_FALSE;
      7: PetscFunctionList SNESList              = NULL;

      9: /* Logging support */
     10: PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
     11: PetscLogEvent SNES_Solve, SNES_FunctionEval, SNES_JacobianEval, SNES_NGSEval, SNES_NGSFuncEval, SNES_NPCSolve, SNES_ObjectiveEval;

     15: /*@
     16:    SNESSetErrorIfNotConverged - Causes SNESSolve() to generate an error if the solver has not converged.

     18:    Logically Collective on SNES

     20:    Input Parameters:
     21: +  snes - iterative context obtained from SNESCreate()
     22: -  flg - PETSC_TRUE indicates you want the error generated

     24:    Options database keys:
     25: .  -snes_error_if_not_converged : this takes an optional truth value (0/1/no/yes/true/false)

     27:    Level: intermediate

     29:    Notes:
     30:     Normally PETSc continues if a linear solver fails to converge, you can call SNESGetConvergedReason() after a SNESSolve()
     31:     to determine if it has converged.

     33: .keywords: SNES, set, initial guess, nonzero

     35: .seealso: SNESGetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
     36: @*/
     37: PetscErrorCode  SNESSetErrorIfNotConverged(SNES snes,PetscBool flg)
     38: {
     42:   snes->errorifnotconverged = flg;
     43:   return(0);
     44: }

     48: /*@
     49:    SNESGetErrorIfNotConverged - Will SNESSolve() generate an error if the solver does not converge?

     51:    Not Collective

     53:    Input Parameter:
     54: .  snes - iterative context obtained from SNESCreate()

     56:    Output Parameter:
     57: .  flag - PETSC_TRUE if it will generate an error, else PETSC_FALSE

     59:    Level: intermediate

     61: .keywords: SNES, set, initial guess, nonzero

     63: .seealso:  SNESSetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
     64: @*/
     65: PetscErrorCode  SNESGetErrorIfNotConverged(SNES snes,PetscBool  *flag)
     66: {
     70:   *flag = snes->errorifnotconverged;
     71:   return(0);
     72: }

     76: /*@
     77:    SNESSetFunctionDomainError - tells SNES that the input vector to your SNESFunction is not
     78:      in the functions domain. For example, negative pressure.

     80:    Logically Collective on SNES

     82:    Input Parameters:
     83: .  snes - the SNES context

     85:    Level: advanced

     87: .keywords: SNES, view

     89: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction
     90: @*/
     91: PetscErrorCode  SNESSetFunctionDomainError(SNES snes)
     92: {
     95:   if (snes->errorifnotconverged) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"User code indicates input vector is not in the function domain");
     96:   snes->domainerror = PETSC_TRUE;
     97:   return(0);
     98: }

    102: /*@
    103:    SNESGetFunctionDomainError - Gets the status of the domain error after a call to SNESComputeFunction;

    105:    Logically Collective on SNES

    107:    Input Parameters:
    108: .  snes - the SNES context

    110:    Output Parameters:
    111: .  domainerror - Set to PETSC_TRUE if there's a domain error; PETSC_FALSE otherwise.

    113:    Level: advanced

    115: .keywords: SNES, view

    117: .seealso: SNESSetFunctionDomainError(), SNESComputeFunction()
    118: @*/
    119: PetscErrorCode  SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
    120: {
    124:   *domainerror = snes->domainerror;
    125:   return(0);
    126: }

    130: /*@C
    131:   SNESLoad - Loads a SNES that has been stored in binary  with SNESView().

    133:   Collective on PetscViewer

    135:   Input Parameters:
    136: + newdm - the newly loaded SNES, this needs to have been created with SNESCreate() or
    137:            some related function before a call to SNESLoad().
    138: - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()

    140:    Level: intermediate

    142:   Notes:
    143:    The type is determined by the data in the file, any type set into the SNES before this call is ignored.

    145:   Notes for advanced users:
    146:   Most users should not need to know the details of the binary storage
    147:   format, since SNESLoad() and TSView() completely hide these details.
    148:   But for anyone who's interested, the standard binary matrix storage
    149:   format is
    150: .vb
    151:      has not yet been determined
    152: .ve

    154: .seealso: PetscViewerBinaryOpen(), SNESView(), MatLoad(), VecLoad()
    155: @*/
    156: PetscErrorCode  SNESLoad(SNES snes, PetscViewer viewer)
    157: {
    159:   PetscBool      isbinary;
    160:   PetscInt       classid;
    161:   char           type[256];
    162:   KSP            ksp;
    163:   DM             dm;
    164:   DMSNES         dmsnes;

    169:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
    170:   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");

    172:   PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);
    173:   if (classid != SNES_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONG,"Not SNES next in file");
    174:   PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);
    175:   SNESSetType(snes, type);
    176:   if (snes->ops->load) {
    177:     (*snes->ops->load)(snes,viewer);
    178:   }
    179:   SNESGetDM(snes,&dm);
    180:   DMGetDMSNES(dm,&dmsnes);
    181:   DMSNESLoad(dmsnes,viewer);
    182:   SNESGetKSP(snes,&ksp);
    183:   KSPLoad(ksp,viewer);
    184:   return(0);
    185: }

    187: #include <petscdraw.h>
    188: #if defined(PETSC_HAVE_SAWS)
    189: #include <petscviewersaws.h>
    190: #endif
    193: /*@C
    194:    SNESView - Prints the SNES data structure.

    196:    Collective on SNES

    198:    Input Parameters:
    199: +  SNES - the SNES context
    200: -  viewer - visualization context

    202:    Options Database Key:
    203: .  -snes_view - Calls SNESView() at end of SNESSolve()

    205:    Notes:
    206:    The available visualization contexts include
    207: +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
    208: -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
    209:          output where only the first processor opens
    210:          the file.  All other processors send their
    211:          data to the first processor to print.

    213:    The user can open an alternative visualization context with
    214:    PetscViewerASCIIOpen() - output to a specified file.

    216:    Level: beginner

    218: .keywords: SNES, view

    220: .seealso: PetscViewerASCIIOpen()
    221: @*/
    222: PetscErrorCode  SNESView(SNES snes,PetscViewer viewer)
    223: {
    224:   SNESKSPEW      *kctx;
    226:   KSP            ksp;
    227:   SNESLineSearch linesearch;
    228:   PetscBool      iascii,isstring,isbinary,isdraw;
    229:   DMSNES         dmsnes;
    230: #if defined(PETSC_HAVE_SAWS)
    231:   PetscBool      issaws;
    232: #endif

    236:   if (!viewer) {
    237:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&viewer);
    238:   }

    242:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
    243:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);
    244:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
    245:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
    246: #if defined(PETSC_HAVE_SAWS)
    247:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);
    248: #endif
    249:   if (iascii) {
    250:     SNESNormSchedule normschedule;

    252:     PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer);
    253:     if (!snes->setupcalled) {
    254:       PetscViewerASCIIPrintf(viewer,"  SNES has not been set up so information may be incomplete\n");
    255:     }
    256:     if (snes->ops->view) {
    257:       PetscViewerASCIIPushTab(viewer);
    258:       (*snes->ops->view)(snes,viewer);
    259:       PetscViewerASCIIPopTab(viewer);
    260:     }
    261:     PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);
    262:     PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%g, absolute=%g, solution=%g\n",(double)snes->rtol,(double)snes->abstol,(double)snes->stol);
    263:     PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);
    264:     PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);
    265:     SNESGetNormSchedule(snes, &normschedule);
    266:     if (normschedule > 0) {PetscViewerASCIIPrintf(viewer,"  norm schedule %s\n",SNESNormSchedules[normschedule]);}
    267:     if (snes->gridsequence) {
    268:       PetscViewerASCIIPrintf(viewer,"  total number of grid sequence refinements=%D\n",snes->gridsequence);
    269:     }
    270:     if (snes->ksp_ewconv) {
    271:       kctx = (SNESKSPEW*)snes->kspconvctx;
    272:       if (kctx) {
    273:         PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);
    274:         PetscViewerASCIIPrintf(viewer,"    rtol_0=%g, rtol_max=%g, threshold=%g\n",(double)kctx->rtol_0,(double)kctx->rtol_max,(double)kctx->threshold);
    275:         PetscViewerASCIIPrintf(viewer,"    gamma=%g, alpha=%g, alpha2=%g\n",(double)kctx->gamma,(double)kctx->alpha,(double)kctx->alpha2);
    276:       }
    277:     }
    278:     if (snes->lagpreconditioner == -1) {
    279:       PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");
    280:     } else if (snes->lagpreconditioner > 1) {
    281:       PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);
    282:     }
    283:     if (snes->lagjacobian == -1) {
    284:       PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");
    285:     } else if (snes->lagjacobian > 1) {
    286:       PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);
    287:     }
    288:   } else if (isstring) {
    289:     const char *type;
    290:     SNESGetType(snes,&type);
    291:     PetscViewerStringSPrintf(viewer," %-3.3s",type);
    292:   } else if (isbinary) {
    293:     PetscInt    classid = SNES_FILE_CLASSID;
    294:     MPI_Comm    comm;
    295:     PetscMPIInt rank;
    296:     char        type[256];

    298:     PetscObjectGetComm((PetscObject)snes,&comm);
    299:     MPI_Comm_rank(comm,&rank);
    300:     if (!rank) {
    301:       PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);
    302:       PetscStrncpy(type,((PetscObject)snes)->type_name,sizeof(type));
    303:       PetscViewerBinaryWrite(viewer,type,sizeof(type),PETSC_CHAR,PETSC_FALSE);
    304:     }
    305:     if (snes->ops->view) {
    306:       (*snes->ops->view)(snes,viewer);
    307:     }
    308:   } else if (isdraw) {
    309:     PetscDraw draw;
    310:     char      str[36];
    311:     PetscReal x,y,bottom,h;

    313:     PetscViewerDrawGetDraw(viewer,0,&draw);
    314:     PetscDrawGetCurrentPoint(draw,&x,&y);
    315:     PetscStrcpy(str,"SNES: ");
    316:     PetscStrcat(str,((PetscObject)snes)->type_name);
    317:     PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_BLUE,PETSC_DRAW_BLACK,str,NULL,&h);
    318:     bottom = y - h;
    319:     PetscDrawPushCurrentPoint(draw,x,bottom);
    320:     if (snes->ops->view) {
    321:       (*snes->ops->view)(snes,viewer);
    322:     }
    323: #if defined(PETSC_HAVE_SAWS)
    324:   } else if (issaws) {
    325:     PetscMPIInt rank;
    326:     const char *name;

    328:     PetscObjectGetName((PetscObject)snes,&name);
    329:     MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
    330:     if (!((PetscObject)snes)->amsmem && !rank) {
    331:       char       dir[1024];

    333:       PetscObjectViewSAWs((PetscObject)snes,viewer);
    334:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);
    335:       PetscStackCallSAWs(SAWs_Register,(dir,&snes->iter,1,SAWs_READ,SAWs_INT));
    336:       if (!snes->conv_hist) {
    337:         SNESSetConvergenceHistory(snes,NULL,NULL,PETSC_DECIDE,PETSC_TRUE);
    338:       }
    339:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/conv_hist",name);
    340:       PetscStackCallSAWs(SAWs_Register,(dir,snes->conv_hist,10,SAWs_READ,SAWs_DOUBLE));
    341:     }
    342: #endif
    343:   }
    344:   if (snes->linesearch) {
    345:     PetscViewerASCIIPushTab(viewer);
    346:     SNESGetLineSearch(snes, &linesearch);
    347:     SNESLineSearchView(linesearch, viewer);
    348:     PetscViewerASCIIPopTab(viewer);
    349:   }
    350:   if (snes->pc && snes->usespc) {
    351:     PetscViewerASCIIPushTab(viewer);
    352:     SNESView(snes->pc, viewer);
    353:     PetscViewerASCIIPopTab(viewer);
    354:   }
    355:   PetscViewerASCIIPushTab(viewer);
    356:   DMGetDMSNES(snes->dm,&dmsnes);
    357:   DMSNESView(dmsnes, viewer);
    358:   PetscViewerASCIIPopTab(viewer);
    359:   if (snes->usesksp) {
    360:     SNESGetKSP(snes,&ksp);
    361:     PetscViewerASCIIPushTab(viewer);
    362:     KSPView(ksp,viewer);
    363:     PetscViewerASCIIPopTab(viewer);
    364:   }
    365:   if (isdraw) {
    366:     PetscDraw draw;
    367:     PetscViewerDrawGetDraw(viewer,0,&draw);
    368:     PetscDrawPopCurrentPoint(draw);
    369:   }
    370:   return(0);
    371: }

    373: /*
    374:   We retain a list of functions that also take SNES command
    375:   line options. These are called at the end SNESSetFromOptions()
    376: */
    377: #define MAXSETFROMOPTIONS 5
    378: static PetscInt numberofsetfromoptions;
    379: static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);

    383: /*@C
    384:   SNESAddOptionsChecker - Adds an additional function to check for SNES options.

    386:   Not Collective

    388:   Input Parameter:
    389: . snescheck - function that checks for options

    391:   Level: developer

    393: .seealso: SNESSetFromOptions()
    394: @*/
    395: PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
    396: {
    398:   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
    399:   othersetfromoptions[numberofsetfromoptions++] = snescheck;
    400:   return(0);
    401: }

    403: extern PetscErrorCode  SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);

    407: static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
    408: {
    409:   Mat            J;
    410:   KSP            ksp;
    411:   PC             pc;
    412:   PetscBool      match;
    414:   MatNullSpace   nullsp;

    419:   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
    420:     Mat A = snes->jacobian, B = snes->jacobian_pre;
    421:     MatCreateVecs(A ? A : B, NULL,&snes->vec_func);
    422:   }

    424:   if (version == 1) {
    425:     MatCreateSNESMF(snes,&J);
    426:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
    427:     MatSetFromOptions(J);
    428:   } else if (version == 2) {
    429:     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
    430: #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128)
    431:     SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);
    432: #else
    433:     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator rutines (version 2)");
    434: #endif
    435:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator rutines, only version 1 and 2");

    437:   /* attach any user provided null space that was on Amat to the newly created matrix free matrix */
    438:   if (snes->jacobian) {
    439:     MatGetNullSpace(snes->jacobian,&nullsp);
    440:     if (nullsp) {
    441:       MatSetNullSpace(J,nullsp);
    442:     }
    443:   }

    445:   PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);
    446:   if (hasOperator) {

    448:     /* This version replaces the user provided Jacobian matrix with a
    449:        matrix-free version but still employs the user-provided preconditioner matrix. */
    450:     SNESSetJacobian(snes,J,0,0,0);
    451:   } else {
    452:     /* This version replaces both the user-provided Jacobian and the user-
    453:      provided preconditioner Jacobian with the default matrix free version. */
    454:     if ((snes->pcside == PC_LEFT) && snes->pc) {
    455:       if (!snes->jacobian){SNESSetJacobian(snes,J,0,0,0);}
    456:     } else {
    457:       SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,0);
    458:     }
    459:     /* Force no preconditioner */
    460:     SNESGetKSP(snes,&ksp);
    461:     KSPGetPC(ksp,&pc);
    462:     PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);
    463:     if (!match) {
    464:       PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");
    465:       PCSetType(pc,PCNONE);
    466:     }
    467:   }
    468:   MatDestroy(&J);
    469:   return(0);
    470: }

    474: static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
    475: {
    476:   SNES           snes = (SNES)ctx;
    478:   Vec            Xfine,Xfine_named = NULL,Xcoarse;

    481:   if (PetscLogPrintInfo) {
    482:     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
    483:     DMGetRefineLevel(dmfine,&finelevel);
    484:     DMGetCoarsenLevel(dmfine,&fineclevel);
    485:     DMGetRefineLevel(dmcoarse,&coarselevel);
    486:     DMGetCoarsenLevel(dmcoarse,&coarseclevel);
    487:     PetscInfo4(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);
    488:   }
    489:   if (dmfine == snes->dm) Xfine = snes->vec_sol;
    490:   else {
    491:     DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);
    492:     Xfine = Xfine_named;
    493:   }
    494:   DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);
    495:   if (Inject) {
    496:     MatRestrict(Inject,Xfine,Xcoarse);
    497:   } else {
    498:     MatRestrict(Restrict,Xfine,Xcoarse);
    499:     VecPointwiseMult(Xcoarse,Xcoarse,Rscale);
    500:   }
    501:   DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);
    502:   if (Xfine_named) {DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);}
    503:   return(0);
    504: }

    508: static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
    509: {

    513:   DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);
    514:   return(0);
    515: }

    519: /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
    520:  * safely call SNESGetDM() in their residual evaluation routine. */
    521: static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,void *ctx)
    522: {
    523:   SNES           snes = (SNES)ctx;
    525:   Mat            Asave = A,Bsave = B;
    526:   Vec            X,Xnamed = NULL;
    527:   DM             dmsave;
    528:   void           *ctxsave;
    529:   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);

    532:   dmsave = snes->dm;
    533:   KSPGetDM(ksp,&snes->dm);
    534:   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
    535:   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
    536:     DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);
    537:     X    = Xnamed;
    538:     SNESGetJacobian(snes,NULL,NULL,&jac,&ctxsave);
    539:     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
    540:     if (jac == SNESComputeJacobianDefaultColor) {
    541:       SNESSetJacobian(snes,NULL,NULL,SNESComputeJacobianDefaultColor,0);
    542:     }
    543:   }
    544:   /* put the previous context back */

    546:   SNESComputeJacobian(snes,X,A,B);
    547:   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) {
    548:     SNESSetJacobian(snes,NULL,NULL,jac,ctxsave);
    549:   }

    551:   if (A != Asave || B != Bsave) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_SUP,"No support for changing matrices at this time");
    552:   if (Xnamed) {
    553:     DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);
    554:   }
    555:   snes->dm = dmsave;
    556:   return(0);
    557: }

    561: /*@
    562:    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()

    564:    Collective

    566:    Input Arguments:
    567: .  snes - snes to configure

    569:    Level: developer

    571: .seealso: SNESSetUp()
    572: @*/
    573: PetscErrorCode SNESSetUpMatrices(SNES snes)
    574: {
    576:   DM             dm;
    577:   DMSNES         sdm;

    580:   SNESGetDM(snes,&dm);
    581:   DMGetDMSNES(dm,&sdm);
    582:   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_PLIB,"DMSNES not properly configured");
    583:   else if (!snes->jacobian && snes->mf) {
    584:     Mat  J;
    585:     void *functx;
    586:     MatCreateSNESMF(snes,&J);
    587:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
    588:     MatSetFromOptions(J);
    589:     SNESGetFunction(snes,NULL,NULL,&functx);
    590:     SNESSetJacobian(snes,J,J,0,0);
    591:     MatDestroy(&J);
    592:   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
    593:     Mat J,B;
    594:     MatCreateSNESMF(snes,&J);
    595:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
    596:     MatSetFromOptions(J);
    597:     DMCreateMatrix(snes->dm,&B);
    598:     /* sdm->computejacobian was already set to reach here */
    599:     SNESSetJacobian(snes,J,B,NULL,NULL);
    600:     MatDestroy(&J);
    601:     MatDestroy(&B);
    602:   } else if (!snes->jacobian_pre) {
    603:     Mat J,B;
    604:     J    = snes->jacobian;
    605:     DMCreateMatrix(snes->dm,&B);
    606:     SNESSetJacobian(snes,J ? J : B,B,NULL,NULL);
    607:     MatDestroy(&B);
    608:   }
    609:   {
    610:     KSP ksp;
    611:     SNESGetKSP(snes,&ksp);
    612:     KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);
    613:     DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);
    614:   }
    615:   return(0);
    616: }

    620: /*@C
    621:    SNESMonitorSetFromOptions - Sets a monitor function and viewer appropriate for the type indicated by the user

    623:    Collective on SNES

    625:    Input Parameters:
    626: +  snes - SNES object you wish to monitor
    627: .  name - the monitor type one is seeking
    628: .  help - message indicating what monitoring is done
    629: .  manual - manual page for the monitor
    630: .  monitor - the monitor function
    631: -  monitorsetup - a function that is called once ONLY if the user selected this monitor that may set additional features of the SNES or PetscViewer objects

    633:    Level: developer

    635: .seealso: PetscOptionsGetViewer(), PetscOptionsGetReal(), PetscOptionsHasName(), PetscOptionsGetString(),
    636:           PetscOptionsGetIntArray(), PetscOptionsGetRealArray(), PetscOptionsBool()
    637:           PetscOptionsInt(), PetscOptionsString(), PetscOptionsReal(), PetscOptionsBool(),
    638:           PetscOptionsName(), PetscOptionsBegin(), PetscOptionsEnd(), PetscOptionsHead(),
    639:           PetscOptionsStringArray(),PetscOptionsRealArray(), PetscOptionsScalar(),
    640:           PetscOptionsBoolGroupBegin(), PetscOptionsBoolGroup(), PetscOptionsBoolGroupEnd(),
    641:           PetscOptionsFList(), PetscOptionsEList()
    642: @*/
    643: PetscErrorCode  SNESMonitorSetFromOptions(SNES snes,const char name[],const char help[], const char manual[],PetscErrorCode (*monitor)(SNES,PetscInt,PetscReal,PetscViewerAndFormat*),PetscErrorCode (*monitorsetup)(SNES,PetscViewerAndFormat*))
    644: {
    645:   PetscErrorCode    ierr;
    646:   PetscViewer       viewer;
    647:   PetscViewerFormat format;
    648:   PetscBool         flg;

    651:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,name,&viewer,&format,&flg);
    652:   if (flg) {
    653:     PetscViewerAndFormat *vf;
    654:     PetscViewerAndFormatCreate(viewer,format,&vf);
    655:     PetscObjectDereference((PetscObject)viewer);
    656:     if (monitorsetup) {
    657:       (*monitorsetup)(snes,vf);
    658:     }
    659:     SNESMonitorSet(snes,(PetscErrorCode (*)(SNES,PetscInt,PetscReal,void*))monitor,vf,(PetscErrorCode (*)(void**))PetscViewerAndFormatDestroy);
    660:   }
    661:   return(0);
    662: }

    666: /*@
    667:    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.

    669:    Collective on SNES

    671:    Input Parameter:
    672: .  snes - the SNES context

    674:    Options Database Keys:
    675: +  -snes_type <type> - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, SNESType for complete list
    676: .  -snes_stol - convergence tolerance in terms of the norm
    677:                 of the change in the solution between steps
    678: .  -snes_atol <abstol> - absolute tolerance of residual norm
    679: .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
    680: .  -snes_max_it <max_it> - maximum number of iterations
    681: .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
    682: .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
    683: .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
    684: .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
    685: .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
    686: .  -snes_trtol <trtol> - trust region tolerance
    687: .  -snes_no_convergence_test - skip convergence test in nonlinear
    688:                                solver; hence iterations will continue until max_it
    689:                                or some other criterion is reached. Saves expense
    690:                                of convergence test
    691: .  -snes_monitor [ascii][:filename][:viewer format] - prints residual norm at each iteration. if no filename given prints to stdout
    692: .  -snes_monitor_solution [ascii binary draw][:filename][:viewer format] - plots solution at each iteration
    693: .  -snes_monitor_residual [ascii binary draw][:filename][:viewer format] - plots residual (not its norm) at each iteration
    694: .  -snes_monitor_solution_update [ascii binary draw][:filename][:viewer format] - plots update to solution at each iteration
    695: .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
    696: .  -snes_monitor_lg_range - plots residual norm at each iteration
    697: .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
    698: .  -snes_fd_color - use finite differences with coloring to compute Jacobian
    699: .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
    700: -  -snes_converged_reason - print the reason for convergence/divergence after each solve

    702:     Options Database for Eisenstat-Walker method:
    703: +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
    704: .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
    705: .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
    706: .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
    707: .  -snes_ksp_ew_gamma <gamma> - Sets gamma
    708: .  -snes_ksp_ew_alpha <alpha> - Sets alpha
    709: .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
    710: -  -snes_ksp_ew_threshold <threshold> - Sets threshold

    712:    Notes:
    713:    To see all options, run your program with the -help option or consult
    714:    Users-Manual: ch_snes

    716:    Level: beginner

    718: .keywords: SNES, nonlinear, set, options, database

    720: .seealso: SNESSetOptionsPrefix()
    721: @*/
    722: PetscErrorCode  SNESSetFromOptions(SNES snes)
    723: {
    724:   PetscBool      flg,pcset,persist,set;
    725:   PetscInt       i,indx,lag,grids;
    726:   const char     *deft        = SNESNEWTONLS;
    727:   const char     *convtests[] = {"default","skip"};
    728:   SNESKSPEW      *kctx        = NULL;
    729:   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
    731:   PCSide         pcside;
    732:   const char     *optionsprefix;

    736:   SNESRegisterAll();
    737:   PetscObjectOptionsBegin((PetscObject)snes);
    738:   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
    739:   PetscOptionsFList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);
    740:   if (flg) {
    741:     SNESSetType(snes,type);
    742:   } else if (!((PetscObject)snes)->type_name) {
    743:     SNESSetType(snes,deft);
    744:   }
    745:   PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,NULL);
    746:   PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,NULL);

    748:   PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,NULL);
    749:   PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,NULL);
    750:   PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,NULL);
    751:   PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,NULL);
    752:   PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,NULL);
    753:   PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,NULL);

    755:   PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);
    756:   if (flg) {
    757:     SNESSetLagPreconditioner(snes,lag);
    758:   }
    759:   PetscOptionsBool("-snes_lag_preconditioner_persists","Preconditioner lagging through multiple solves","SNESSetLagPreconditionerPersists",snes->lagjac_persist,&persist,&flg);
    760:   if (flg) {
    761:     SNESSetLagPreconditionerPersists(snes,persist);
    762:   }
    763:   PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);
    764:   if (flg) {
    765:     SNESSetLagJacobian(snes,lag);
    766:   }
    767:   PetscOptionsBool("-snes_lag_jacobian_persists","Jacobian lagging through multiple solves","SNESSetLagJacobianPersists",snes->lagjac_persist,&persist,&flg);
    768:   if (flg) {
    769:     SNESSetLagJacobianPersists(snes,persist);
    770:   }

    772:   PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);
    773:   if (flg) {
    774:     SNESSetGridSequence(snes,grids);
    775:   }

    777:   PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);
    778:   if (flg) {
    779:     switch (indx) {
    780:     case 0: SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL); break;
    781:     case 1: SNESSetConvergenceTest(snes,SNESConvergedSkip,NULL,NULL);    break;
    782:     }
    783:   }

    785:   PetscOptionsEList("-snes_norm_schedule","SNES Norm schedule","SNESSetNormSchedule",SNESNormSchedules,5,"function",&indx,&flg);
    786:   if (flg) { SNESSetNormSchedule(snes,(SNESNormSchedule)indx); }

    788:   PetscOptionsEList("-snes_function_type","SNES Norm schedule","SNESSetFunctionType",SNESFunctionTypes,2,"unpreconditioned",&indx,&flg);
    789:   if (flg) { SNESSetFunctionType(snes,(SNESFunctionType)indx); }

    791:   kctx = (SNESKSPEW*)snes->kspconvctx;

    793:   PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);

    795:   PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,NULL);
    796:   PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,NULL);
    797:   PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,NULL);
    798:   PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,NULL);
    799:   PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,NULL);
    800:   PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,NULL);
    801:   PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,NULL);

    803:   flg  = PETSC_FALSE;
    804:   PetscOptionsBool("-snes_check_jacobian","Check each Jacobian with a differenced one","SNESUpdateCheckJacobian",flg,&flg,&set);
    805:   if (set && flg) {
    806:     SNESSetUpdate(snes,SNESUpdateCheckJacobian);
    807:   }

    809:   flg  = PETSC_FALSE;
    810:   PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,&set);
    811:   if (set && flg) {SNESMonitorCancel(snes);}

    813:   SNESMonitorSetFromOptions(snes,"-snes_monitor","Monitor norm of function","SNESMonitorDefault",SNESMonitorDefault,NULL);
    814:   SNESMonitorSetFromOptions(snes,"-snes_monitor_short","Monitor norm of function with fewer digits","SNESMonitorDefaultShort",SNESMonitorDefaultShort,NULL);
    815:   SNESMonitorSetFromOptions(snes,"-snes_monitor_range","Monitor range of elements of function","SNESMonitorRange",SNESMonitorRange,NULL);

    817:   SNESMonitorSetFromOptions(snes,"-snes_monitor_ratio","Monitor ratios of the norm of function for consecutive steps","SNESMonitorRatio",SNESMonitorRatio,SNESMonitorRatioSetUp);
    818:   SNESMonitorSetFromOptions(snes,"-snes_monitor_field","Monitor norm of function (split into fields)","SNESMonitorDefaultField",SNESMonitorDefaultField,NULL);
    819:   SNESMonitorSetFromOptions(snes,"-snes_monitor_solution","View solution at each iteration","SNESMonitorSolution",SNESMonitorSolution,NULL);
    820:   SNESMonitorSetFromOptions(snes,"-snes_monitor_solution_update","View correction at each iteration","SNESMonitorSolutionUpdate",SNESMonitorSolutionUpdate,NULL);
    821:   SNESMonitorSetFromOptions(snes,"-snes_monitor_residual","View residual at each iteration","SNESMonitorResidual",SNESMonitorResidual,NULL);
    822:   SNESMonitorSetFromOptions(snes,"-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",SNESMonitorJacUpdateSpectrum,NULL);
    823:   SNESMonitorSetFromOptions(snes,"-snes_monitor_fields","Monitor norm of function per field","SNESMonitorSet",SNESMonitorFields,NULL);

    825:   PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);
    826:   if (flg) {PetscPythonMonitorSet((PetscObject)snes,monfilename);}

    829:   flg  = PETSC_FALSE;
    830:   PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);
    831:   if (flg) {
    832:     PetscDrawLG ctx;

    834:     SNESMonitorLGCreate(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,400,300,&ctx);
    835:     SNESMonitorSet(snes,SNESMonitorLGResidualNorm,ctx,(PetscErrorCode (*)(void**))PetscDrawLGDestroy);
    836:   }
    837:   flg  = PETSC_FALSE;
    838:   PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);
    839:   if (flg) {
    840:     PetscViewer ctx;

    842:     PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,400,300,&ctx);
    843:     SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);
    844:   }

    848:   flg  = PETSC_FALSE;
    849:   PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);
    850:   if (flg) {
    851:     void *functx;
    852:     SNESGetFunction(snes,NULL,NULL,&functx);
    853:     SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);
    854:     PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");
    855:   }

    857:   flg  = PETSC_FALSE;
    858:   PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);
    859:   if (flg) {
    860:     SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);
    861:   }

    863:   flg  = PETSC_FALSE;
    864:   PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);
    865:   if (flg) {
    866:     DM             dm;
    867:     DMSNES         sdm;
    868:     SNESGetDM(snes,&dm);
    869:     DMGetDMSNES(dm,&sdm);
    870:     sdm->jacobianctx = NULL;
    871:     SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,0);
    872:     PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");
    873:   }

    875:   flg  = PETSC_FALSE;
    876:   PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf_operator,&flg);
    877:   if (flg && snes->mf_operator) {
    878:     snes->mf_operator = PETSC_TRUE;
    879:     snes->mf          = PETSC_TRUE;
    880:   }
    881:   flg  = PETSC_FALSE;
    882:   PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf,&flg);
    883:   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
    884:   PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,0);

    886:   flg  = PETSC_FALSE;
    887:   SNESGetNPCSide(snes,&pcside);
    888:   PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetNPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);
    889:   if (flg) {SNESSetNPCSide(snes,pcside);}

    891: #if defined(PETSC_HAVE_SAWS)
    892:   /*
    893:     Publish convergence information using SAWs
    894:   */
    895:   flg  = PETSC_FALSE;
    896:   PetscOptionsBool("-snes_monitor_saws","Publish SNES progress using SAWs","SNESMonitorSet",flg,&flg,NULL);
    897:   if (flg) {
    898:     void *ctx;
    899:     SNESMonitorSAWsCreate(snes,&ctx);
    900:     SNESMonitorSet(snes,SNESMonitorSAWs,ctx,SNESMonitorSAWsDestroy);
    901:   }
    902: #endif
    903: #if defined(PETSC_HAVE_SAWS)
    904:   {
    905:   PetscBool set;
    906:   flg  = PETSC_FALSE;
    907:   PetscOptionsBool("-snes_saws_block","Block for SAWs at end of SNESSolve","PetscObjectSAWsBlock",((PetscObject)snes)->amspublishblock,&flg,&set);
    908:   if (set) {
    909:     PetscObjectSAWsSetBlock((PetscObject)snes,flg);
    910:   }
    911:   }
    912: #endif

    914:   for (i = 0; i < numberofsetfromoptions; i++) {
    915:     (*othersetfromoptions[i])(snes);
    916:   }

    918:   if (snes->ops->setfromoptions) {
    919:     (*snes->ops->setfromoptions)(PetscOptionsObject,snes);
    920:   }

    922:   /* process any options handlers added with PetscObjectAddOptionsHandler() */
    923:   PetscObjectProcessOptionsHandlers(PetscOptionsObject,(PetscObject)snes);
    924:   PetscOptionsEnd();

    926:   if (!snes->linesearch) {
    927:     SNESGetLineSearch(snes, &snes->linesearch);
    928:   }
    929:   SNESLineSearchSetFromOptions(snes->linesearch);

    931:   if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
    932:   KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);
    933:   KSPSetFromOptions(snes->ksp);

    935:   /* if someone has set the SNES NPC type, create it. */
    936:   SNESGetOptionsPrefix(snes, &optionsprefix);
    937:   PetscOptionsHasName(((PetscObject)snes)->options,optionsprefix, "-npc_snes_type", &pcset);
    938:   if (pcset && (!snes->pc)) {
    939:     SNESGetNPC(snes, &snes->pc);
    940:   }
    941:   return(0);
    942: }

    946: /*@C
    947:    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
    948:    the nonlinear solvers.

    950:    Logically Collective on SNES

    952:    Input Parameters:
    953: +  snes - the SNES context
    954: .  compute - function to compute the context
    955: -  destroy - function to destroy the context

    957:    Level: intermediate

    959:    Notes:
    960:    This function is currently not available from Fortran.

    962: .keywords: SNES, nonlinear, set, application, context

    964: .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
    965: @*/
    966: PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
    967: {
    970:   snes->ops->usercompute = compute;
    971:   snes->ops->userdestroy = destroy;
    972:   return(0);
    973: }

    977: /*@
    978:    SNESSetApplicationContext - Sets the optional user-defined context for
    979:    the nonlinear solvers.

    981:    Logically Collective on SNES

    983:    Input Parameters:
    984: +  snes - the SNES context
    985: -  usrP - optional user context

    987:    Level: intermediate

    989:    Fortran Notes: To use this from Fortran you must write a Fortran interface definition for this
    990:     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

    992: .keywords: SNES, nonlinear, set, application, context

    994: .seealso: SNESGetApplicationContext()
    995: @*/
    996: PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
    997: {
    999:   KSP            ksp;

    1003:   SNESGetKSP(snes,&ksp);
    1004:   KSPSetApplicationContext(ksp,usrP);
    1005:   snes->user = usrP;
    1006:   return(0);
    1007: }

    1011: /*@
    1012:    SNESGetApplicationContext - Gets the user-defined context for the
    1013:    nonlinear solvers.

    1015:    Not Collective

    1017:    Input Parameter:
    1018: .  snes - SNES context

    1020:    Output Parameter:
    1021: .  usrP - user context

    1023:    Fortran Notes: To use this from Fortran you must write a Fortran interface definition for this
    1024:     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

    1026:    Level: intermediate

    1028: .keywords: SNES, nonlinear, get, application, context

    1030: .seealso: SNESSetApplicationContext()
    1031: @*/
    1032: PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
    1033: {
    1036:   *(void**)usrP = snes->user;
    1037:   return(0);
    1038: }

    1042: /*@
    1043:    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
    1044:    at this time.

    1046:    Not Collective

    1048:    Input Parameter:
    1049: .  snes - SNES context

    1051:    Output Parameter:
    1052: .  iter - iteration number

    1054:    Notes:
    1055:    For example, during the computation of iteration 2 this would return 1.

    1057:    This is useful for using lagged Jacobians (where one does not recompute the
    1058:    Jacobian at each SNES iteration). For example, the code
    1059: .vb
    1060:       SNESGetIterationNumber(snes,&it);
    1061:       if (!(it % 2)) {
    1062:         [compute Jacobian here]
    1063:       }
    1064: .ve
    1065:    can be used in your ComputeJacobian() function to cause the Jacobian to be
    1066:    recomputed every second SNES iteration.

    1068:    Level: intermediate

    1070: .keywords: SNES, nonlinear, get, iteration, number,

    1072: .seealso:   SNESGetLinearSolveIterations()
    1073: @*/
    1074: PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
    1075: {
    1079:   *iter = snes->iter;
    1080:   return(0);
    1081: }

    1085: /*@
    1086:    SNESSetIterationNumber - Sets the current iteration number.

    1088:    Not Collective

    1090:    Input Parameter:
    1091: .  snes - SNES context
    1092: .  iter - iteration number

    1094:    Level: developer

    1096: .keywords: SNES, nonlinear, set, iteration, number,

    1098: .seealso:   SNESGetLinearSolveIterations()
    1099: @*/
    1100: PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
    1101: {

    1106:   PetscObjectSAWsTakeAccess((PetscObject)snes);
    1107:   snes->iter = iter;
    1108:   PetscObjectSAWsGrantAccess((PetscObject)snes);
    1109:   return(0);
    1110: }

    1114: /*@
    1115:    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
    1116:    attempted by the nonlinear solver.

    1118:    Not Collective

    1120:    Input Parameter:
    1121: .  snes - SNES context

    1123:    Output Parameter:
    1124: .  nfails - number of unsuccessful steps attempted

    1126:    Notes:
    1127:    This counter is reset to zero for each successive call to SNESSolve().

    1129:    Level: intermediate

    1131: .keywords: SNES, nonlinear, get, number, unsuccessful, steps

    1133: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
    1134:           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
    1135: @*/
    1136: PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
    1137: {
    1141:   *nfails = snes->numFailures;
    1142:   return(0);
    1143: }

    1147: /*@
    1148:    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
    1149:    attempted by the nonlinear solver before it gives up.

    1151:    Not Collective

    1153:    Input Parameters:
    1154: +  snes     - SNES context
    1155: -  maxFails - maximum of unsuccessful steps

    1157:    Level: intermediate

    1159: .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps

    1161: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
    1162:           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
    1163: @*/
    1164: PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
    1165: {
    1168:   snes->maxFailures = maxFails;
    1169:   return(0);
    1170: }

    1174: /*@
    1175:    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
    1176:    attempted by the nonlinear solver before it gives up.

    1178:    Not Collective

    1180:    Input Parameter:
    1181: .  snes     - SNES context

    1183:    Output Parameter:
    1184: .  maxFails - maximum of unsuccessful steps

    1186:    Level: intermediate

    1188: .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps

    1190: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
    1191:           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()

    1193: @*/
    1194: PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
    1195: {
    1199:   *maxFails = snes->maxFailures;
    1200:   return(0);
    1201: }

    1205: /*@
    1206:    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
    1207:      done by SNES.

    1209:    Not Collective

    1211:    Input Parameter:
    1212: .  snes     - SNES context

    1214:    Output Parameter:
    1215: .  nfuncs - number of evaluations

    1217:    Level: intermediate

    1219:    Notes: Reset every time SNESSolve is called unless SNESSetCountersReset() is used.

    1221: .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps

    1223: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
    1224: @*/
    1225: PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
    1226: {
    1230:   *nfuncs = snes->nfuncs;
    1231:   return(0);
    1232: }

    1236: /*@
    1237:    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
    1238:    linear solvers.

    1240:    Not Collective

    1242:    Input Parameter:
    1243: .  snes - SNES context

    1245:    Output Parameter:
    1246: .  nfails - number of failed solves

    1248:    Level: intermediate

    1250:    Options Database Keys:
    1251: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

    1253:    Notes:
    1254:    This counter is reset to zero for each successive call to SNESSolve().

    1256: .keywords: SNES, nonlinear, get, number, unsuccessful, steps

    1258: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
    1259: @*/
    1260: PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
    1261: {
    1265:   *nfails = snes->numLinearSolveFailures;
    1266:   return(0);
    1267: }

    1271: /*@
    1272:    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
    1273:    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE

    1275:    Logically Collective on SNES

    1277:    Input Parameters:
    1278: +  snes     - SNES context
    1279: -  maxFails - maximum allowed linear solve failures

    1281:    Level: intermediate

    1283:    Options Database Keys:
    1284: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

    1286:    Notes: By default this is 0; that is SNES returns on the first failed linear solve

    1288: .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps

    1290: .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
    1291: @*/
    1292: PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
    1293: {
    1297:   snes->maxLinearSolveFailures = maxFails;
    1298:   return(0);
    1299: }

    1303: /*@
    1304:    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
    1305:      are allowed before SNES terminates

    1307:    Not Collective

    1309:    Input Parameter:
    1310: .  snes     - SNES context

    1312:    Output Parameter:
    1313: .  maxFails - maximum of unsuccessful solves allowed

    1315:    Level: intermediate

    1317:    Notes: By default this is 1; that is SNES returns on the first failed linear solve

    1319: .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps

    1321: .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
    1322: @*/
    1323: PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
    1324: {
    1328:   *maxFails = snes->maxLinearSolveFailures;
    1329:   return(0);
    1330: }

    1334: /*@
    1335:    SNESGetLinearSolveIterations - Gets the total number of linear iterations
    1336:    used by the nonlinear solver.

    1338:    Not Collective

    1340:    Input Parameter:
    1341: .  snes - SNES context

    1343:    Output Parameter:
    1344: .  lits - number of linear iterations

    1346:    Notes:
    1347:    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.

    1349:    If the linear solver fails inside the SNESSolve() the iterations for that call to the linear solver are not included. If you wish to count them
    1350:    then call KSPGetIterationNumber() after the failed solve.

    1352:    Level: intermediate

    1354: .keywords: SNES, nonlinear, get, number, linear, iterations

    1356: .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
    1357: @*/
    1358: PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
    1359: {
    1363:   *lits = snes->linear_its;
    1364:   return(0);
    1365: }

    1369: /*@
    1370:    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
    1371:    are reset every time SNESSolve() is called.

    1373:    Logically Collective on SNES

    1375:    Input Parameter:
    1376: +  snes - SNES context
    1377: -  reset - whether to reset the counters or not

    1379:    Notes:
    1380:    This defaults to PETSC_TRUE

    1382:    Level: developer

    1384: .keywords: SNES, nonlinear, set, reset, number, linear, iterations

    1386: .seealso:  SNESGetNumberFunctionEvals(), SNESGetLinearSolveIterations(), SNESGetNPC()
    1387: @*/
    1388: PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
    1389: {
    1393:   snes->counters_reset = reset;
    1394:   return(0);
    1395: }

    1400: /*@
    1401:    SNESSetKSP - Sets a KSP context for the SNES object to use

    1403:    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm

    1405:    Input Parameters:
    1406: +  snes - the SNES context
    1407: -  ksp - the KSP context

    1409:    Notes:
    1410:    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
    1411:    so this routine is rarely needed.

    1413:    The KSP object that is already in the SNES object has its reference count
    1414:    decreased by one.

    1416:    Level: developer

    1418: .keywords: SNES, nonlinear, get, KSP, context

    1420: .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
    1421: @*/
    1422: PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
    1423: {

    1430:   PetscObjectReference((PetscObject)ksp);
    1431:   if (snes->ksp) {PetscObjectDereference((PetscObject)snes->ksp);}
    1432:   snes->ksp = ksp;
    1433:   return(0);
    1434: }

    1436: /* -----------------------------------------------------------*/
    1439: /*@
    1440:    SNESCreate - Creates a nonlinear solver context.

    1442:    Collective on MPI_Comm

    1444:    Input Parameters:
    1445: .  comm - MPI communicator

    1447:    Output Parameter:
    1448: .  outsnes - the new SNES context

    1450:    Options Database Keys:
    1451: +   -snes_mf - Activates default matrix-free Jacobian-vector products,
    1452:                and no preconditioning matrix
    1453: .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
    1454:                products, and a user-provided preconditioning matrix
    1455:                as set by SNESSetJacobian()
    1456: -   -snes_fd - Uses (slow!) finite differences to compute Jacobian

    1458:    Level: beginner

    1460: .keywords: SNES, nonlinear, create, context

    1462: .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()

    1464: @*/
    1465: PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
    1466: {
    1468:   SNES           snes;
    1469:   SNESKSPEW      *kctx;

    1473:   *outsnes = NULL;
    1474:   SNESInitializePackage();

    1476:   PetscHeaderCreate(snes,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);

    1478:   snes->ops->converged    = SNESConvergedDefault;
    1479:   snes->usesksp           = PETSC_TRUE;
    1480:   snes->tolerancesset     = PETSC_FALSE;
    1481:   snes->max_its           = 50;
    1482:   snes->max_funcs         = 10000;
    1483:   snes->norm              = 0.0;
    1484:   snes->normschedule      = SNES_NORM_ALWAYS;
    1485:   snes->functype          = SNES_FUNCTION_DEFAULT;
    1486: #if defined(PETSC_USE_REAL_SINGLE)
    1487:   snes->rtol              = 1.e-5;
    1488: #else
    1489:   snes->rtol              = 1.e-8;
    1490: #endif
    1491:   snes->ttol              = 0.0;
    1492: #if defined(PETSC_USE_REAL_SINGLE)
    1493:   snes->abstol            = 1.e-25;
    1494: #else
    1495:   snes->abstol            = 1.e-50;
    1496: #endif
    1497: #if defined(PETSC_USE_REAL_SINGLE)
    1498:   snes->stol              = 1.e-5;
    1499: #else
    1500:   snes->stol              = 1.e-8;
    1501: #endif
    1502: #if defined(PETSC_USE_REAL_SINGLE)
    1503:   snes->deltatol          = 1.e-6;
    1504: #else
    1505:   snes->deltatol          = 1.e-12;
    1506: #endif
    1507:   snes->nfuncs            = 0;
    1508:   snes->numFailures       = 0;
    1509:   snes->maxFailures       = 1;
    1510:   snes->linear_its        = 0;
    1511:   snes->lagjacobian       = 1;
    1512:   snes->jac_iter          = 0;
    1513:   snes->lagjac_persist    = PETSC_FALSE;
    1514:   snes->lagpreconditioner = 1;
    1515:   snes->pre_iter          = 0;
    1516:   snes->lagpre_persist    = PETSC_FALSE;
    1517:   snes->numbermonitors    = 0;
    1518:   snes->data              = 0;
    1519:   snes->setupcalled       = PETSC_FALSE;
    1520:   snes->ksp_ewconv        = PETSC_FALSE;
    1521:   snes->nwork             = 0;
    1522:   snes->work              = 0;
    1523:   snes->nvwork            = 0;
    1524:   snes->vwork             = 0;
    1525:   snes->conv_hist_len     = 0;
    1526:   snes->conv_hist_max     = 0;
    1527:   snes->conv_hist         = NULL;
    1528:   snes->conv_hist_its     = NULL;
    1529:   snes->conv_hist_reset   = PETSC_TRUE;
    1530:   snes->counters_reset    = PETSC_TRUE;
    1531:   snes->vec_func_init_set = PETSC_FALSE;
    1532:   snes->reason            = SNES_CONVERGED_ITERATING;
    1533:   snes->pcside            = PC_RIGHT;

    1535:   snes->mf          = PETSC_FALSE;
    1536:   snes->mf_operator = PETSC_FALSE;
    1537:   snes->mf_version  = 1;

    1539:   snes->numLinearSolveFailures = 0;
    1540:   snes->maxLinearSolveFailures = 1;

    1542:   snes->vizerotolerance = 1.e-8;

    1544:   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
    1545:   PetscNewLog(snes,&kctx);

    1547:   snes->kspconvctx  = (void*)kctx;
    1548:   kctx->version     = 2;
    1549:   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
    1550:                              this was too large for some test cases */
    1551:   kctx->rtol_last   = 0.0;
    1552:   kctx->rtol_max    = .9;
    1553:   kctx->gamma       = 1.0;
    1554:   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
    1555:   kctx->alpha2      = kctx->alpha;
    1556:   kctx->threshold   = .1;
    1557:   kctx->lresid_last = 0.0;
    1558:   kctx->norm_last   = 0.0;

    1560:   *outsnes = snes;
    1561:   return(0);
    1562: }

    1564: /*MC
    1565:     SNESFunction - Functional form used to convey the nonlinear function to be solved by SNES

    1567:      Synopsis:
    1568:      #include "petscsnes.h"
    1569:      PetscErrorCode SNESFunction(SNES snes,Vec x,Vec f,void *ctx);

    1571:      Input Parameters:
    1572: +     snes - the SNES context
    1573: .     x    - state at which to evaluate residual
    1574: -     ctx     - optional user-defined function context, passed in with SNESSetFunction()

    1576:      Output Parameter:
    1577: .     f  - vector to put residual (function value)

    1579:    Level: intermediate

    1581: .seealso:   SNESSetFunction(), SNESGetFunction()
    1582: M*/

    1586: /*@C
    1587:    SNESSetFunction - Sets the function evaluation routine and function
    1588:    vector for use by the SNES routines in solving systems of nonlinear
    1589:    equations.

    1591:    Logically Collective on SNES

    1593:    Input Parameters:
    1594: +  snes - the SNES context
    1595: .  r - vector to store function value
    1596: .  f - function evaluation routine; see SNESFunction for calling sequence details
    1597: -  ctx - [optional] user-defined context for private data for the
    1598:          function evaluation routine (may be NULL)

    1600:    Notes:
    1601:    The Newton-like methods typically solve linear systems of the form
    1602: $      f'(x) x = -f(x),
    1603:    where f'(x) denotes the Jacobian matrix and f(x) is the function.

    1605:    Level: beginner

    1607: .keywords: SNES, nonlinear, set, function

    1609: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
    1610: @*/
    1611: PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
    1612: {
    1614:   DM             dm;

    1618:   if (r) {
    1621:     PetscObjectReference((PetscObject)r);
    1622:     VecDestroy(&snes->vec_func);

    1624:     snes->vec_func = r;
    1625:   }
    1626:   SNESGetDM(snes,&dm);
    1627:   DMSNESSetFunction(dm,f,ctx);
    1628:   return(0);
    1629: }

    1634: /*@C
    1635:    SNESSetInitialFunction - Sets the function vector to be used as the
    1636:    function norm at the initialization of the method.  In some
    1637:    instances, the user has precomputed the function before calling
    1638:    SNESSolve.  This function allows one to avoid a redundant call
    1639:    to SNESComputeFunction in that case.

    1641:    Logically Collective on SNES

    1643:    Input Parameters:
    1644: +  snes - the SNES context
    1645: -  f - vector to store function value

    1647:    Notes:
    1648:    This should not be modified during the solution procedure.

    1650:    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.

    1652:    Level: developer

    1654: .keywords: SNES, nonlinear, set, function

    1656: .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
    1657: @*/
    1658: PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
    1659: {
    1661:   Vec            vec_func;

    1667:   if (snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
    1668:     snes->vec_func_init_set = PETSC_FALSE;
    1669:     return(0);
    1670:   }
    1671:   SNESGetFunction(snes,&vec_func,NULL,NULL);
    1672:   VecCopy(f, vec_func);

    1674:   snes->vec_func_init_set = PETSC_TRUE;
    1675:   return(0);
    1676: }

    1680: /*@
    1681:    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
    1682:    of the SNES method.

    1684:    Logically Collective on SNES

    1686:    Input Parameters:
    1687: +  snes - the SNES context
    1688: -  normschedule - the frequency of norm computation

    1690:    Options Database Key:
    1691: .  -snes_norm_schedule <none, always, initialonly, finalonly, initalfinalonly>

    1693:    Notes:
    1694:    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
    1695:    of the nonlinear function and the taking of its norm at every iteration to
    1696:    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
    1697:    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
    1698:    may either be monitored for convergence or not.  As these are often used as nonlinear
    1699:    preconditioners, monitoring the norm of their error is not a useful enterprise within
    1700:    their solution.

    1702:    Level: developer

    1704: .keywords: SNES, nonlinear, set, function, norm, type

    1706: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
    1707: @*/
    1708: PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
    1709: {
    1712:   snes->normschedule = normschedule;
    1713:   return(0);
    1714: }

    1719: /*@
    1720:    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
    1721:    of the SNES method.

    1723:    Logically Collective on SNES

    1725:    Input Parameters:
    1726: +  snes - the SNES context
    1727: -  normschedule - the type of the norm used

    1729:    Level: advanced

    1731: .keywords: SNES, nonlinear, set, function, norm, type

    1733: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
    1734: @*/
    1735: PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
    1736: {
    1739:   *normschedule = snes->normschedule;
    1740:   return(0);
    1741: }

    1746: /*@
    1747:   SNESSetFunctionNorm - Sets the last computed residual norm.

    1749:   Logically Collective on SNES

    1751:   Input Parameters:
    1752: + snes - the SNES context

    1754: - normschedule - the frequency of norm computation

    1756:   Level: developer

    1758: .keywords: SNES, nonlinear, set, function, norm, type
    1759: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
    1760: @*/
    1761: PetscErrorCode SNESSetFunctionNorm(SNES snes, PetscReal norm)
    1762: {
    1765:   snes->norm = norm;
    1766:   return(0);
    1767: }

    1771: /*@
    1772:   SNESGetFunctionNorm - Gets the last computed norm of the residual

    1774:   Not Collective

    1776:   Input Parameter:
    1777: . snes - the SNES context

    1779:   Output Parameter:
    1780: . norm - the last computed residual norm

    1782:   Level: developer

    1784: .keywords: SNES, nonlinear, set, function, norm, type
    1785: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
    1786: @*/
    1787: PetscErrorCode SNESGetFunctionNorm(SNES snes, PetscReal *norm)
    1788: {
    1792:   *norm = snes->norm;
    1793:   return(0);
    1794: }

    1798: /*@C
    1799:    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
    1800:    of the SNES method.

    1802:    Logically Collective on SNES

    1804:    Input Parameters:
    1805: +  snes - the SNES context
    1806: -  normschedule - the frequency of norm computation

    1808:    Notes:
    1809:    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
    1810:    of the nonlinear function and the taking of its norm at every iteration to
    1811:    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
    1812:    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
    1813:    may either be monitored for convergence or not.  As these are often used as nonlinear
    1814:    preconditioners, monitoring the norm of their error is not a useful enterprise within
    1815:    their solution.

    1817:    Level: developer

    1819: .keywords: SNES, nonlinear, set, function, norm, type

    1821: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
    1822: @*/
    1823: PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
    1824: {
    1827:   snes->functype = type;
    1828:   return(0);
    1829: }

    1834: /*@C
    1835:    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
    1836:    of the SNES method.

    1838:    Logically Collective on SNES

    1840:    Input Parameters:
    1841: +  snes - the SNES context
    1842: -  normschedule - the type of the norm used

    1844:    Level: advanced

    1846: .keywords: SNES, nonlinear, set, function, norm, type

    1848: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
    1849: @*/
    1850: PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
    1851: {
    1854:   *type = snes->functype;
    1855:   return(0);
    1856: }

    1858: /*MC
    1859:     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function

    1861:      Synopsis:
    1862:      #include <petscsnes.h>
    1863: $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);

    1865: +  X   - solution vector
    1866: .  B   - RHS vector
    1867: -  ctx - optional user-defined Gauss-Seidel context

    1869:    Level: intermediate

    1871: .seealso:   SNESSetNGS(), SNESGetNGS()
    1872: M*/

    1876: /*@C
    1877:    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
    1878:    use with composed nonlinear solvers.

    1880:    Input Parameters:
    1881: +  snes   - the SNES context
    1882: .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
    1883: -  ctx    - [optional] user-defined context for private data for the
    1884:             smoother evaluation routine (may be NULL)

    1886:    Notes:
    1887:    The NGS routines are used by the composed nonlinear solver to generate
    1888:     a problem appropriate update to the solution, particularly FAS.

    1890:    Level: intermediate

    1892: .keywords: SNES, nonlinear, set, Gauss-Seidel

    1894: .seealso: SNESGetFunction(), SNESComputeNGS()
    1895: @*/
    1896: PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
    1897: {
    1899:   DM             dm;

    1903:   SNESGetDM(snes,&dm);
    1904:   DMSNESSetNGS(dm,f,ctx);
    1905:   return(0);
    1906: }

    1910: PETSC_EXTERN PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
    1911: {
    1913:   DM             dm;
    1914:   DMSNES         sdm;

    1917:   SNESGetDM(snes,&dm);
    1918:   DMGetDMSNES(dm,&sdm);
    1919:   /*  A(x)*x - b(x) */
    1920:   if (sdm->ops->computepfunction) {
    1921:     (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);
    1922:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");

    1924:   if (sdm->ops->computepjacobian) {
    1925:     (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);
    1926:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
    1927:   VecScale(f,-1.0);
    1928:   MatMultAdd(snes->jacobian,x,f,f);
    1929:   return(0);
    1930: }

    1934: PETSC_EXTERN PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
    1935: {
    1937:   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
    1938:   return(0);
    1939: }

    1943: /*@C
    1944:    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)

    1946:    Logically Collective on SNES

    1948:    Input Parameters:
    1949: +  snes - the SNES context
    1950: .  r - vector to store function value
    1951: .  b - function evaluation routine
    1952: .  Amat - matrix with which A(x) x - b(x) is to be computed
    1953: .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
    1954: .  J  - function to compute matrix value, see SNESJacobianFunction for details on its calling sequence
    1955: -  ctx - [optional] user-defined context for private data for the
    1956:          function evaluation routine (may be NULL)

    1958:    Notes:
    1959:     We do not recomemend using this routine. It is far better to provide the nonlinear function F() and some approximation to the Jacobian and use
    1960:     an approximate Newton solver. This interface is provided to allow porting/testing a previous Picard based code in PETSc before converting it to approximate Newton.

    1962:     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both

    1964: $     Solves the equation A(x) x = b(x) via the defect correction algorithm A(x^{n}) (x^{n+1} - x^{n}) = b(x^{n}) - A(x^{n})x^{n}
    1965: $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.

    1967:      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.

    1969:    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
    1970:    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)

    1972:    There is some controversity over the definition of a Picard iteration for nonlinear systems but almost everyone agrees that it involves a linear solve and some
    1973:    believe it is the iteration  A(x^{n}) x^{n+1} = b(x^{n}) hence we use the name Picard. If anyone has an authoritative  reference that defines the Picard iteration
    1974:    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).

    1976:    Level: intermediate

    1978: .keywords: SNES, nonlinear, set, function

    1980: .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard(), SNESJacobianFunction
    1981: @*/
    1982: PetscErrorCode  SNESSetPicard(SNES snes,Vec r,PetscErrorCode (*b)(SNES,Vec,Vec,void*),Mat Amat, Mat Pmat, PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
    1983: {
    1985:   DM             dm;

    1989:   SNESGetDM(snes, &dm);
    1990:   DMSNESSetPicard(dm,b,J,ctx);
    1991:   SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);
    1992:   SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);
    1993:   return(0);
    1994: }

    1998: /*@C
    1999:    SNESGetPicard - Returns the context for the Picard iteration

    2001:    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.

    2003:    Input Parameter:
    2004: .  snes - the SNES context

    2006:    Output Parameter:
    2007: +  r - the function (or NULL)
    2008: .  f - the function (or NULL); see SNESFunction for calling sequence details
    2009: .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
    2010: .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
    2011: .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
    2012: -  ctx - the function context (or NULL)

    2014:    Level: advanced

    2016: .keywords: SNES, nonlinear, get, function

    2018: .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
    2019: @*/
    2020: PetscErrorCode  SNESGetPicard(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),Mat *Amat, Mat *Pmat, PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
    2021: {
    2023:   DM             dm;

    2027:   SNESGetFunction(snes,r,NULL,NULL);
    2028:   SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);
    2029:   SNESGetDM(snes,&dm);
    2030:   DMSNESGetPicard(dm,f,J,ctx);
    2031:   return(0);
    2032: }

    2036: /*@C
    2037:    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem

    2039:    Logically Collective on SNES

    2041:    Input Parameters:
    2042: +  snes - the SNES context
    2043: .  func - function evaluation routine
    2044: -  ctx - [optional] user-defined context for private data for the
    2045:          function evaluation routine (may be NULL)

    2047:    Calling sequence of func:
    2048: $    func (SNES snes,Vec x,void *ctx);

    2050: .  f - function vector
    2051: -  ctx - optional user-defined function context

    2053:    Level: intermediate

    2055: .keywords: SNES, nonlinear, set, function

    2057: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
    2058: @*/
    2059: PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
    2060: {
    2063:   if (func) snes->ops->computeinitialguess = func;
    2064:   if (ctx)  snes->initialguessP            = ctx;
    2065:   return(0);
    2066: }

    2068: /* --------------------------------------------------------------- */
    2071: /*@C
    2072:    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
    2073:    it assumes a zero right hand side.

    2075:    Logically Collective on SNES

    2077:    Input Parameter:
    2078: .  snes - the SNES context

    2080:    Output Parameter:
    2081: .  rhs - the right hand side vector or NULL if the right hand side vector is null

    2083:    Level: intermediate

    2085: .keywords: SNES, nonlinear, get, function, right hand side

    2087: .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
    2088: @*/
    2089: PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
    2090: {
    2094:   *rhs = snes->vec_rhs;
    2095:   return(0);
    2096: }

    2100: /*@
    2101:    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().

    2103:    Collective on SNES

    2105:    Input Parameters:
    2106: +  snes - the SNES context
    2107: -  x - input vector

    2109:    Output Parameter:
    2110: .  y - function vector, as set by SNESSetFunction()

    2112:    Notes:
    2113:    SNESComputeFunction() is typically used within nonlinear solvers
    2114:    implementations, so most users would not generally call this routine
    2115:    themselves.

    2117:    Level: developer

    2119: .keywords: SNES, nonlinear, compute, function

    2121: .seealso: SNESSetFunction(), SNESGetFunction()
    2122: @*/
    2123: PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
    2124: {
    2126:   DM             dm;
    2127:   DMSNES         sdm;

    2135:   VecValidValues(x,2,PETSC_TRUE);

    2137:   SNESGetDM(snes,&dm);
    2138:   DMGetDMSNES(dm,&sdm);
    2139:   if (sdm->ops->computefunction) {
    2140:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
    2141:       PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);
    2142:     }
    2143:     VecLockPush(x);
    2144:     PetscStackPush("SNES user function");
    2145:     (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);
    2146:     PetscStackPop;
    2147:     VecLockPop(x);
    2148:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
    2149:       PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);
    2150:     }
    2151:   } else if (snes->vec_rhs) {
    2152:     MatMult(snes->jacobian, x, y);
    2153:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
    2154:   if (snes->vec_rhs) {
    2155:     VecAXPY(y,-1.0,snes->vec_rhs);
    2156:   }
    2157:   snes->nfuncs++;
    2158:   /*
    2159:      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
    2160:      propagate the value to all processes
    2161:   */
    2162:   if (snes->domainerror) {
    2163:     VecSetInf(y);
    2164:   }
    2165:   return(0);
    2166: }

    2170: /*@
    2171:    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().

    2173:    Collective on SNES

    2175:    Input Parameters:
    2176: +  snes - the SNES context
    2177: .  x - input vector
    2178: -  b - rhs vector

    2180:    Output Parameter:
    2181: .  x - new solution vector

    2183:    Notes:
    2184:    SNESComputeNGS() is typically used within composed nonlinear solver
    2185:    implementations, so most users would not generally call this routine
    2186:    themselves.

    2188:    Level: developer

    2190: .keywords: SNES, nonlinear, compute, function

    2192: .seealso: SNESSetNGS(), SNESComputeFunction()
    2193: @*/
    2194: PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
    2195: {
    2197:   DM             dm;
    2198:   DMSNES         sdm;

    2206:   if (b) {VecValidValues(b,2,PETSC_TRUE);}
    2207:   PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);
    2208:   SNESGetDM(snes,&dm);
    2209:   DMGetDMSNES(dm,&sdm);
    2210:   if (sdm->ops->computegs) {
    2211:     if (b) {VecLockPush(b);}
    2212:     PetscStackPush("SNES user NGS");
    2213:     (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);
    2214:     PetscStackPop;
    2215:     if (b) {VecLockPop(b);}
    2216:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
    2217:   PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);
    2218:   return(0);
    2219: }

    2223: /*@
    2224:    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().

    2226:    Collective on SNES and Mat

    2228:    Input Parameters:
    2229: +  snes - the SNES context
    2230: -  x - input vector

    2232:    Output Parameters:
    2233: +  A - Jacobian matrix
    2234: -  B - optional preconditioning matrix

    2236:   Options Database Keys:
    2237: +    -snes_lag_preconditioner <lag>
    2238: .    -snes_lag_jacobian <lag>
    2239: .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
    2240: .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
    2241: .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
    2242: .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
    2243: .    -snes_compare_coloring - Compute the finite difference Jacobian using coloring and display norms of difference
    2244: .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
    2245: .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
    2246: .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
    2247: .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
    2248: .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
    2249: -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences

    2252:    Notes:
    2253:    Most users should not need to explicitly call this routine, as it
    2254:    is used internally within the nonlinear solvers.

    2256:    Level: developer

    2258: .keywords: SNES, compute, Jacobian, matrix

    2260: .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
    2261: @*/
    2262: PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
    2263: {
    2265:   PetscBool      flag;
    2266:   DM             dm;
    2267:   DMSNES         sdm;
    2268:   KSP            ksp;

    2274:   VecValidValues(X,2,PETSC_TRUE);
    2275:   SNESGetDM(snes,&dm);
    2276:   DMGetDMSNES(dm,&sdm);

    2278:   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");

    2280:   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */

    2282:   if (snes->lagjacobian == -2) {
    2283:     snes->lagjacobian = -1;

    2285:     PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");
    2286:   } else if (snes->lagjacobian == -1) {
    2287:     PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");
    2288:     PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);
    2289:     if (flag) {
    2290:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
    2291:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
    2292:     }
    2293:     return(0);
    2294:   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
    2295:     PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);
    2296:     PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);
    2297:     if (flag) {
    2298:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
    2299:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
    2300:     }
    2301:     return(0);
    2302:   }
    2303:   if (snes->pc && snes->pcside == PC_LEFT) {
    2304:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
    2305:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
    2306:       return(0);
    2307:   }

    2309:   PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);
    2310:   VecLockPush(X);
    2311:   PetscStackPush("SNES user Jacobian function");
    2312:   (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);
    2313:   PetscStackPop;
    2314:   VecLockPop(X);
    2315:   PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);

    2317:   /* the next line ensures that snes->ksp exists */
    2318:   SNESGetKSP(snes,&ksp);
    2319:   if (snes->lagpreconditioner == -2) {
    2320:     PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");
    2321:     KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);
    2322:     snes->lagpreconditioner = -1;
    2323:   } else if (snes->lagpreconditioner == -1) {
    2324:     PetscInfo(snes,"Reusing preconditioner because lag is -1\n");
    2325:     KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);
    2326:   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
    2327:     PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);
    2328:     KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);
    2329:   } else {
    2330:     PetscInfo(snes,"Rebuilding preconditioner\n");
    2331:     KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);
    2332:   }

    2334:   /* make sure user returned a correct Jacobian and preconditioner */
    2337:   {
    2338:     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
    2339:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_explicit",NULL,NULL,&flag);
    2340:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",NULL,NULL,&flag_draw);
    2341:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",NULL,NULL,&flag_contour);
    2342:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_operator",NULL,NULL,&flag_operator);
    2343:     if (flag || flag_draw || flag_contour) {
    2344:       Mat          Bexp_mine = NULL,Bexp,FDexp;
    2345:       PetscViewer  vdraw,vstdout;
    2346:       PetscBool    flg;
    2347:       if (flag_operator) {
    2348:         MatComputeExplicitOperator(A,&Bexp_mine);
    2349:         Bexp = Bexp_mine;
    2350:       } else {
    2351:         /* See if the preconditioning matrix can be viewed and added directly */
    2352:         PetscObjectTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");
    2353:         if (flg) Bexp = B;
    2354:         else {
    2355:           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
    2356:           MatComputeExplicitOperator(B,&Bexp_mine);
    2357:           Bexp = Bexp_mine;
    2358:         }
    2359:       }
    2360:       MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);
    2361:       SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);
    2362:       PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);
    2363:       if (flag_draw || flag_contour) {
    2364:         PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);
    2365:         if (flag_contour) {PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);}
    2366:       } else vdraw = NULL;
    2367:       PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");
    2368:       if (flag) {MatView(Bexp,vstdout);}
    2369:       if (vdraw) {MatView(Bexp,vdraw);}
    2370:       PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");
    2371:       if (flag) {MatView(FDexp,vstdout);}
    2372:       if (vdraw) {MatView(FDexp,vdraw);}
    2373:       MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);
    2374:       PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");
    2375:       if (flag) {MatView(FDexp,vstdout);}
    2376:       if (vdraw) {              /* Always use contour for the difference */
    2377:         PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
    2378:         MatView(FDexp,vdraw);
    2379:         PetscViewerPopFormat(vdraw);
    2380:       }
    2381:       if (flag_contour) {PetscViewerPopFormat(vdraw);}
    2382:       PetscViewerDestroy(&vdraw);
    2383:       MatDestroy(&Bexp_mine);
    2384:       MatDestroy(&FDexp);
    2385:     }
    2386:   }
    2387:   {
    2388:     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
    2389:     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
    2390:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_coloring",NULL,NULL,&flag);
    2391:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_coloring_display",NULL,NULL,&flag_display);
    2392:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",NULL,NULL,&flag_draw);
    2393:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",NULL,NULL,&flag_contour);
    2394:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",NULL,NULL,&flag_threshold);
    2395:     if (flag_threshold) {
    2396:       PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);
    2397:       PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);
    2398:     }
    2399:     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
    2400:       Mat            Bfd;
    2401:       PetscViewer    vdraw,vstdout;
    2402:       MatColoring    coloring;
    2403:       ISColoring     iscoloring;
    2404:       MatFDColoring  matfdcoloring;
    2405:       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
    2406:       void           *funcctx;
    2407:       PetscReal      norm1,norm2,normmax;

    2409:       MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);
    2410:       MatColoringCreate(Bfd,&coloring);
    2411:       MatColoringSetType(coloring,MATCOLORINGSL);
    2412:       MatColoringSetFromOptions(coloring);
    2413:       MatColoringApply(coloring,&iscoloring);
    2414:       MatColoringDestroy(&coloring);
    2415:       MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);
    2416:       MatFDColoringSetFromOptions(matfdcoloring);
    2417:       MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);
    2418:       ISColoringDestroy(&iscoloring);

    2420:       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
    2421:       SNESGetFunction(snes,NULL,&func,&funcctx);
    2422:       MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);
    2423:       PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);
    2424:       PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");
    2425:       MatFDColoringSetFromOptions(matfdcoloring);
    2426:       MatFDColoringApply(Bfd,matfdcoloring,X,snes);
    2427:       MatFDColoringDestroy(&matfdcoloring);

    2429:       PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);
    2430:       if (flag_draw || flag_contour) {
    2431:         PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);
    2432:         if (flag_contour) {PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);}
    2433:       } else vdraw = NULL;
    2434:       PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");
    2435:       if (flag_display) {MatView(B,vstdout);}
    2436:       if (vdraw) {MatView(B,vdraw);}
    2437:       PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");
    2438:       if (flag_display) {MatView(Bfd,vstdout);}
    2439:       if (vdraw) {MatView(Bfd,vdraw);}
    2440:       MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);
    2441:       MatNorm(Bfd,NORM_1,&norm1);
    2442:       MatNorm(Bfd,NORM_FROBENIUS,&norm2);
    2443:       MatNorm(Bfd,NORM_MAX,&normmax);
    2444:       PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%g normFrob=%g normmax=%g\n",(double)norm1,(double)norm2,(double)normmax);
    2445:       if (flag_display) {MatView(Bfd,vstdout);}
    2446:       if (vdraw) {              /* Always use contour for the difference */
    2447:         PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
    2448:         MatView(Bfd,vdraw);
    2449:         PetscViewerPopFormat(vdraw);
    2450:       }
    2451:       if (flag_contour) {PetscViewerPopFormat(vdraw);}

    2453:       if (flag_threshold) {
    2454:         PetscInt bs,rstart,rend,i;
    2455:         MatGetBlockSize(B,&bs);
    2456:         MatGetOwnershipRange(B,&rstart,&rend);
    2457:         for (i=rstart; i<rend; i++) {
    2458:           const PetscScalar *ba,*ca;
    2459:           const PetscInt    *bj,*cj;
    2460:           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
    2461:           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
    2462:           MatGetRow(B,i,&bn,&bj,&ba);
    2463:           MatGetRow(Bfd,i,&cn,&cj,&ca);
    2464:           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
    2465:           for (j=0; j<bn; j++) {
    2466:             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
    2467:             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
    2468:               maxentrycol = bj[j];
    2469:               maxentry    = PetscRealPart(ba[j]);
    2470:             }
    2471:             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
    2472:               maxdiffcol = bj[j];
    2473:               maxdiff    = PetscRealPart(ca[j]);
    2474:             }
    2475:             if (rdiff > maxrdiff) {
    2476:               maxrdiffcol = bj[j];
    2477:               maxrdiff    = rdiff;
    2478:             }
    2479:           }
    2480:           if (maxrdiff > 1) {
    2481:             PetscViewerASCIIPrintf(vstdout,"row %D (maxentry=%g at %D, maxdiff=%g at %D, maxrdiff=%g at %D):",i,(double)maxentry,maxentrycol,(double)maxdiff,maxdiffcol,(double)maxrdiff,maxrdiffcol);
    2482:             for (j=0; j<bn; j++) {
    2483:               PetscReal rdiff;
    2484:               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
    2485:               if (rdiff > 1) {
    2486:                 PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));
    2487:               }
    2488:             }
    2489:             PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);
    2490:           }
    2491:           MatRestoreRow(B,i,&bn,&bj,&ba);
    2492:           MatRestoreRow(Bfd,i,&cn,&cj,&ca);
    2493:         }
    2494:       }
    2495:       PetscViewerDestroy(&vdraw);
    2496:       MatDestroy(&Bfd);
    2497:     }
    2498:   }
    2499:   return(0);
    2500: }

    2502: /*MC
    2503:     SNESJacobianFunction - Function used to convey the nonlinear Jacobian of the function to be solved by SNES

    2505:      Synopsis:
    2506:      #include "petscsnes.h"
    2507:      PetscErrorCode SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);

    2509: +  x - input vector
    2510: .  Amat - the matrix that defines the (approximate) Jacobian
    2511: .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
    2512: -  ctx - [optional] user-defined Jacobian context

    2514:    Level: intermediate

    2516: .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
    2517: M*/

    2521: /*@C
    2522:    SNESSetJacobian - Sets the function to compute Jacobian as well as the
    2523:    location to store the matrix.

    2525:    Logically Collective on SNES and Mat

    2527:    Input Parameters:
    2528: +  snes - the SNES context
    2529: .  Amat - the matrix that defines the (approximate) Jacobian
    2530: .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
    2531: .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value), see SNESJacobianFunction for details
    2532: -  ctx - [optional] user-defined context for private data for the
    2533:          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)

    2535:    Notes:
    2536:    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
    2537:    each matrix.

    2539:    If you know the operator Amat has a null space you can use MatSetNullSpace() and MatSetTransposeNullSpace() to supply the null
    2540:    space to Amat and the KSP solvers will automatically use that null space as needed during the solution process.

    2542:    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
    2543:    must be a MatFDColoring.

    2545:    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
    2546:    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.

    2548:    Level: beginner

    2550: .keywords: SNES, nonlinear, set, Jacobian, matrix

    2552: .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J,
    2553:           SNESSetPicard(), SNESJacobianFunction
    2554: @*/
    2555: PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
    2556: {
    2558:   DM             dm;

    2566:   SNESGetDM(snes,&dm);
    2567:   DMSNESSetJacobian(dm,J,ctx);
    2568:   if (Amat) {
    2569:     PetscObjectReference((PetscObject)Amat);
    2570:     MatDestroy(&snes->jacobian);

    2572:     snes->jacobian = Amat;
    2573:   }
    2574:   if (Pmat) {
    2575:     PetscObjectReference((PetscObject)Pmat);
    2576:     MatDestroy(&snes->jacobian_pre);

    2578:     snes->jacobian_pre = Pmat;
    2579:   }
    2580:   return(0);
    2581: }

    2585: /*@C
    2586:    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
    2587:    provided context for evaluating the Jacobian.

    2589:    Not Collective, but Mat object will be parallel if SNES object is

    2591:    Input Parameter:
    2592: .  snes - the nonlinear solver context

    2594:    Output Parameters:
    2595: +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
    2596: .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
    2597: .  J - location to put Jacobian function (or NULL), see SNESJacobianFunction for details on its calling sequence
    2598: -  ctx - location to stash Jacobian ctx (or NULL)

    2600:    Level: advanced

    2602: .seealso: SNESSetJacobian(), SNESComputeJacobian(), SNESJacobianFunction, SNESGetFunction()
    2603: @*/
    2604: PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
    2605: {
    2607:   DM             dm;
    2608:   DMSNES         sdm;

    2612:   if (Amat) *Amat = snes->jacobian;
    2613:   if (Pmat) *Pmat = snes->jacobian_pre;
    2614:   SNESGetDM(snes,&dm);
    2615:   DMGetDMSNES(dm,&sdm);
    2616:   if (J) *J = sdm->ops->computejacobian;
    2617:   if (ctx) *ctx = sdm->jacobianctx;
    2618:   return(0);
    2619: }

    2623: /*@
    2624:    SNESSetUp - Sets up the internal data structures for the later use
    2625:    of a nonlinear solver.

    2627:    Collective on SNES

    2629:    Input Parameters:
    2630: .  snes - the SNES context

    2632:    Notes:
    2633:    For basic use of the SNES solvers the user need not explicitly call
    2634:    SNESSetUp(), since these actions will automatically occur during
    2635:    the call to SNESSolve().  However, if one wishes to control this
    2636:    phase separately, SNESSetUp() should be called after SNESCreate()
    2637:    and optional routines of the form SNESSetXXX(), but before SNESSolve().

    2639:    Level: advanced

    2641: .keywords: SNES, nonlinear, setup

    2643: .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
    2644: @*/
    2645: PetscErrorCode  SNESSetUp(SNES snes)
    2646: {
    2648:   DM             dm;
    2649:   DMSNES         sdm;
    2650:   SNESLineSearch linesearch, pclinesearch;
    2651:   void           *lsprectx,*lspostctx;
    2652:   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
    2653:   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
    2654:   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
    2655:   Vec            f,fpc;
    2656:   void           *funcctx;
    2657:   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
    2658:   void           *jacctx,*appctx;
    2659:   Mat            j,jpre;

    2663:   if (snes->setupcalled) return(0);

    2665:   if (!((PetscObject)snes)->type_name) {
    2666:     SNESSetType(snes,SNESNEWTONLS);
    2667:   }

    2669:   SNESGetFunction(snes,&snes->vec_func,NULL,NULL);

    2671:   SNESGetDM(snes,&dm);
    2672:   DMGetDMSNES(dm,&sdm);
    2673:   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
    2674:   if (!sdm->ops->computejacobian) {
    2675:     DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);
    2676:   }
    2677:   if (!snes->vec_func) {
    2678:     DMCreateGlobalVector(dm,&snes->vec_func);
    2679:   }

    2681:   if (!snes->ksp) {
    2682:     SNESGetKSP(snes, &snes->ksp);
    2683:   }

    2685:   if (!snes->linesearch) {
    2686:     SNESGetLineSearch(snes, &snes->linesearch);
    2687:   }
    2688:   SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);

    2690:   if (snes->pc && (snes->pcside == PC_LEFT)) {
    2691:     snes->mf          = PETSC_TRUE;
    2692:     snes->mf_operator = PETSC_FALSE;
    2693:   }

    2695:   if (snes->pc) {
    2696:     /* copy the DM over */
    2697:     SNESGetDM(snes,&dm);
    2698:     SNESSetDM(snes->pc,dm);

    2700:     SNESGetFunction(snes,&f,&func,&funcctx);
    2701:     VecDuplicate(f,&fpc);
    2702:     SNESSetFunction(snes->pc,fpc,func,funcctx);
    2703:     SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);
    2704:     SNESSetJacobian(snes->pc,j,jpre,jac,jacctx);
    2705:     SNESGetApplicationContext(snes,&appctx);
    2706:     SNESSetApplicationContext(snes->pc,appctx);
    2707:     VecDestroy(&fpc);

    2709:     /* copy the function pointers over */
    2710:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);

    2712:     /* default to 1 iteration */
    2713:     SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);
    2714:     if (snes->pcside==PC_RIGHT) {
    2715:       SNESSetNormSchedule(snes->pc,SNES_NORM_FINAL_ONLY);
    2716:     } else {
    2717:       SNESSetNormSchedule(snes->pc,SNES_NORM_NONE);
    2718:     }
    2719:     SNESSetFromOptions(snes->pc);

    2721:     /* copy the line search context over */
    2722:     SNESGetLineSearch(snes,&linesearch);
    2723:     SNESGetLineSearch(snes->pc,&pclinesearch);
    2724:     SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
    2725:     SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
    2726:     SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);
    2727:     SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);
    2728:     PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);
    2729:   }
    2730:   if (snes->mf) {
    2731:     SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);
    2732:   }
    2733:   if (snes->ops->usercompute && !snes->user) {
    2734:     (*snes->ops->usercompute)(snes,(void**)&snes->user);
    2735:   }

    2737:   snes->jac_iter = 0;
    2738:   snes->pre_iter = 0;

    2740:   if (snes->ops->setup) {
    2741:     (*snes->ops->setup)(snes);
    2742:   }

    2744:   if (snes->pc && (snes->pcside == PC_LEFT)) {
    2745:     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
    2746:       SNESGetLineSearch(snes,&linesearch);
    2747:       SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);
    2748:     }
    2749:   }

    2751:   snes->setupcalled = PETSC_TRUE;
    2752:   return(0);
    2753: }

    2757: /*@
    2758:    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats

    2760:    Collective on SNES

    2762:    Input Parameter:
    2763: .  snes - iterative context obtained from SNESCreate()

    2765:    Level: intermediate

    2767:    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()

    2769: .keywords: SNES, destroy

    2771: .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
    2772: @*/
    2773: PetscErrorCode  SNESReset(SNES snes)
    2774: {

    2779:   if (snes->ops->userdestroy && snes->user) {
    2780:     (*snes->ops->userdestroy)((void**)&snes->user);
    2781:     snes->user = NULL;
    2782:   }
    2783:   if (snes->pc) {
    2784:     SNESReset(snes->pc);
    2785:   }

    2787:   if (snes->ops->reset) {
    2788:     (*snes->ops->reset)(snes);
    2789:   }
    2790:   if (snes->ksp) {
    2791:     KSPReset(snes->ksp);
    2792:   }

    2794:   if (snes->linesearch) {
    2795:     SNESLineSearchReset(snes->linesearch);
    2796:   }

    2798:   VecDestroy(&snes->vec_rhs);
    2799:   VecDestroy(&snes->vec_sol);
    2800:   VecDestroy(&snes->vec_sol_update);
    2801:   VecDestroy(&snes->vec_func);
    2802:   MatDestroy(&snes->jacobian);
    2803:   MatDestroy(&snes->jacobian_pre);
    2804:   VecDestroyVecs(snes->nwork,&snes->work);
    2805:   VecDestroyVecs(snes->nvwork,&snes->vwork);

    2807:   snes->nwork       = snes->nvwork = 0;
    2808:   snes->setupcalled = PETSC_FALSE;
    2809:   return(0);
    2810: }

    2814: /*@
    2815:    SNESDestroy - Destroys the nonlinear solver context that was created
    2816:    with SNESCreate().

    2818:    Collective on SNES

    2820:    Input Parameter:
    2821: .  snes - the SNES context

    2823:    Level: beginner

    2825: .keywords: SNES, nonlinear, destroy

    2827: .seealso: SNESCreate(), SNESSolve()
    2828: @*/
    2829: PetscErrorCode  SNESDestroy(SNES *snes)
    2830: {

    2834:   if (!*snes) return(0);
    2836:   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; return(0);}

    2838:   SNESReset((*snes));
    2839:   SNESDestroy(&(*snes)->pc);

    2841:   /* if memory was published with SAWs then destroy it */
    2842:   PetscObjectSAWsViewOff((PetscObject)*snes);
    2843:   if ((*snes)->ops->destroy) {(*((*snes))->ops->destroy)((*snes));}

    2845:   DMDestroy(&(*snes)->dm);
    2846:   KSPDestroy(&(*snes)->ksp);
    2847:   SNESLineSearchDestroy(&(*snes)->linesearch);

    2849:   PetscFree((*snes)->kspconvctx);
    2850:   if ((*snes)->ops->convergeddestroy) {
    2851:     (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);
    2852:   }
    2853:   if ((*snes)->conv_malloc) {
    2854:     PetscFree((*snes)->conv_hist);
    2855:     PetscFree((*snes)->conv_hist_its);
    2856:   }
    2857:   SNESMonitorCancel((*snes));
    2858:   PetscHeaderDestroy(snes);
    2859:   return(0);
    2860: }

    2862: /* ----------- Routines to set solver parameters ---------- */

    2866: /*@
    2867:    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.

    2869:    Logically Collective on SNES

    2871:    Input Parameters:
    2872: +  snes - the SNES context
    2873: -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
    2874:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

    2876:    Options Database Keys:
    2877: .    -snes_lag_preconditioner <lag>

    2879:    Notes:
    2880:    The default is 1
    2881:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
    2882:    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use

    2884:    Level: intermediate

    2886: .keywords: SNES, nonlinear, set, convergence, tolerances

    2888: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()

    2890: @*/
    2891: PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
    2892: {
    2895:   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
    2896:   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
    2898:   snes->lagpreconditioner = lag;
    2899:   return(0);
    2900: }

    2904: /*@
    2905:    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does

    2907:    Logically Collective on SNES

    2909:    Input Parameters:
    2910: +  snes - the SNES context
    2911: -  steps - the number of refinements to do, defaults to 0

    2913:    Options Database Keys:
    2914: .    -snes_grid_sequence <steps>

    2916:    Level: intermediate

    2918:    Notes:
    2919:    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.

    2921: .keywords: SNES, nonlinear, set, convergence, tolerances

    2923: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetGridSequence()

    2925: @*/
    2926: PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
    2927: {
    2931:   snes->gridsequence = steps;
    2932:   return(0);
    2933: }

    2937: /*@
    2938:    SNESGetGridSequence - gets the number of steps of grid sequencing that SNES does

    2940:    Logically Collective on SNES

    2942:    Input Parameter:
    2943: .  snes - the SNES context

    2945:    Output Parameter:
    2946: .  steps - the number of refinements to do, defaults to 0

    2948:    Options Database Keys:
    2949: .    -snes_grid_sequence <steps>

    2951:    Level: intermediate

    2953:    Notes:
    2954:    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.

    2956: .keywords: SNES, nonlinear, set, convergence, tolerances

    2958: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetGridSequence()

    2960: @*/
    2961: PetscErrorCode  SNESGetGridSequence(SNES snes,PetscInt *steps)
    2962: {
    2965:   *steps = snes->gridsequence;
    2966:   return(0);
    2967: }

    2971: /*@
    2972:    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt

    2974:    Not Collective

    2976:    Input Parameter:
    2977: .  snes - the SNES context

    2979:    Output Parameter:
    2980: .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
    2981:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

    2983:    Options Database Keys:
    2984: .    -snes_lag_preconditioner <lag>

    2986:    Notes:
    2987:    The default is 1
    2988:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

    2990:    Level: intermediate

    2992: .keywords: SNES, nonlinear, set, convergence, tolerances

    2994: .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()

    2996: @*/
    2997: PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
    2998: {
    3001:   *lag = snes->lagpreconditioner;
    3002:   return(0);
    3003: }

    3007: /*@
    3008:    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
    3009:      often the preconditioner is rebuilt.

    3011:    Logically Collective on SNES

    3013:    Input Parameters:
    3014: +  snes - the SNES context
    3015: -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
    3016:          the Jacobian is built etc. -2 means rebuild at next chance but then never again

    3018:    Options Database Keys:
    3019: .    -snes_lag_jacobian <lag>

    3021:    Notes:
    3022:    The default is 1
    3023:    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
    3024:    If  -1 is used before the very first nonlinear solve the CODE WILL FAIL! because no Jacobian is used, use -2 to indicate you want it recomputed
    3025:    at the next Newton step but never again (unless it is reset to another value)

    3027:    Level: intermediate

    3029: .keywords: SNES, nonlinear, set, convergence, tolerances

    3031: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()

    3033: @*/
    3034: PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
    3035: {
    3038:   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
    3039:   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
    3041:   snes->lagjacobian = lag;
    3042:   return(0);
    3043: }

    3047: /*@
    3048:    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt

    3050:    Not Collective

    3052:    Input Parameter:
    3053: .  snes - the SNES context

    3055:    Output Parameter:
    3056: .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
    3057:          the Jacobian is built etc.

    3059:    Options Database Keys:
    3060: .    -snes_lag_jacobian <lag>

    3062:    Notes:
    3063:    The default is 1
    3064:    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

    3066:    Level: intermediate

    3068: .keywords: SNES, nonlinear, set, convergence, tolerances

    3070: .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()

    3072: @*/
    3073: PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
    3074: {
    3077:   *lag = snes->lagjacobian;
    3078:   return(0);
    3079: }

    3083: /*@
    3084:    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves

    3086:    Logically collective on SNES

    3088:    Input Parameter:
    3089: +  snes - the SNES context
    3090: -   flg - jacobian lagging persists if true

    3092:    Options Database Keys:
    3093: .    -snes_lag_jacobian_persists <flg>

    3095:    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
    3096:    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
    3097:    timesteps may present huge efficiency gains.

    3099:    Level: developer

    3101: .keywords: SNES, nonlinear, lag

    3103: .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()

    3105: @*/
    3106: PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
    3107: {
    3111:   snes->lagjac_persist = flg;
    3112:   return(0);
    3113: }

    3117: /*@
    3118:    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves

    3120:    Logically Collective on SNES

    3122:    Input Parameter:
    3123: +  snes - the SNES context
    3124: -   flg - preconditioner lagging persists if true

    3126:    Options Database Keys:
    3127: .    -snes_lag_jacobian_persists <flg>

    3129:    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
    3130:    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
    3131:    several timesteps may present huge efficiency gains.

    3133:    Level: developer

    3135: .keywords: SNES, nonlinear, lag

    3137: .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()

    3139: @*/
    3140: PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
    3141: {
    3145:   snes->lagpre_persist = flg;
    3146:   return(0);
    3147: }

    3151: /*@
    3152:    SNESSetTolerances - Sets various parameters used in convergence tests.

    3154:    Logically Collective on SNES

    3156:    Input Parameters:
    3157: +  snes - the SNES context
    3158: .  abstol - absolute convergence tolerance
    3159: .  rtol - relative convergence tolerance
    3160: .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
    3161: .  maxit - maximum number of iterations
    3162: -  maxf - maximum number of function evaluations

    3164:    Options Database Keys:
    3165: +    -snes_atol <abstol> - Sets abstol
    3166: .    -snes_rtol <rtol> - Sets rtol
    3167: .    -snes_stol <stol> - Sets stol
    3168: .    -snes_max_it <maxit> - Sets maxit
    3169: -    -snes_max_funcs <maxf> - Sets maxf

    3171:    Notes:
    3172:    The default maximum number of iterations is 50.
    3173:    The default maximum number of function evaluations is 1000.

    3175:    Level: intermediate

    3177: .keywords: SNES, nonlinear, set, convergence, tolerances

    3179: .seealso: SNESSetTrustRegionTolerance()
    3180: @*/
    3181: PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
    3182: {

    3191:   if (abstol != PETSC_DEFAULT) {
    3192:     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol);
    3193:     snes->abstol = abstol;
    3194:   }
    3195:   if (rtol != PETSC_DEFAULT) {
    3196:     if (rtol < 0.0 || 1.0 <= rtol) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Relative tolerance %g must be non-negative and less than 1.0",(double)rtol);
    3197:     snes->rtol = rtol;
    3198:   }
    3199:   if (stol != PETSC_DEFAULT) {
    3200:     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol);
    3201:     snes->stol = stol;
    3202:   }
    3203:   if (maxit != PETSC_DEFAULT) {
    3204:     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
    3205:     snes->max_its = maxit;
    3206:   }
    3207:   if (maxf != PETSC_DEFAULT) {
    3208:     if (maxf < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
    3209:     snes->max_funcs = maxf;
    3210:   }
    3211:   snes->tolerancesset = PETSC_TRUE;
    3212:   return(0);
    3213: }

    3217: /*@
    3218:    SNESGetTolerances - Gets various parameters used in convergence tests.

    3220:    Not Collective

    3222:    Input Parameters:
    3223: +  snes - the SNES context
    3224: .  atol - absolute convergence tolerance
    3225: .  rtol - relative convergence tolerance
    3226: .  stol -  convergence tolerance in terms of the norm
    3227:            of the change in the solution between steps
    3228: .  maxit - maximum number of iterations
    3229: -  maxf - maximum number of function evaluations

    3231:    Notes:
    3232:    The user can specify NULL for any parameter that is not needed.

    3234:    Level: intermediate

    3236: .keywords: SNES, nonlinear, get, convergence, tolerances

    3238: .seealso: SNESSetTolerances()
    3239: @*/
    3240: PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
    3241: {
    3244:   if (atol)  *atol  = snes->abstol;
    3245:   if (rtol)  *rtol  = snes->rtol;
    3246:   if (stol)  *stol  = snes->stol;
    3247:   if (maxit) *maxit = snes->max_its;
    3248:   if (maxf)  *maxf  = snes->max_funcs;
    3249:   return(0);
    3250: }

    3254: /*@
    3255:    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.

    3257:    Logically Collective on SNES

    3259:    Input Parameters:
    3260: +  snes - the SNES context
    3261: -  tol - tolerance

    3263:    Options Database Key:
    3264: .  -snes_trtol <tol> - Sets tol

    3266:    Level: intermediate

    3268: .keywords: SNES, nonlinear, set, trust region, tolerance

    3270: .seealso: SNESSetTolerances()
    3271: @*/
    3272: PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
    3273: {
    3277:   snes->deltatol = tol;
    3278:   return(0);
    3279: }

    3281: /*
    3282:    Duplicate the lg monitors for SNES from KSP; for some reason with
    3283:    dynamic libraries things don't work under Sun4 if we just use
    3284:    macros instead of functions
    3285: */
    3288: PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
    3289: {

    3294:   KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);
    3295:   return(0);
    3296: }

    3300: PetscErrorCode  SNESMonitorLGCreate(MPI_Comm comm,const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *lgctx)
    3301: {

    3305:   KSPMonitorLGResidualNormCreate(comm,host,label,x,y,m,n,lgctx);
    3306:   return(0);
    3307: }

    3309: PETSC_INTERN PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);

    3313: PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
    3314: {
    3315:   PetscDrawLG      lg;
    3316:   PetscErrorCode   ierr;
    3317:   PetscReal        x,y,per;
    3318:   PetscViewer      v = (PetscViewer)monctx;
    3319:   static PetscReal prev; /* should be in the context */
    3320:   PetscDraw        draw;

    3324:   PetscViewerDrawGetDrawLG(v,0,&lg);
    3325:   if (!n) {PetscDrawLGReset(lg);}
    3326:   PetscDrawLGGetDraw(lg,&draw);
    3327:   PetscDrawSetTitle(draw,"Residual norm");
    3328:   x    = (PetscReal)n;
    3329:   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
    3330:   else y = -15.0;
    3331:   PetscDrawLGAddPoint(lg,&x,&y);
    3332:   if (n < 20 || !(n % 5) || snes->reason) {
    3333:     PetscDrawLGDraw(lg);
    3334:     PetscDrawLGSave(lg);
    3335:   }

    3337:   PetscViewerDrawGetDrawLG(v,1,&lg);
    3338:   if (!n) {PetscDrawLGReset(lg);}
    3339:   PetscDrawLGGetDraw(lg,&draw);
    3340:   PetscDrawSetTitle(draw,"% elemts > .2*max elemt");
    3341:    SNESMonitorRange_Private(snes,n,&per);
    3342:   x    = (PetscReal)n;
    3343:   y    = 100.0*per;
    3344:   PetscDrawLGAddPoint(lg,&x,&y);
    3345:   if (n < 20 || !(n % 5) || snes->reason) {
    3346:     PetscDrawLGDraw(lg);
    3347:     PetscDrawLGSave(lg);
    3348:   }

    3350:   PetscViewerDrawGetDrawLG(v,2,&lg);
    3351:   if (!n) {prev = rnorm;PetscDrawLGReset(lg);}
    3352:   PetscDrawLGGetDraw(lg,&draw);
    3353:   PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");
    3354:   x    = (PetscReal)n;
    3355:   y    = (prev - rnorm)/prev;
    3356:   PetscDrawLGAddPoint(lg,&x,&y);
    3357:   if (n < 20 || !(n % 5) || snes->reason) {
    3358:     PetscDrawLGDraw(lg);
    3359:     PetscDrawLGSave(lg);
    3360:   }

    3362:   PetscViewerDrawGetDrawLG(v,3,&lg);
    3363:   if (!n) {PetscDrawLGReset(lg);}
    3364:   PetscDrawLGGetDraw(lg,&draw);
    3365:   PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");
    3366:   x    = (PetscReal)n;
    3367:   y    = (prev - rnorm)/(prev*per);
    3368:   if (n > 2) { /*skip initial crazy value */
    3369:     PetscDrawLGAddPoint(lg,&x,&y);
    3370:   }
    3371:   if (n < 20 || !(n % 5) || snes->reason) {
    3372:     PetscDrawLGDraw(lg);
    3373:     PetscDrawLGSave(lg);
    3374:   }
    3375:   prev = rnorm;
    3376:   return(0);
    3377: }

    3381: /*@
    3382:    SNESMonitor - runs the user provided monitor routines, if they exist

    3384:    Collective on SNES

    3386:    Input Parameters:
    3387: +  snes - nonlinear solver context obtained from SNESCreate()
    3388: .  iter - iteration number
    3389: -  rnorm - relative norm of the residual

    3391:    Notes:
    3392:    This routine is called by the SNES implementations.
    3393:    It does not typically need to be called by the user.

    3395:    Level: developer

    3397: .seealso: SNESMonitorSet()
    3398: @*/
    3399: PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
    3400: {
    3402:   PetscInt       i,n = snes->numbermonitors;

    3405:   VecLockPush(snes->vec_sol);
    3406:   for (i=0; i<n; i++) {
    3407:     (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);
    3408:   }
    3409:   VecLockPop(snes->vec_sol);
    3410:   return(0);
    3411: }

    3413: /* ------------ Routines to set performance monitoring options ----------- */

    3415: /*MC
    3416:     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver

    3418:      Synopsis:
    3419:      #include <petscsnes.h>
    3420: $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)

    3422: +    snes - the SNES context
    3423: .    its - iteration number
    3424: .    norm - 2-norm function value (may be estimated)
    3425: -    mctx - [optional] monitoring context

    3427:    Level: advanced

    3429: .seealso:   SNESMonitorSet(), SNESMonitorGet()
    3430: M*/

    3434: /*@C
    3435:    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
    3436:    iteration of the nonlinear solver to display the iteration's
    3437:    progress.

    3439:    Logically Collective on SNES

    3441:    Input Parameters:
    3442: +  snes - the SNES context
    3443: .  f - the monitor function, see SNESMonitorFunction for the calling sequence
    3444: .  mctx - [optional] user-defined context for private data for the
    3445:           monitor routine (use NULL if no context is desired)
    3446: -  monitordestroy - [optional] routine that frees monitor context
    3447:           (may be NULL)

    3449:    Options Database Keys:
    3450: +    -snes_monitor        - sets SNESMonitorDefault()
    3451: .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
    3452:                             uses SNESMonitorLGCreate()
    3453: -    -snes_monitor_cancel - cancels all monitors that have
    3454:                             been hardwired into a code by
    3455:                             calls to SNESMonitorSet(), but
    3456:                             does not cancel those set via
    3457:                             the options database.

    3459:    Notes:
    3460:    Several different monitoring routines may be set by calling
    3461:    SNESMonitorSet() multiple times; all will be called in the
    3462:    order in which they were set.

    3464:    Fortran notes: Only a single monitor function can be set for each SNES object

    3466:    Level: intermediate

    3468: .keywords: SNES, nonlinear, set, monitor

    3470: .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
    3471: @*/
    3472: PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
    3473: {
    3474:   PetscInt       i;
    3476:   PetscBool      identical;

    3480:   for (i=0; i<snes->numbermonitors;i++) {
    3481:     PetscMonitorCompare((PetscErrorCode (*)(void))f,mctx,monitordestroy,(PetscErrorCode (*)(void))snes->monitor[i],snes->monitorcontext[i],snes->monitordestroy[i],&identical);
    3482:     if (identical) return(0);
    3483:   }
    3484:   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
    3485:   snes->monitor[snes->numbermonitors]          = f;
    3486:   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
    3487:   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
    3488:   return(0);
    3489: }

    3493: /*@
    3494:    SNESMonitorCancel - Clears all the monitor functions for a SNES object.

    3496:    Logically Collective on SNES

    3498:    Input Parameters:
    3499: .  snes - the SNES context

    3501:    Options Database Key:
    3502: .  -snes_monitor_cancel - cancels all monitors that have been hardwired
    3503:     into a code by calls to SNESMonitorSet(), but does not cancel those
    3504:     set via the options database

    3506:    Notes:
    3507:    There is no way to clear one specific monitor from a SNES object.

    3509:    Level: intermediate

    3511: .keywords: SNES, nonlinear, set, monitor

    3513: .seealso: SNESMonitorDefault(), SNESMonitorSet()
    3514: @*/
    3515: PetscErrorCode  SNESMonitorCancel(SNES snes)
    3516: {
    3518:   PetscInt       i;

    3522:   for (i=0; i<snes->numbermonitors; i++) {
    3523:     if (snes->monitordestroy[i]) {
    3524:       (*snes->monitordestroy[i])(&snes->monitorcontext[i]);
    3525:     }
    3526:   }
    3527:   snes->numbermonitors = 0;
    3528:   return(0);
    3529: }

    3531: /*MC
    3532:     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver

    3534:      Synopsis:
    3535:      #include <petscsnes.h>
    3536: $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)

    3538: +    snes - the SNES context
    3539: .    it - current iteration (0 is the first and is before any Newton step)
    3540: .    cctx - [optional] convergence context
    3541: .    reason - reason for convergence/divergence
    3542: .    xnorm - 2-norm of current iterate
    3543: .    gnorm - 2-norm of current step
    3544: -    f - 2-norm of function

    3546:    Level: intermediate

    3548: .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
    3549: M*/

    3553: /*@C
    3554:    SNESSetConvergenceTest - Sets the function that is to be used
    3555:    to test for convergence of the nonlinear iterative solution.

    3557:    Logically Collective on SNES

    3559:    Input Parameters:
    3560: +  snes - the SNES context
    3561: .  SNESConvergenceTestFunction - routine to test for convergence
    3562: .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
    3563: -  destroy - [optional] destructor for the context (may be NULL; NULL_FUNCTION in Fortran)

    3565:    Level: advanced

    3567: .keywords: SNES, nonlinear, set, convergence, test

    3569: .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
    3570: @*/
    3571: PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
    3572: {

    3577:   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
    3578:   if (snes->ops->convergeddestroy) {
    3579:     (*snes->ops->convergeddestroy)(snes->cnvP);
    3580:   }
    3581:   snes->ops->converged        = SNESConvergenceTestFunction;
    3582:   snes->ops->convergeddestroy = destroy;
    3583:   snes->cnvP                  = cctx;
    3584:   return(0);
    3585: }

    3589: /*@
    3590:    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.

    3592:    Not Collective

    3594:    Input Parameter:
    3595: .  snes - the SNES context

    3597:    Output Parameter:
    3598: .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
    3599:             manual pages for the individual convergence tests for complete lists

    3601:    Level: intermediate

    3603:    Notes: Can only be called after the call the SNESSolve() is complete.

    3605: .keywords: SNES, nonlinear, set, convergence, test

    3607: .seealso: SNESSetConvergenceTest(), SNESSetConvergedReason(), SNESConvergedReason
    3608: @*/
    3609: PetscErrorCode SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
    3610: {
    3614:   *reason = snes->reason;
    3615:   return(0);
    3616: }

    3620: /*@
    3621:    SNESSetConvergedReason - Sets the reason the SNES iteration was stopped.

    3623:    Not Collective

    3625:    Input Parameters:
    3626: +  snes - the SNES context
    3627: -  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
    3628:             manual pages for the individual convergence tests for complete lists

    3630:    Level: intermediate

    3632: .keywords: SNES, nonlinear, set, convergence, test
    3633: .seealso: SNESGetConvergedReason(), SNESSetConvergenceTest(), SNESConvergedReason
    3634: @*/
    3635: PetscErrorCode SNESSetConvergedReason(SNES snes,SNESConvergedReason reason)
    3636: {
    3639:   snes->reason = reason;
    3640:   return(0);
    3641: }

    3645: /*@
    3646:    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.

    3648:    Logically Collective on SNES

    3650:    Input Parameters:
    3651: +  snes - iterative context obtained from SNESCreate()
    3652: .  a   - array to hold history, this array will contain the function norms computed at each step
    3653: .  its - integer array holds the number of linear iterations for each solve.
    3654: .  na  - size of a and its
    3655: -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
    3656:            else it continues storing new values for new nonlinear solves after the old ones

    3658:    Notes:
    3659:    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
    3660:    default array of length 10000 is allocated.

    3662:    This routine is useful, e.g., when running a code for purposes
    3663:    of accurate performance monitoring, when no I/O should be done
    3664:    during the section of code that is being timed.

    3666:    Level: intermediate

    3668: .keywords: SNES, set, convergence, history

    3670: .seealso: SNESGetConvergenceHistory()

    3672: @*/
    3673: PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
    3674: {

    3681:   if (!a) {
    3682:     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
    3683:     PetscCalloc1(na,&a);
    3684:     PetscCalloc1(na,&its);

    3686:     snes->conv_malloc = PETSC_TRUE;
    3687:   }
    3688:   snes->conv_hist       = a;
    3689:   snes->conv_hist_its   = its;
    3690:   snes->conv_hist_max   = na;
    3691:   snes->conv_hist_len   = 0;
    3692:   snes->conv_hist_reset = reset;
    3693:   return(0);
    3694: }

    3696: #if defined(PETSC_HAVE_MATLAB_ENGINE)
    3697: #include <engine.h>   /* MATLAB include file */
    3698: #include <mex.h>      /* MATLAB include file */

    3702: PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
    3703: {
    3704:   mxArray   *mat;
    3705:   PetscInt  i;
    3706:   PetscReal *ar;

    3709:   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
    3710:   ar  = (PetscReal*) mxGetData(mat);
    3711:   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
    3712:   PetscFunctionReturn(mat);
    3713: }
    3714: #endif

    3718: /*@C
    3719:    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.

    3721:    Not Collective

    3723:    Input Parameter:
    3724: .  snes - iterative context obtained from SNESCreate()

    3726:    Output Parameters:
    3727: .  a   - array to hold history
    3728: .  its - integer array holds the number of linear iterations (or
    3729:          negative if not converged) for each solve.
    3730: -  na  - size of a and its

    3732:    Notes:
    3733:     The calling sequence for this routine in Fortran is
    3734: $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)

    3736:    This routine is useful, e.g., when running a code for purposes
    3737:    of accurate performance monitoring, when no I/O should be done
    3738:    during the section of code that is being timed.

    3740:    Level: intermediate

    3742: .keywords: SNES, get, convergence, history

    3744: .seealso: SNESSetConvergencHistory()

    3746: @*/
    3747: PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
    3748: {
    3751:   if (a)   *a   = snes->conv_hist;
    3752:   if (its) *its = snes->conv_hist_its;
    3753:   if (na)  *na  = snes->conv_hist_len;
    3754:   return(0);
    3755: }

    3759: /*@C
    3760:   SNESSetUpdate - Sets the general-purpose update function called
    3761:   at the beginning of every iteration of the nonlinear solve. Specifically
    3762:   it is called just before the Jacobian is "evaluated".

    3764:   Logically Collective on SNES

    3766:   Input Parameters:
    3767: . snes - The nonlinear solver context
    3768: . func - The function

    3770:   Calling sequence of func:
    3771: . func (SNES snes, PetscInt step);

    3773: . step - The current step of the iteration

    3775:   Level: advanced

    3777:   Note: This is NOT what one uses to update the ghost points before a function evaluation, that should be done at the beginning of your FormFunction()
    3778:         This is not used by most users.

    3780: .keywords: SNES, update

    3782: .seealso SNESSetJacobian(), SNESSolve()
    3783: @*/
    3784: PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
    3785: {
    3788:   snes->ops->update = func;
    3789:   return(0);
    3790: }

    3794: /*
    3795:    SNESScaleStep_Private - Scales a step so that its length is less than the
    3796:    positive parameter delta.

    3798:     Input Parameters:
    3799: +   snes - the SNES context
    3800: .   y - approximate solution of linear system
    3801: .   fnorm - 2-norm of current function
    3802: -   delta - trust region size

    3804:     Output Parameters:
    3805: +   gpnorm - predicted function norm at the new point, assuming local
    3806:     linearization.  The value is zero if the step lies within the trust
    3807:     region, and exceeds zero otherwise.
    3808: -   ynorm - 2-norm of the step

    3810:     Note:
    3811:     For non-trust region methods such as SNESNEWTONLS, the parameter delta
    3812:     is set to be the maximum allowable step size.

    3814: .keywords: SNES, nonlinear, scale, step
    3815: */
    3816: PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
    3817: {
    3818:   PetscReal      nrm;
    3819:   PetscScalar    cnorm;

    3827:   VecNorm(y,NORM_2,&nrm);
    3828:   if (nrm > *delta) {
    3829:     nrm     = *delta/nrm;
    3830:     *gpnorm = (1.0 - nrm)*(*fnorm);
    3831:     cnorm   = nrm;
    3832:     VecScale(y,cnorm);
    3833:     *ynorm  = *delta;
    3834:   } else {
    3835:     *gpnorm = 0.0;
    3836:     *ynorm  = nrm;
    3837:   }
    3838:   return(0);
    3839: }

    3843: /*@
    3844:    SNESReasonView - Displays the reason a SNES solve converged or diverged to a viewer

    3846:    Collective on SNES

    3848:    Parameter:
    3849: +  snes - iterative context obtained from SNESCreate()
    3850: -  viewer - the viewer to display the reason

    3853:    Options Database Keys:
    3854: .  -snes_converged_reason - print reason for converged or diverged, also prints number of iterations

    3856:    Level: beginner

    3858: .keywords: SNES, solve, linear system

    3860: .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault()

    3862: @*/
    3863: PetscErrorCode  SNESReasonView(SNES snes,PetscViewer viewer)
    3864: {
    3866:   PetscBool      isAscii;

    3869:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isAscii);
    3870:   if (isAscii) {
    3871:     PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);
    3872:     if (snes->reason > 0) {
    3873:       if (((PetscObject) snes)->prefix) {
    3874:         PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve converged due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);
    3875:       } else {
    3876:         PetscViewerASCIIPrintf(viewer,"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);
    3877:       }
    3878:     } else {
    3879:       if (((PetscObject) snes)->prefix) {
    3880:         PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve did not converge due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);
    3881:       } else {
    3882:         PetscViewerASCIIPrintf(viewer,"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);
    3883:       }
    3884:     }
    3885:     PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);
    3886:   }
    3887:   return(0);
    3888: }

    3892: /*@C
    3893:   SNESReasonViewFromOptions - Processes command line options to determine if/how a SNESReason is to be viewed.

    3895:   Collective on SNES

    3897:   Input Parameters:
    3898: . snes   - the SNES object

    3900:   Level: intermediate

    3902: @*/
    3903: PetscErrorCode SNESReasonViewFromOptions(SNES snes)
    3904: {
    3905:   PetscErrorCode    ierr;
    3906:   PetscViewer       viewer;
    3907:   PetscBool         flg;
    3908:   static PetscBool  incall = PETSC_FALSE;
    3909:   PetscViewerFormat format;

    3912:   if (incall) return(0);
    3913:   incall = PETSC_TRUE;
    3914:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_converged_reason",&viewer,&format,&flg);
    3915:   if (flg) {
    3916:     PetscViewerPushFormat(viewer,format);
    3917:     SNESReasonView(snes,viewer);
    3918:     PetscViewerPopFormat(viewer);
    3919:     PetscViewerDestroy(&viewer);
    3920:   }
    3921:   incall = PETSC_FALSE;
    3922:   return(0);
    3923: }

    3927: /*@C
    3928:    SNESSolve - Solves a nonlinear system F(x) = b.
    3929:    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().

    3931:    Collective on SNES

    3933:    Input Parameters:
    3934: +  snes - the SNES context
    3935: .  b - the constant part of the equation F(x) = b, or NULL to use zero.
    3936: -  x - the solution vector.

    3938:    Notes:
    3939:    The user should initialize the vector,x, with the initial guess
    3940:    for the nonlinear solve prior to calling SNESSolve.  In particular,
    3941:    to employ an initial guess of zero, the user should explicitly set
    3942:    this vector to zero by calling VecSet().

    3944:    Level: beginner

    3946: .keywords: SNES, nonlinear, solve

    3948: .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
    3949: @*/
    3950: PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
    3951: {
    3952:   PetscErrorCode    ierr;
    3953:   PetscBool         flg;
    3954:   PetscInt          grid;
    3955:   Vec               xcreated = NULL;
    3956:   DM                dm;

    3965:   if (!x) {
    3966:     SNESGetDM(snes,&dm);
    3967:     DMCreateGlobalVector(dm,&xcreated);
    3968:     x    = xcreated;
    3969:   }
    3970:   SNESViewFromOptions(snes,NULL,"-snes_view_pre");

    3972:   for (grid=0; grid<snes->gridsequence; grid++) {PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));}
    3973:   for (grid=0; grid<snes->gridsequence+1; grid++) {

    3975:     /* set solution vector */
    3976:     if (!grid) {PetscObjectReference((PetscObject)x);}
    3977:     VecDestroy(&snes->vec_sol);
    3978:     snes->vec_sol = x;
    3979:     SNESGetDM(snes,&dm);

    3981:     /* set affine vector if provided */
    3982:     if (b) { PetscObjectReference((PetscObject)b); }
    3983:     VecDestroy(&snes->vec_rhs);
    3984:     snes->vec_rhs = b;

    3986:     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
    3987:     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
    3988:     if (!snes->vec_sol_update /* && snes->vec_sol */) {
    3989:       VecDuplicate(snes->vec_sol,&snes->vec_sol_update);
    3990:       PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);
    3991:     }
    3992:     DMShellSetGlobalVector(dm,snes->vec_sol);
    3993:     SNESSetUp(snes);

    3995:     if (!grid) {
    3996:       if (snes->ops->computeinitialguess) {
    3997:         (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);
    3998:       }
    3999:     }

    4001:     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
    4002:     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}

    4004:     PetscLogEventBegin(SNES_Solve,snes,0,0,0);
    4005:     (*snes->ops->solve)(snes);
    4006:     PetscLogEventEnd(SNES_Solve,snes,0,0,0);
    4007:     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
    4008:     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */

    4010:     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
    4011:     if (snes->lagpre_persist) snes->pre_iter += snes->iter;

    4013:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_test_local_min",NULL,NULL,&flg);
    4014:     if (flg && !PetscPreLoadingOn) { SNESTestLocalMin(snes); }
    4015:     SNESReasonViewFromOptions(snes);

    4017:     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
    4018:     if (snes->reason < 0) break;
    4019:     if (grid <  snes->gridsequence) {
    4020:       DM  fine;
    4021:       Vec xnew;
    4022:       Mat interp;

    4024:       DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);
    4025:       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
    4026:       DMCreateInterpolation(snes->dm,fine,&interp,NULL);
    4027:       DMCreateGlobalVector(fine,&xnew);
    4028:       MatInterpolate(interp,x,xnew);
    4029:       DMInterpolate(snes->dm,interp,fine);
    4030:       MatDestroy(&interp);
    4031:       x    = xnew;

    4033:       SNESReset(snes);
    4034:       SNESSetDM(snes,fine);
    4035:       DMDestroy(&fine);
    4036:       PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));
    4037:     }
    4038:   }
    4039:   SNESViewFromOptions(snes,NULL,"-snes_view");
    4040:   VecViewFromOptions(snes->vec_sol,(PetscObject)snes,"-snes_view_solution");

    4042:   VecDestroy(&xcreated);
    4043:   PetscObjectSAWsBlock((PetscObject)snes);
    4044:   return(0);
    4045: }

    4047: /* --------- Internal routines for SNES Package --------- */

    4051: /*@C
    4052:    SNESSetType - Sets the method for the nonlinear solver.

    4054:    Collective on SNES

    4056:    Input Parameters:
    4057: +  snes - the SNES context
    4058: -  type - a known method

    4060:    Options Database Key:
    4061: .  -snes_type <type> - Sets the method; use -help for a list
    4062:    of available methods (for instance, newtonls or newtontr)

    4064:    Notes:
    4065:    See "petsc/include/petscsnes.h" for available methods (for instance)
    4066: +    SNESNEWTONLS - Newton's method with line search
    4067:      (systems of nonlinear equations)
    4068: .    SNESNEWTONTR - Newton's method with trust region
    4069:      (systems of nonlinear equations)

    4071:   Normally, it is best to use the SNESSetFromOptions() command and then
    4072:   set the SNES solver type from the options database rather than by using
    4073:   this routine.  Using the options database provides the user with
    4074:   maximum flexibility in evaluating the many nonlinear solvers.
    4075:   The SNESSetType() routine is provided for those situations where it
    4076:   is necessary to set the nonlinear solver independently of the command
    4077:   line or options database.  This might be the case, for example, when
    4078:   the choice of solver changes during the execution of the program,
    4079:   and the user's application is taking responsibility for choosing the
    4080:   appropriate method.

    4082:     Developer Notes: SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
    4083:     the constructor in that list and calls it to create the spexific object.

    4085:   Level: intermediate

    4087: .keywords: SNES, set, type

    4089: .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()

    4091: @*/
    4092: PetscErrorCode  SNESSetType(SNES snes,SNESType type)
    4093: {
    4094:   PetscErrorCode ierr,(*r)(SNES);
    4095:   PetscBool      match;

    4101:   PetscObjectTypeCompare((PetscObject)snes,type,&match);
    4102:   if (match) return(0);

    4104:    PetscFunctionListFind(SNESList,type,&r);
    4105:   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
    4106:   /* Destroy the previous private SNES context */
    4107:   if (snes->ops->destroy) {
    4108:     (*(snes)->ops->destroy)(snes);
    4109:     snes->ops->destroy = NULL;
    4110:   }
    4111:   /* Reinitialize function pointers in SNESOps structure */
    4112:   snes->ops->setup          = 0;
    4113:   snes->ops->solve          = 0;
    4114:   snes->ops->view           = 0;
    4115:   snes->ops->setfromoptions = 0;
    4116:   snes->ops->destroy        = 0;
    4117:   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
    4118:   snes->setupcalled = PETSC_FALSE;

    4120:   PetscObjectChangeTypeName((PetscObject)snes,type);
    4121:   (*r)(snes);
    4122:   return(0);
    4123: }

    4127: /*@C
    4128:    SNESGetType - Gets the SNES method type and name (as a string).

    4130:    Not Collective

    4132:    Input Parameter:
    4133: .  snes - nonlinear solver context

    4135:    Output Parameter:
    4136: .  type - SNES method (a character string)

    4138:    Level: intermediate

    4140: .keywords: SNES, nonlinear, get, type, name
    4141: @*/
    4142: PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
    4143: {
    4147:   *type = ((PetscObject)snes)->type_name;
    4148:   return(0);
    4149: }

    4153: /*@
    4154:   SNESSetSolution - Sets the solution vector for use by the SNES routines.

    4156:   Logically Collective on SNES and Vec

    4158:   Input Parameters:
    4159: + snes - the SNES context obtained from SNESCreate()
    4160: - u    - the solution vector

    4162:   Level: beginner

    4164: .keywords: SNES, set, solution
    4165: @*/
    4166: PetscErrorCode SNESSetSolution(SNES snes, Vec u)
    4167: {
    4168:   DM             dm;

    4174:   PetscObjectReference((PetscObject) u);
    4175:   VecDestroy(&snes->vec_sol);

    4177:   snes->vec_sol = u;

    4179:   SNESGetDM(snes, &dm);
    4180:   DMShellSetGlobalVector(dm, u);
    4181:   return(0);
    4182: }

    4186: /*@
    4187:    SNESGetSolution - Returns the vector where the approximate solution is
    4188:    stored. This is the fine grid solution when using SNESSetGridSequence().

    4190:    Not Collective, but Vec is parallel if SNES is parallel

    4192:    Input Parameter:
    4193: .  snes - the SNES context

    4195:    Output Parameter:
    4196: .  x - the solution

    4198:    Level: intermediate

    4200: .keywords: SNES, nonlinear, get, solution

    4202: .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
    4203: @*/
    4204: PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
    4205: {
    4209:   *x = snes->vec_sol;
    4210:   return(0);
    4211: }

    4215: /*@
    4216:    SNESGetSolutionUpdate - Returns the vector where the solution update is
    4217:    stored.

    4219:    Not Collective, but Vec is parallel if SNES is parallel

    4221:    Input Parameter:
    4222: .  snes - the SNES context

    4224:    Output Parameter:
    4225: .  x - the solution update

    4227:    Level: advanced

    4229: .keywords: SNES, nonlinear, get, solution, update

    4231: .seealso: SNESGetSolution(), SNESGetFunction()
    4232: @*/
    4233: PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
    4234: {
    4238:   *x = snes->vec_sol_update;
    4239:   return(0);
    4240: }

    4244: /*@C
    4245:    SNESGetFunction - Returns the vector where the function is stored.

    4247:    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.

    4249:    Input Parameter:
    4250: .  snes - the SNES context

    4252:    Output Parameter:
    4253: +  r - the vector that is used to store residuals (or NULL if you don't want it)
    4254: .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
    4255: -  ctx - the function context (or NULL if you don't want it)

    4257:    Level: advanced

    4259: .keywords: SNES, nonlinear, get, function

    4261: .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
    4262: @*/
    4263: PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
    4264: {
    4266:   DM             dm;

    4270:   if (r) {
    4271:     if (!snes->vec_func) {
    4272:       if (snes->vec_rhs) {
    4273:         VecDuplicate(snes->vec_rhs,&snes->vec_func);
    4274:       } else if (snes->vec_sol) {
    4275:         VecDuplicate(snes->vec_sol,&snes->vec_func);
    4276:       } else if (snes->dm) {
    4277:         DMCreateGlobalVector(snes->dm,&snes->vec_func);
    4278:       }
    4279:     }
    4280:     *r = snes->vec_func;
    4281:   }
    4282:   SNESGetDM(snes,&dm);
    4283:   DMSNESGetFunction(dm,f,ctx);
    4284:   return(0);
    4285: }

    4287: /*@C
    4288:    SNESGetNGS - Returns the NGS function and context.

    4290:    Input Parameter:
    4291: .  snes - the SNES context

    4293:    Output Parameter:
    4294: +  f - the function (or NULL) see SNESNGSFunction for details
    4295: -  ctx    - the function context (or NULL)

    4297:    Level: advanced

    4299: .keywords: SNES, nonlinear, get, function

    4301: .seealso: SNESSetNGS(), SNESGetFunction()
    4302: @*/

    4306: PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
    4307: {
    4309:   DM             dm;

    4313:   SNESGetDM(snes,&dm);
    4314:   DMSNESGetNGS(dm,f,ctx);
    4315:   return(0);
    4316: }

    4320: /*@C
    4321:    SNESSetOptionsPrefix - Sets the prefix used for searching for all
    4322:    SNES options in the database.

    4324:    Logically Collective on SNES

    4326:    Input Parameter:
    4327: +  snes - the SNES context
    4328: -  prefix - the prefix to prepend to all option names

    4330:    Notes:
    4331:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    4332:    The first character of all runtime options is AUTOMATICALLY the hyphen.

    4334:    Level: advanced

    4336: .keywords: SNES, set, options, prefix, database

    4338: .seealso: SNESSetFromOptions()
    4339: @*/
    4340: PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
    4341: {

    4346:   PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);
    4347:   if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
    4348:   if (snes->linesearch) {
    4349:     SNESGetLineSearch(snes,&snes->linesearch);
    4350:     PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);
    4351:   }
    4352:   KSPSetOptionsPrefix(snes->ksp,prefix);
    4353:   return(0);
    4354: }

    4358: /*@C
    4359:    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
    4360:    SNES options in the database.

    4362:    Logically Collective on SNES

    4364:    Input Parameters:
    4365: +  snes - the SNES context
    4366: -  prefix - the prefix to prepend to all option names

    4368:    Notes:
    4369:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    4370:    The first character of all runtime options is AUTOMATICALLY the hyphen.

    4372:    Level: advanced

    4374: .keywords: SNES, append, options, prefix, database

    4376: .seealso: SNESGetOptionsPrefix()
    4377: @*/
    4378: PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
    4379: {

    4384:   PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);
    4385:   if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
    4386:   if (snes->linesearch) {
    4387:     SNESGetLineSearch(snes,&snes->linesearch);
    4388:     PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);
    4389:   }
    4390:   KSPAppendOptionsPrefix(snes->ksp,prefix);
    4391:   return(0);
    4392: }

    4396: /*@C
    4397:    SNESGetOptionsPrefix - Sets the prefix used for searching for all
    4398:    SNES options in the database.

    4400:    Not Collective

    4402:    Input Parameter:
    4403: .  snes - the SNES context

    4405:    Output Parameter:
    4406: .  prefix - pointer to the prefix string used

    4408:    Notes: On the fortran side, the user should pass in a string 'prefix' of
    4409:    sufficient length to hold the prefix.

    4411:    Level: advanced

    4413: .keywords: SNES, get, options, prefix, database

    4415: .seealso: SNESAppendOptionsPrefix()
    4416: @*/
    4417: PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
    4418: {

    4423:   PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);
    4424:   return(0);
    4425: }

    4430: /*@C
    4431:   SNESRegister - Adds a method to the nonlinear solver package.

    4433:    Not collective

    4435:    Input Parameters:
    4436: +  name_solver - name of a new user-defined solver
    4437: -  routine_create - routine to create method context

    4439:    Notes:
    4440:    SNESRegister() may be called multiple times to add several user-defined solvers.

    4442:    Sample usage:
    4443: .vb
    4444:    SNESRegister("my_solver",MySolverCreate);
    4445: .ve

    4447:    Then, your solver can be chosen with the procedural interface via
    4448: $     SNESSetType(snes,"my_solver")
    4449:    or at runtime via the option
    4450: $     -snes_type my_solver

    4452:    Level: advanced

    4454:     Note: If your function is not being put into a shared library then use SNESRegister() instead

    4456: .keywords: SNES, nonlinear, register

    4458: .seealso: SNESRegisterAll(), SNESRegisterDestroy()

    4460:   Level: advanced
    4461: @*/
    4462: PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
    4463: {

    4467:   PetscFunctionListAdd(&SNESList,sname,function);
    4468:   return(0);
    4469: }

    4473: PetscErrorCode  SNESTestLocalMin(SNES snes)
    4474: {
    4476:   PetscInt       N,i,j;
    4477:   Vec            u,uh,fh;
    4478:   PetscScalar    value;
    4479:   PetscReal      norm;

    4482:   SNESGetSolution(snes,&u);
    4483:   VecDuplicate(u,&uh);
    4484:   VecDuplicate(u,&fh);

    4486:   /* currently only works for sequential */
    4487:   PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");
    4488:   VecGetSize(u,&N);
    4489:   for (i=0; i<N; i++) {
    4490:     VecCopy(u,uh);
    4491:     PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);
    4492:     for (j=-10; j<11; j++) {
    4493:       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
    4494:       VecSetValue(uh,i,value,ADD_VALUES);
    4495:       SNESComputeFunction(snes,uh,fh);
    4496:       VecNorm(fh,NORM_2,&norm);
    4497:       PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);
    4498:       value = -value;
    4499:       VecSetValue(uh,i,value,ADD_VALUES);
    4500:     }
    4501:   }
    4502:   VecDestroy(&uh);
    4503:   VecDestroy(&fh);
    4504:   return(0);
    4505: }

    4509: /*@
    4510:    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
    4511:    computing relative tolerance for linear solvers within an inexact
    4512:    Newton method.

    4514:    Logically Collective on SNES

    4516:    Input Parameters:
    4517: +  snes - SNES context
    4518: -  flag - PETSC_TRUE or PETSC_FALSE

    4520:     Options Database:
    4521: +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
    4522: .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
    4523: .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
    4524: .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
    4525: .  -snes_ksp_ew_gamma <gamma> - Sets gamma
    4526: .  -snes_ksp_ew_alpha <alpha> - Sets alpha
    4527: .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
    4528: -  -snes_ksp_ew_threshold <threshold> - Sets threshold

    4530:    Notes:
    4531:    Currently, the default is to use a constant relative tolerance for
    4532:    the inner linear solvers.  Alternatively, one can use the
    4533:    Eisenstat-Walker method, where the relative convergence tolerance
    4534:    is reset at each Newton iteration according progress of the nonlinear
    4535:    solver.

    4537:    Level: advanced

    4539:    Reference:
    4540:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
    4541:    inexact Newton method", SISC 17 (1), pp.16-32, 1996.

    4543: .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton

    4545: .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
    4546: @*/
    4547: PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
    4548: {
    4552:   snes->ksp_ewconv = flag;
    4553:   return(0);
    4554: }

    4558: /*@
    4559:    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
    4560:    for computing relative tolerance for linear solvers within an
    4561:    inexact Newton method.

    4563:    Not Collective

    4565:    Input Parameter:
    4566: .  snes - SNES context

    4568:    Output Parameter:
    4569: .  flag - PETSC_TRUE or PETSC_FALSE

    4571:    Notes:
    4572:    Currently, the default is to use a constant relative tolerance for
    4573:    the inner linear solvers.  Alternatively, one can use the
    4574:    Eisenstat-Walker method, where the relative convergence tolerance
    4575:    is reset at each Newton iteration according progress of the nonlinear
    4576:    solver.

    4578:    Level: advanced

    4580:    Reference:
    4581:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
    4582:    inexact Newton method", SISC 17 (1), pp.16-32, 1996.

    4584: .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton

    4586: .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
    4587: @*/
    4588: PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
    4589: {
    4593:   *flag = snes->ksp_ewconv;
    4594:   return(0);
    4595: }

    4599: /*@
    4600:    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
    4601:    convergence criteria for the linear solvers within an inexact
    4602:    Newton method.

    4604:    Logically Collective on SNES

    4606:    Input Parameters:
    4607: +    snes - SNES context
    4608: .    version - version 1, 2 (default is 2) or 3
    4609: .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
    4610: .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
    4611: .    gamma - multiplicative factor for version 2 rtol computation
    4612:              (0 <= gamma2 <= 1)
    4613: .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
    4614: .    alpha2 - power for safeguard
    4615: -    threshold - threshold for imposing safeguard (0 < threshold < 1)

    4617:    Note:
    4618:    Version 3 was contributed by Luis Chacon, June 2006.

    4620:    Use PETSC_DEFAULT to retain the default for any of the parameters.

    4622:    Level: advanced

    4624:    Reference:
    4625:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
    4626:    inexact Newton method", Utah State University Math. Stat. Dept. Res.
    4627:    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.

    4629: .keywords: SNES, KSP, Eisenstat, Walker, set, parameters

    4631: .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
    4632: @*/
    4633: PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
    4634: {
    4635:   SNESKSPEW *kctx;

    4639:   kctx = (SNESKSPEW*)snes->kspconvctx;
    4640:   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");

    4649:   if (version != PETSC_DEFAULT)   kctx->version   = version;
    4650:   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
    4651:   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
    4652:   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
    4653:   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
    4654:   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
    4655:   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;

    4657:   if (kctx->version < 1 || kctx->version > 3) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 and 3 are supported: %D",kctx->version);
    4658:   if (kctx->rtol_0 < 0.0 || kctx->rtol_0 >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_0 < 1.0: %g",(double)kctx->rtol_0);
    4659:   if (kctx->rtol_max < 0.0 || kctx->rtol_max >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_max (%g) < 1.0\n",(double)kctx->rtol_max);
    4660:   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%g) <= 1.0\n",(double)kctx->gamma);
    4661:   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%g) <= 2.0\n",(double)kctx->alpha);
    4662:   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%g) < 1.0\n",(double)kctx->threshold);
    4663:   return(0);
    4664: }

    4668: /*@
    4669:    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
    4670:    convergence criteria for the linear solvers within an inexact
    4671:    Newton method.

    4673:    Not Collective

    4675:    Input Parameters:
    4676:      snes - SNES context

    4678:    Output Parameters:
    4679: +    version - version 1, 2 (default is 2) or 3
    4680: .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
    4681: .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
    4682: .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
    4683: .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
    4684: .    alpha2 - power for safeguard
    4685: -    threshold - threshold for imposing safeguard (0 < threshold < 1)

    4687:    Level: advanced

    4689: .keywords: SNES, KSP, Eisenstat, Walker, get, parameters

    4691: .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
    4692: @*/
    4693: PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
    4694: {
    4695:   SNESKSPEW *kctx;

    4699:   kctx = (SNESKSPEW*)snes->kspconvctx;
    4700:   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
    4701:   if (version)   *version   = kctx->version;
    4702:   if (rtol_0)    *rtol_0    = kctx->rtol_0;
    4703:   if (rtol_max)  *rtol_max  = kctx->rtol_max;
    4704:   if (gamma)     *gamma     = kctx->gamma;
    4705:   if (alpha)     *alpha     = kctx->alpha;
    4706:   if (alpha2)    *alpha2    = kctx->alpha2;
    4707:   if (threshold) *threshold = kctx->threshold;
    4708:   return(0);
    4709: }

    4713:  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
    4714: {
    4716:   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
    4717:   PetscReal      rtol  = PETSC_DEFAULT,stol;

    4720:   if (!snes->ksp_ewconv) return(0);
    4721:   if (!snes->iter) {
    4722:     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
    4723:     VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);
    4724:   }
    4725:   else {
    4726:     if (kctx->version == 1) {
    4727:       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
    4728:       if (rtol < 0.0) rtol = -rtol;
    4729:       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
    4730:       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
    4731:     } else if (kctx->version == 2) {
    4732:       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
    4733:       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
    4734:       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
    4735:     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
    4736:       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
    4737:       /* safeguard: avoid sharp decrease of rtol */
    4738:       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
    4739:       stol = PetscMax(rtol,stol);
    4740:       rtol = PetscMin(kctx->rtol_0,stol);
    4741:       /* safeguard: avoid oversolving */
    4742:       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
    4743:       stol = PetscMax(rtol,stol);
    4744:       rtol = PetscMin(kctx->rtol_0,stol);
    4745:     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
    4746:   }
    4747:   /* safeguard: avoid rtol greater than one */
    4748:   rtol = PetscMin(rtol,kctx->rtol_max);
    4749:   KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);
    4750:   PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);
    4751:   return(0);
    4752: }

    4756: PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
    4757: {
    4759:   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
    4760:   PCSide         pcside;
    4761:   Vec            lres;

    4764:   if (!snes->ksp_ewconv) return(0);
    4765:   KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);
    4766:   kctx->norm_last = snes->norm;
    4767:   if (kctx->version == 1) {
    4768:     PC        pc;
    4769:     PetscBool isNone;

    4771:     KSPGetPC(ksp, &pc);
    4772:     PetscObjectTypeCompare((PetscObject) pc, PCNONE, &isNone);
    4773:     KSPGetPCSide(ksp,&pcside);
    4774:      if (pcside == PC_RIGHT || isNone) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
    4775:       /* KSP residual is true linear residual */
    4776:       KSPGetResidualNorm(ksp,&kctx->lresid_last);
    4777:     } else {
    4778:       /* KSP residual is preconditioned residual */
    4779:       /* compute true linear residual norm */
    4780:       VecDuplicate(b,&lres);
    4781:       MatMult(snes->jacobian,x,lres);
    4782:       VecAYPX(lres,-1.0,b);
    4783:       VecNorm(lres,NORM_2,&kctx->lresid_last);
    4784:       VecDestroy(&lres);
    4785:     }
    4786:   }
    4787:   return(0);
    4788: }

    4792: /*@
    4793:    SNESGetKSP - Returns the KSP context for a SNES solver.

    4795:    Not Collective, but if SNES object is parallel, then KSP object is parallel

    4797:    Input Parameter:
    4798: .  snes - the SNES context

    4800:    Output Parameter:
    4801: .  ksp - the KSP context

    4803:    Notes:
    4804:    The user can then directly manipulate the KSP context to set various
    4805:    options, etc.  Likewise, the user can then extract and manipulate the
    4806:    PC contexts as well.

    4808:    Level: beginner

    4810: .keywords: SNES, nonlinear, get, KSP, context

    4812: .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
    4813: @*/
    4814: PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
    4815: {

    4822:   if (!snes->ksp) {
    4823:     PetscBool monitor = PETSC_FALSE;

    4825:     KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);
    4826:     PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);
    4827:     PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);

    4829:     KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);
    4830:     KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);

    4832:     PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes",&monitor,NULL);
    4833:     if (monitor) {
    4834:       KSPMonitorSet(snes->ksp,KSPMonitorSNES,snes,NULL);
    4835:     }
    4836:     monitor = PETSC_FALSE;
    4837:     PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes_lg",&monitor,NULL);
    4838:     if (monitor) {
    4839:       PetscObject *objs;
    4840:       KSPMonitorSNESLGResidualNormCreate(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,600,600,&objs);
    4841:       objs[0] = (PetscObject) snes;
    4842:       KSPMonitorSet(snes->ksp,(PetscErrorCode (*)(KSP,PetscInt,PetscReal,void*))KSPMonitorSNESLGResidualNorm,objs,(PetscErrorCode (*)(void**))KSPMonitorSNESLGResidualNormDestroy);
    4843:     }
    4844:   }
    4845:   *ksp = snes->ksp;
    4846:   return(0);
    4847: }

    4850: #include <petsc/private/dmimpl.h>
    4853: /*@
    4854:    SNESSetDM - Sets the DM that may be used by some preconditioners

    4856:    Logically Collective on SNES

    4858:    Input Parameters:
    4859: +  snes - the preconditioner context
    4860: -  dm - the dm

    4862:    Level: intermediate

    4864: .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
    4865: @*/
    4866: PetscErrorCode  SNESSetDM(SNES snes,DM dm)
    4867: {
    4869:   KSP            ksp;
    4870:   DMSNES         sdm;

    4874:   if (dm) {PetscObjectReference((PetscObject)dm);}
    4875:   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
    4876:     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
    4877:       DMCopyDMSNES(snes->dm,dm);
    4878:       DMGetDMSNES(snes->dm,&sdm);
    4879:       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
    4880:     }
    4881:     DMDestroy(&snes->dm);
    4882:   }
    4883:   snes->dm     = dm;
    4884:   snes->dmAuto = PETSC_FALSE;

    4886:   SNESGetKSP(snes,&ksp);
    4887:   KSPSetDM(ksp,dm);
    4888:   KSPSetDMActive(ksp,PETSC_FALSE);
    4889:   if (snes->pc) {
    4890:     SNESSetDM(snes->pc, snes->dm);
    4891:     SNESSetNPCSide(snes,snes->pcside);
    4892:   }
    4893:   return(0);
    4894: }

    4898: /*@
    4899:    SNESGetDM - Gets the DM that may be used by some preconditioners

    4901:    Not Collective but DM obtained is parallel on SNES

    4903:    Input Parameter:
    4904: . snes - the preconditioner context

    4906:    Output Parameter:
    4907: .  dm - the dm

    4909:    Level: intermediate

    4911: .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
    4912: @*/
    4913: PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
    4914: {

    4919:   if (!snes->dm) {
    4920:     DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);
    4921:     snes->dmAuto = PETSC_TRUE;
    4922:   }
    4923:   *dm = snes->dm;
    4924:   return(0);
    4925: }

    4929: /*@
    4930:   SNESSetNPC - Sets the nonlinear preconditioner to be used.

    4932:   Collective on SNES

    4934:   Input Parameters:
    4935: + snes - iterative context obtained from SNESCreate()
    4936: - pc   - the preconditioner object

    4938:   Notes:
    4939:   Use SNESGetNPC() to retrieve the preconditioner context (for example,
    4940:   to configure it using the API).

    4942:   Level: developer

    4944: .keywords: SNES, set, precondition
    4945: .seealso: SNESGetNPC(), SNESHasNPC()
    4946: @*/
    4947: PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
    4948: {

    4955:   PetscObjectReference((PetscObject) pc);
    4956:   SNESDestroy(&snes->pc);
    4957:   snes->pc = pc;
    4958:   PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->pc);
    4959:   return(0);
    4960: }

    4964: /*@
    4965:   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.

    4967:   Not Collective

    4969:   Input Parameter:
    4970: . snes - iterative context obtained from SNESCreate()

    4972:   Output Parameter:
    4973: . pc - preconditioner context

    4975:   Notes: If a SNES was previously set with SNESSetNPC() then that SNES is returned.

    4977:   Level: developer

    4979: .keywords: SNES, get, preconditioner
    4980: .seealso: SNESSetNPC(), SNESHasNPC()
    4981: @*/
    4982: PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
    4983: {
    4985:   const char     *optionsprefix;

    4990:   if (!snes->pc) {
    4991:     SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);
    4992:     PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);
    4993:     PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->pc);
    4994:     SNESGetOptionsPrefix(snes,&optionsprefix);
    4995:     SNESSetOptionsPrefix(snes->pc,optionsprefix);
    4996:     SNESAppendOptionsPrefix(snes->pc,"npc_");
    4997:     SNESSetCountersReset(snes->pc,PETSC_FALSE);
    4998:   }
    4999:   *pc = snes->pc;
    5000:   return(0);
    5001: }

    5005: /*@
    5006:   SNESHasNPC - Returns whether a nonlinear preconditioner exists

    5008:   Not Collective

    5010:   Input Parameter:
    5011: . snes - iterative context obtained from SNESCreate()

    5013:   Output Parameter:
    5014: . has_npc - whether the SNES has an NPC or not

    5016:   Level: developer

    5018: .keywords: SNES, has, preconditioner
    5019: .seealso: SNESSetNPC(), SNESGetNPC()
    5020: @*/
    5021: PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
    5022: {
    5025:   *has_npc = (PetscBool) (snes->pc ? PETSC_TRUE : PETSC_FALSE);
    5026:   return(0);
    5027: }

    5031: /*@
    5032:     SNESSetNPCSide - Sets the preconditioning side.

    5034:     Logically Collective on SNES

    5036:     Input Parameter:
    5037: .   snes - iterative context obtained from SNESCreate()

    5039:     Output Parameter:
    5040: .   side - the preconditioning side, where side is one of
    5041: .vb
    5042:       PC_LEFT - left preconditioning (default)
    5043:       PC_RIGHT - right preconditioning
    5044: .ve

    5046:     Options Database Keys:
    5047: .   -snes_pc_side <right,left>

    5049:     Level: intermediate

    5051: .keywords: SNES, set, right, left, side, preconditioner, flag

    5053: .seealso: SNESGetNPCSide(), KSPSetPCSide()
    5054: @*/
    5055: PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
    5056: {
    5060:   snes->pcside = side;
    5061:   return(0);
    5062: }

    5066: /*@
    5067:     SNESGetNPCSide - Gets the preconditioning side.

    5069:     Not Collective

    5071:     Input Parameter:
    5072: .   snes - iterative context obtained from SNESCreate()

    5074:     Output Parameter:
    5075: .   side - the preconditioning side, where side is one of
    5076: .vb
    5077:       PC_LEFT - left preconditioning (default)
    5078:       PC_RIGHT - right preconditioning
    5079: .ve

    5081:     Level: intermediate

    5083: .keywords: SNES, get, right, left, side, preconditioner, flag

    5085: .seealso: SNESSetNPCSide(), KSPGetPCSide()
    5086: @*/
    5087: PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
    5088: {
    5092:   *side = snes->pcside;
    5093:   return(0);
    5094: }

    5098: /*@
    5099:   SNESSetLineSearch - Sets the linesearch on the SNES instance.

    5101:   Collective on SNES

    5103:   Input Parameters:
    5104: + snes - iterative context obtained from SNESCreate()
    5105: - linesearch   - the linesearch object

    5107:   Notes:
    5108:   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
    5109:   to configure it using the API).

    5111:   Level: developer

    5113: .keywords: SNES, set, linesearch
    5114: .seealso: SNESGetLineSearch()
    5115: @*/
    5116: PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
    5117: {

    5124:   PetscObjectReference((PetscObject) linesearch);
    5125:   SNESLineSearchDestroy(&snes->linesearch);

    5127:   snes->linesearch = linesearch;

    5129:   PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);
    5130:   return(0);
    5131: }

    5135: /*@
    5136:   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
    5137:   or creates a default line search instance associated with the SNES and returns it.

    5139:   Not Collective

    5141:   Input Parameter:
    5142: . snes - iterative context obtained from SNESCreate()

    5144:   Output Parameter:
    5145: . linesearch - linesearch context

    5147:   Level: beginner

    5149: .keywords: SNES, get, linesearch
    5150: .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
    5151: @*/
    5152: PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
    5153: {
    5155:   const char     *optionsprefix;

    5160:   if (!snes->linesearch) {
    5161:     SNESGetOptionsPrefix(snes, &optionsprefix);
    5162:     SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);
    5163:     SNESLineSearchSetSNES(snes->linesearch, snes);
    5164:     SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);
    5165:     PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);
    5166:     PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);
    5167:   }
    5168:   *linesearch = snes->linesearch;
    5169:   return(0);
    5170: }

    5172: #if defined(PETSC_HAVE_MATLAB_ENGINE)
    5173: #include <mex.h>

    5175: typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;

    5179: /*
    5180:    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().

    5182:    Collective on SNES

    5184:    Input Parameters:
    5185: +  snes - the SNES context
    5186: -  x - input vector

    5188:    Output Parameter:
    5189: .  y - function vector, as set by SNESSetFunction()

    5191:    Notes:
    5192:    SNESComputeFunction() is typically used within nonlinear solvers
    5193:    implementations, so most users would not generally call this routine
    5194:    themselves.

    5196:    Level: developer

    5198: .keywords: SNES, nonlinear, compute, function

    5200: .seealso: SNESSetFunction(), SNESGetFunction()
    5201: */
    5202: PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
    5203: {
    5204:   PetscErrorCode    ierr;
    5205:   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
    5206:   int               nlhs  = 1,nrhs = 5;
    5207:   mxArray           *plhs[1],*prhs[5];
    5208:   long long int     lx = 0,ly = 0,ls = 0;

    5217:   /* call Matlab function in ctx with arguments x and y */

    5219:   PetscMemcpy(&ls,&snes,sizeof(snes));
    5220:   PetscMemcpy(&lx,&x,sizeof(x));
    5221:   PetscMemcpy(&ly,&y,sizeof(x));
    5222:   prhs[0] = mxCreateDoubleScalar((double)ls);
    5223:   prhs[1] = mxCreateDoubleScalar((double)lx);
    5224:   prhs[2] = mxCreateDoubleScalar((double)ly);
    5225:   prhs[3] = mxCreateString(sctx->funcname);
    5226:   prhs[4] = sctx->ctx;
    5227:   mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");
    5228:   mxGetScalar(plhs[0]);
    5229:   mxDestroyArray(prhs[0]);
    5230:   mxDestroyArray(prhs[1]);
    5231:   mxDestroyArray(prhs[2]);
    5232:   mxDestroyArray(prhs[3]);
    5233:   mxDestroyArray(plhs[0]);
    5234:   return(0);
    5235: }

    5239: /*
    5240:    SNESSetFunctionMatlab - Sets the function evaluation routine and function
    5241:    vector for use by the SNES routines in solving systems of nonlinear
    5242:    equations from MATLAB. Here the function is a string containing the name of a MATLAB function

    5244:    Logically Collective on SNES

    5246:    Input Parameters:
    5247: +  snes - the SNES context
    5248: .  r - vector to store function value
    5249: -  f - function evaluation routine

    5251:    Notes:
    5252:    The Newton-like methods typically solve linear systems of the form
    5253: $      f'(x) x = -f(x),
    5254:    where f'(x) denotes the Jacobian matrix and f(x) is the function.

    5256:    Level: beginner

    5258:    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;

    5260: .keywords: SNES, nonlinear, set, function

    5262: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
    5263: */
    5264: PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *f,mxArray *ctx)
    5265: {
    5266:   PetscErrorCode    ierr;
    5267:   SNESMatlabContext *sctx;

    5270:   /* currently sctx is memory bleed */
    5271:   PetscNew(&sctx);
    5272:   PetscStrallocpy(f,&sctx->funcname);
    5273:   /*
    5274:      This should work, but it doesn't
    5275:   sctx->ctx = ctx;
    5276:   mexMakeArrayPersistent(sctx->ctx);
    5277:   */
    5278:   sctx->ctx = mxDuplicateArray(ctx);
    5279:   SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);
    5280:   return(0);
    5281: }

    5285: /*
    5286:    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().

    5288:    Collective on SNES

    5290:    Input Parameters:
    5291: +  snes - the SNES context
    5292: .  x - input vector
    5293: .  A, B - the matrices
    5294: -  ctx - user context

    5296:    Level: developer

    5298: .keywords: SNES, nonlinear, compute, function

    5300: .seealso: SNESSetFunction(), SNESGetFunction()
    5301: @*/
    5302: PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat A,Mat B,void *ctx)
    5303: {
    5304:   PetscErrorCode    ierr;
    5305:   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
    5306:   int               nlhs  = 2,nrhs = 6;
    5307:   mxArray           *plhs[2],*prhs[6];
    5308:   long long int     lx = 0,lA = 0,ls = 0, lB = 0;

    5314:   /* call Matlab function in ctx with arguments x and y */

    5316:   PetscMemcpy(&ls,&snes,sizeof(snes));
    5317:   PetscMemcpy(&lx,&x,sizeof(x));
    5318:   PetscMemcpy(&lA,A,sizeof(x));
    5319:   PetscMemcpy(&lB,B,sizeof(x));
    5320:   prhs[0] = mxCreateDoubleScalar((double)ls);
    5321:   prhs[1] = mxCreateDoubleScalar((double)lx);
    5322:   prhs[2] = mxCreateDoubleScalar((double)lA);
    5323:   prhs[3] = mxCreateDoubleScalar((double)lB);
    5324:   prhs[4] = mxCreateString(sctx->funcname);
    5325:   prhs[5] = sctx->ctx;
    5326:   mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");
    5327:   mxGetScalar(plhs[0]);
    5328:   mxDestroyArray(prhs[0]);
    5329:   mxDestroyArray(prhs[1]);
    5330:   mxDestroyArray(prhs[2]);
    5331:   mxDestroyArray(prhs[3]);
    5332:   mxDestroyArray(prhs[4]);
    5333:   mxDestroyArray(plhs[0]);
    5334:   mxDestroyArray(plhs[1]);
    5335:   return(0);
    5336: }

    5340: /*
    5341:    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
    5342:    vector for use by the SNES routines in solving systems of nonlinear
    5343:    equations from MATLAB. Here the function is a string containing the name of a MATLAB function

    5345:    Logically Collective on SNES

    5347:    Input Parameters:
    5348: +  snes - the SNES context
    5349: .  A,B - Jacobian matrices
    5350: .  J - function evaluation routine
    5351: -  ctx - user context

    5353:    Level: developer

    5355:    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;

    5357: .keywords: SNES, nonlinear, set, function

    5359: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), J
    5360: */
    5361: PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *J,mxArray *ctx)
    5362: {
    5363:   PetscErrorCode    ierr;
    5364:   SNESMatlabContext *sctx;

    5367:   /* currently sctx is memory bleed */
    5368:   PetscNew(&sctx);
    5369:   PetscStrallocpy(J,&sctx->funcname);
    5370:   /*
    5371:      This should work, but it doesn't
    5372:   sctx->ctx = ctx;
    5373:   mexMakeArrayPersistent(sctx->ctx);
    5374:   */
    5375:   sctx->ctx = mxDuplicateArray(ctx);
    5376:   SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);
    5377:   return(0);
    5378: }

    5382: /*
    5383:    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().

    5385:    Collective on SNES

    5387: .seealso: SNESSetFunction(), SNESGetFunction()
    5388: @*/
    5389: PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
    5390: {
    5391:   PetscErrorCode    ierr;
    5392:   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
    5393:   int               nlhs  = 1,nrhs = 6;
    5394:   mxArray           *plhs[1],*prhs[6];
    5395:   long long int     lx = 0,ls = 0;
    5396:   Vec               x  = snes->vec_sol;

    5401:   PetscMemcpy(&ls,&snes,sizeof(snes));
    5402:   PetscMemcpy(&lx,&x,sizeof(x));
    5403:   prhs[0] = mxCreateDoubleScalar((double)ls);
    5404:   prhs[1] = mxCreateDoubleScalar((double)it);
    5405:   prhs[2] = mxCreateDoubleScalar((double)fnorm);
    5406:   prhs[3] = mxCreateDoubleScalar((double)lx);
    5407:   prhs[4] = mxCreateString(sctx->funcname);
    5408:   prhs[5] = sctx->ctx;
    5409:   mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");
    5410:   mxGetScalar(plhs[0]);
    5411:   mxDestroyArray(prhs[0]);
    5412:   mxDestroyArray(prhs[1]);
    5413:   mxDestroyArray(prhs[2]);
    5414:   mxDestroyArray(prhs[3]);
    5415:   mxDestroyArray(prhs[4]);
    5416:   mxDestroyArray(plhs[0]);
    5417:   return(0);
    5418: }

    5422: /*
    5423:    SNESMonitorSetMatlab - Sets the monitor function from MATLAB

    5425:    Level: developer

    5427:    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;

    5429: .keywords: SNES, nonlinear, set, function

    5431: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
    5432: */
    5433: PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *f,mxArray *ctx)
    5434: {
    5435:   PetscErrorCode    ierr;
    5436:   SNESMatlabContext *sctx;

    5439:   /* currently sctx is memory bleed */
    5440:   PetscNew(&sctx);
    5441:   PetscStrallocpy(f,&sctx->funcname);
    5442:   /*
    5443:      This should work, but it doesn't
    5444:   sctx->ctx = ctx;
    5445:   mexMakeArrayPersistent(sctx->ctx);
    5446:   */
    5447:   sctx->ctx = mxDuplicateArray(ctx);
    5448:   SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);
    5449:   return(0);
    5450: }

    5452: #endif