Date: 2015-10-02T22:23:17+00:00

Actual source code: snes.c
petsc-3.6.2 2015-10-02
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      2: #include <petsc/private/snesimpl.h>      /*I "petscsnes.h"  I*/
      3: #include <petscdmshell.h>

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

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

     14: /*@
     15:    SNESSetErrorIfNotConverged - Causes SNESSolve() to generate an error if the solver has not converged.

     17:    Logically Collective on SNES

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

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

     26:    Level: intermediate

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

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

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

     47: /*@
     48:    SNESGetErrorIfNotConverged - Will SNESSolve() generate an error if the solver does not converge?

     50:    Not Collective

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

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

     58:    Level: intermediate

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

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

     75: /*@
     76:    SNESSetFunctionDomainError - tells SNES that the input vector to your SNESFunction is not
     77:      in the functions domain. For example, negative pressure.

     79:    Logically Collective on SNES

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

     84:    Level: advanced

     86: .keywords: SNES, view

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

    101: /*@
    102:    SNESGetFunctionDomainError - Gets the status of the domain error after a call to SNESComputeFunction;

    104:    Logically Collective on SNES

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

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

    112:    Level: advanced

    114: .keywords: SNES, view

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

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

    132:   Collective on PetscViewer

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

    139:    Level: intermediate

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

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

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

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

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

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

    195:    Collective on SNES

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

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

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

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

    215:    Level: beginner

    217: .keywords: SNES, view

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

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

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

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

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

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

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

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

    372: /*
    373:   We retain a list of functions that also take SNES command
    374:   line options. These are called at the end SNESSetFromOptions()
    375: */
    376: #define MAXSETFROMOPTIONS 5
    377: static PetscInt numberofsetfromoptions;
    378: static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);

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

    385:   Not Collective

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

    390:   Level: developer

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    560: /*@
    561:    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()

    563:    Collective

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

    568:    Level: developer

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

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

    619: /*@
    620:    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.

    622:    Collective on SNES

    624:    Input Parameter:
    625: .  snes - the SNES context

    627:    Options Database Keys:
    628: +  -snes_type <type> - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, SNESType for complete list
    629: .  -snes_stol - convergence tolerance in terms of the norm
    630:                 of the change in the solution between steps
    631: .  -snes_atol <abstol> - absolute tolerance of residual norm
    632: .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
    633: .  -snes_max_it <max_it> - maximum number of iterations
    634: .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
    635: .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
    636: .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
    637: .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
    638: .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
    639: .  -snes_trtol <trtol> - trust region tolerance
    640: .  -snes_no_convergence_test - skip convergence test in nonlinear
    641:                                solver; hence iterations will continue until max_it
    642:                                or some other criterion is reached. Saves expense
    643:                                of convergence test
    644: .  -snes_monitor <optional filename> - prints residual norm at each iteration. if no
    645:                                        filename given prints to stdout
    646: .  -snes_monitor_solution - plots solution at each iteration
    647: .  -snes_monitor_residual - plots residual (not its norm) at each iteration
    648: .  -snes_monitor_solution_update - plots update to solution at each iteration
    649: .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
    650: .  -snes_monitor_lg_range - plots residual norm at each iteration
    651: .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
    652: .  -snes_fd_color - use finite differences with coloring to compute Jacobian
    653: .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
    654: -  -snes_converged_reason - print the reason for convergence/divergence after each solve

    656:     Options Database for Eisenstat-Walker method:
    657: +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
    658: .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
    659: .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
    660: .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
    661: .  -snes_ksp_ew_gamma <gamma> - Sets gamma
    662: .  -snes_ksp_ew_alpha <alpha> - Sets alpha
    663: .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
    664: -  -snes_ksp_ew_threshold <threshold> - Sets threshold

    666:    Notes:
    667:    To see all options, run your program with the -help option or consult
    668:    Users-Manual: ch_snes

    670:    Level: beginner

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

    674: .seealso: SNESSetOptionsPrefix()
    675: @*/
    676: PetscErrorCode  SNESSetFromOptions(SNES snes)
    677: {
    678:   PetscBool      flg,pcset,persist,set;
    679:   PetscInt       i,indx,lag,grids;
    680:   const char     *deft        = SNESNEWTONLS;
    681:   const char     *convtests[] = {"default","skip"};
    682:   SNESKSPEW      *kctx        = NULL;
    683:   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
    684:   PetscViewer    monviewer;
    686:   PCSide         pcside;
    687:   const char     *optionsprefix;

    691:   SNESRegisterAll();
    692:   PetscObjectOptionsBegin((PetscObject)snes);
    693:   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
    694:   PetscOptionsFList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);
    695:   if (flg) {
    696:     SNESSetType(snes,type);
    697:   } else if (!((PetscObject)snes)->type_name) {
    698:     SNESSetType(snes,deft);
    699:   }
    700:   PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,NULL);
    701:   PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,NULL);

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

    710:   PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);
    711:   if (flg) {
    712:     SNESSetLagPreconditioner(snes,lag);
    713:   }
    714:   PetscOptionsBool("-snes_lag_preconditioner_persists","Preconditioner lagging through multiple solves","SNESSetLagPreconditionerPersists",snes->lagjac_persist,&persist,&flg);
    715:   if (flg) {
    716:     SNESSetLagPreconditionerPersists(snes,persist);
    717:   }
    718:   PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);
    719:   if (flg) {
    720:     SNESSetLagJacobian(snes,lag);
    721:   }
    722:   PetscOptionsBool("-snes_lag_jacobian_persists","Jacobian lagging through multiple solves","SNESSetLagJacobianPersists",snes->lagjac_persist,&persist,&flg);
    723:   if (flg) {
    724:     SNESSetLagJacobianPersists(snes,persist);
    725:   }

    727:   PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);
    728:   if (flg) {
    729:     SNESSetGridSequence(snes,grids);
    730:   }

    732:   PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);
    733:   if (flg) {
    734:     switch (indx) {
    735:     case 0: SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL); break;
    736:     case 1: SNESSetConvergenceTest(snes,SNESConvergedSkip,NULL,NULL);    break;
    737:     }
    738:   }

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

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

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

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

    750:   PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,NULL);
    751:   PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,NULL);
    752:   PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,NULL);
    753:   PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,NULL);
    754:   PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,NULL);
    755:   PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,NULL);
    756:   PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,NULL);

    758:   flg  = PETSC_FALSE;
    759:   PetscOptionsBool("-snes_check_jacobian","Check each Jacobian with a differenced one","SNESUpdateCheckJacobian",flg,&flg,&set);
    760:   if (set && flg) {
    761:     SNESSetUpdate(snes,SNESUpdateCheckJacobian);
    762:   }

    764:   flg  = PETSC_FALSE;
    765:   PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,&set);
    766:   if (set && flg) {SNESMonitorCancel(snes);}

    768:   PetscOptionsString("-snes_monitor","Monitor norm of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);
    769:   if (flg) {
    770:     PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);
    771:     SNESMonitorSet(snes,SNESMonitorDefault,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);
    772:   }

    774:   PetscOptionsString("-snes_monitor_range","Monitor range of elements of function","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);
    775:   if (flg) {
    776:     SNESMonitorSet(snes,SNESMonitorRange,0,0);
    777:   }

    779:   PetscOptionsString("-snes_ratiomonitor","Monitor ratios of norms of function","SNESMonitorSetRatio","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);
    780:   if (flg) {
    781:     PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);
    782:     SNESMonitorSetRatio(snes,monviewer);
    783:   }

    785:   PetscOptionsString("-snes_monitor_short","Monitor norm of function (fewer digits)","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);
    786:   if (flg) {
    787:     PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);
    788:     SNESMonitorSet(snes,SNESMonitorDefaultShort,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);
    789:   }

    791:   PetscOptionsString("-snes_monitor_field","Monitor norm of function (split into fields)","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);
    792:   if (flg) {
    793:     PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);
    794:     SNESMonitorSet(snes,SNESMonitorDefaultField,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);
    795:   }

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

    800:   flg  = PETSC_FALSE;
    801:   PetscOptionsBool("-snes_monitor_solution","Plot solution at each iteration","SNESMonitorSolution",flg,&flg,NULL);
    802:   if (flg) {SNESMonitorSet(snes,SNESMonitorSolution,0,0);}
    803:   flg  = PETSC_FALSE;
    804:   PetscOptionsBool("-snes_monitor_solution_update","Plot correction at each iteration","SNESMonitorSolutionUpdate",flg,&flg,NULL);
    805:   if (flg) {SNESMonitorSet(snes,SNESMonitorSolutionUpdate,0,0);}
    806:   flg  = PETSC_FALSE;
    807:   PetscOptionsBool("-snes_monitor_residual","Plot residual at each iteration","SNESMonitorResidual",flg,&flg,NULL);
    808:   if (flg) {SNESMonitorSet(snes,SNESMonitorResidual,0,0);}
    809:   flg  = PETSC_FALSE;
    810:   PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);
    811:   if (flg) {
    812:     PetscObject *objs;

    814:     SNESMonitorLGCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&objs);
    815:     SNESMonitorSet(snes,(PetscErrorCode (*)(SNES,PetscInt,PetscReal,void*))SNESMonitorLGResidualNorm,objs,(PetscErrorCode (*)(void**))SNESMonitorLGDestroy);
    816:   }
    817:   flg  = PETSC_FALSE;
    818:   PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);
    819:   if (flg) {
    820:     PetscViewer ctx;

    822:     PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,&ctx);
    823:     SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);
    824:   }

    826:   flg  = PETSC_FALSE;
    827:   PetscOptionsBool("-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",flg,&flg,NULL);
    828:   if (flg) {SNESMonitorSet(snes,SNESMonitorJacUpdateSpectrum,0,0);}

    831:   PetscOptionsString("-snes_monitor_fields","Monitor norm of function per field","SNESMonitorSet","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);
    832:   if (flg) {
    833:     PetscViewerASCIIOpen(PetscObjectComm((PetscObject)snes),monfilename,&monviewer);
    834:     SNESMonitorSet(snes,SNESMonitorFields,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);
    835:   }

    837:   flg  = PETSC_FALSE;
    838:   PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);
    839:   if (flg) {
    840:     void *functx;
    841:     SNESGetFunction(snes,NULL,NULL,&functx);
    842:     SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);
    843:     PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");
    844:   }

    846:   flg  = PETSC_FALSE;
    847:   PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);
    848:   if (flg) {
    849:     SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);
    850:   }

    852:   flg  = PETSC_FALSE;
    853:   PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);
    854:   if (flg) {
    855:     DM             dm;
    856:     DMSNES         sdm;
    857:     SNESGetDM(snes,&dm);
    858:     DMGetDMSNES(dm,&sdm);
    859:     sdm->jacobianctx = NULL;
    860:     SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,0);
    861:     PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");
    862:   }

    864:   flg  = PETSC_FALSE;
    865:   PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf_operator,&flg);
    866:   if (flg && snes->mf_operator) {
    867:     snes->mf_operator = PETSC_TRUE;
    868:     snes->mf          = PETSC_TRUE;
    869:   }
    870:   flg  = PETSC_FALSE;
    871:   PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","MatCreateSNESMF",PETSC_FALSE,&snes->mf,&flg);
    872:   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
    873:   PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,0);

    875:   flg  = PETSC_FALSE;
    876:   SNESGetNPCSide(snes,&pcside);
    877:   PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetNPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);
    878:   if (flg) {SNESSetNPCSide(snes,pcside);}

    880: #if defined(PETSC_HAVE_SAWS)
    881:   /*
    882:     Publish convergence information using SAWs
    883:   */
    884:   flg  = PETSC_FALSE;
    885:   PetscOptionsBool("-snes_monitor_saws","Publish SNES progress using SAWs","SNESMonitorSet",flg,&flg,NULL);
    886:   if (flg) {
    887:     void *ctx;
    888:     SNESMonitorSAWsCreate(snes,&ctx);
    889:     SNESMonitorSet(snes,SNESMonitorSAWs,ctx,SNESMonitorSAWsDestroy);
    890:   }
    891: #endif
    892: #if defined(PETSC_HAVE_SAWS)
    893:   {
    894:   PetscBool set;
    895:   flg  = PETSC_FALSE;
    896:   PetscOptionsBool("-snes_saws_block","Block for SAWs at end of SNESSolve","PetscObjectSAWsBlock",((PetscObject)snes)->amspublishblock,&flg,&set);
    897:   if (set) {
    898:     PetscObjectSAWsSetBlock((PetscObject)snes,flg);
    899:   }
    900:   }
    901: #endif

    903:   for (i = 0; i < numberofsetfromoptions; i++) {
    904:     (*othersetfromoptions[i])(snes);
    905:   }

    907:   if (snes->ops->setfromoptions) {
    908:     (*snes->ops->setfromoptions)(PetscOptionsObject,snes);
    909:   }

    911:   /* process any options handlers added with PetscObjectAddOptionsHandler() */
    912:   PetscObjectProcessOptionsHandlers((PetscObject)snes);
    913:   PetscOptionsEnd();

    915:   if (!snes->linesearch) {
    916:     SNESGetLineSearch(snes, &snes->linesearch);
    917:   }
    918:   SNESLineSearchSetFromOptions(snes->linesearch);

    920:   if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
    921:   KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);
    922:   KSPSetFromOptions(snes->ksp);

    924:   /* if someone has set the SNES NPC type, create it. */
    925:   SNESGetOptionsPrefix(snes, &optionsprefix);
    926:   PetscOptionsHasName(optionsprefix, "-npc_snes_type", &pcset);
    927:   if (pcset && (!snes->pc)) {
    928:     SNESGetNPC(snes, &snes->pc);
    929:   }
    930:   return(0);
    931: }

    935: /*@C
    936:    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
    937:    the nonlinear solvers.

    939:    Logically Collective on SNES

    941:    Input Parameters:
    942: +  snes - the SNES context
    943: .  compute - function to compute the context
    944: -  destroy - function to destroy the context

    946:    Level: intermediate

    948:    Notes:
    949:    This function is currently not available from Fortran.

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

    953: .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
    954: @*/
    955: PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
    956: {
    959:   snes->ops->usercompute = compute;
    960:   snes->ops->userdestroy = destroy;
    961:   return(0);
    962: }

    966: /*@
    967:    SNESSetApplicationContext - Sets the optional user-defined context for
    968:    the nonlinear solvers.

    970:    Logically Collective on SNES

    972:    Input Parameters:
    973: +  snes - the SNES context
    974: -  usrP - optional user context

    976:    Level: intermediate

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

    980: .seealso: SNESGetApplicationContext()
    981: @*/
    982: PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
    983: {
    985:   KSP            ksp;

    989:   SNESGetKSP(snes,&ksp);
    990:   KSPSetApplicationContext(ksp,usrP);
    991:   snes->user = usrP;
    992:   return(0);
    993: }

    997: /*@
    998:    SNESGetApplicationContext - Gets the user-defined context for the
    999:    nonlinear solvers.

    1001:    Not Collective

    1003:    Input Parameter:
    1004: .  snes - SNES context

    1006:    Output Parameter:
    1007: .  usrP - user context

    1009:    Level: intermediate

    1011: .keywords: SNES, nonlinear, get, application, context

    1013: .seealso: SNESSetApplicationContext()
    1014: @*/
    1015: PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
    1016: {
    1019:   *(void**)usrP = snes->user;
    1020:   return(0);
    1021: }

    1025: /*@
    1026:    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
    1027:    at this time.

    1029:    Not Collective

    1031:    Input Parameter:
    1032: .  snes - SNES context

    1034:    Output Parameter:
    1035: .  iter - iteration number

    1037:    Notes:
    1038:    For example, during the computation of iteration 2 this would return 1.

    1040:    This is useful for using lagged Jacobians (where one does not recompute the
    1041:    Jacobian at each SNES iteration). For example, the code
    1042: .vb
    1043:       SNESGetIterationNumber(snes,&it);
    1044:       if (!(it % 2)) {
    1045:         [compute Jacobian here]
    1046:       }
    1047: .ve
    1048:    can be used in your ComputeJacobian() function to cause the Jacobian to be
    1049:    recomputed every second SNES iteration.

    1051:    Level: intermediate

    1053: .keywords: SNES, nonlinear, get, iteration, number,

    1055: .seealso:   SNESGetLinearSolveIterations()
    1056: @*/
    1057: PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
    1058: {
    1062:   *iter = snes->iter;
    1063:   return(0);
    1064: }

    1068: /*@
    1069:    SNESSetIterationNumber - Sets the current iteration number.

    1071:    Not Collective

    1073:    Input Parameter:
    1074: .  snes - SNES context
    1075: .  iter - iteration number

    1077:    Level: developer

    1079: .keywords: SNES, nonlinear, set, iteration, number,

    1081: .seealso:   SNESGetLinearSolveIterations()
    1082: @*/
    1083: PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
    1084: {

    1089:   PetscObjectSAWsTakeAccess((PetscObject)snes);
    1090:   snes->iter = iter;
    1091:   PetscObjectSAWsGrantAccess((PetscObject)snes);
    1092:   return(0);
    1093: }

    1097: /*@
    1098:    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
    1099:    attempted by the nonlinear solver.

    1101:    Not Collective

    1103:    Input Parameter:
    1104: .  snes - SNES context

    1106:    Output Parameter:
    1107: .  nfails - number of unsuccessful steps attempted

    1109:    Notes:
    1110:    This counter is reset to zero for each successive call to SNESSolve().

    1112:    Level: intermediate

    1114: .keywords: SNES, nonlinear, get, number, unsuccessful, steps

    1116: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
    1117:           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
    1118: @*/
    1119: PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
    1120: {
    1124:   *nfails = snes->numFailures;
    1125:   return(0);
    1126: }

    1130: /*@
    1131:    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
    1132:    attempted by the nonlinear solver before it gives up.

    1134:    Not Collective

    1136:    Input Parameters:
    1137: +  snes     - SNES context
    1138: -  maxFails - maximum of unsuccessful steps

    1140:    Level: intermediate

    1142: .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps

    1144: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
    1145:           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
    1146: @*/
    1147: PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
    1148: {
    1151:   snes->maxFailures = maxFails;
    1152:   return(0);
    1153: }

    1157: /*@
    1158:    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
    1159:    attempted by the nonlinear solver before it gives up.

    1161:    Not Collective

    1163:    Input Parameter:
    1164: .  snes     - SNES context

    1166:    Output Parameter:
    1167: .  maxFails - maximum of unsuccessful steps

    1169:    Level: intermediate

    1171: .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps

    1173: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
    1174:           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()

    1176: @*/
    1177: PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
    1178: {
    1182:   *maxFails = snes->maxFailures;
    1183:   return(0);
    1184: }

    1188: /*@
    1189:    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
    1190:      done by SNES.

    1192:    Not Collective

    1194:    Input Parameter:
    1195: .  snes     - SNES context

    1197:    Output Parameter:
    1198: .  nfuncs - number of evaluations

    1200:    Level: intermediate

    1202:    Notes: Reset every time SNESSolve is called unless SNESSetCountersReset() is used.

    1204: .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps

    1206: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
    1207: @*/
    1208: PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
    1209: {
    1213:   *nfuncs = snes->nfuncs;
    1214:   return(0);
    1215: }

    1219: /*@
    1220:    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
    1221:    linear solvers.

    1223:    Not Collective

    1225:    Input Parameter:
    1226: .  snes - SNES context

    1228:    Output Parameter:
    1229: .  nfails - number of failed solves

    1231:    Level: intermediate

    1233:    Options Database Keys:
    1234: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

    1236:    Notes:
    1237:    This counter is reset to zero for each successive call to SNESSolve().

    1239: .keywords: SNES, nonlinear, get, number, unsuccessful, steps

    1241: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
    1242: @*/
    1243: PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
    1244: {
    1248:   *nfails = snes->numLinearSolveFailures;
    1249:   return(0);
    1250: }

    1254: /*@
    1255:    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
    1256:    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE

    1258:    Logically Collective on SNES

    1260:    Input Parameters:
    1261: +  snes     - SNES context
    1262: -  maxFails - maximum allowed linear solve failures

    1264:    Level: intermediate

    1266:    Options Database Keys:
    1267: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

    1269:    Notes: By default this is 0; that is SNES returns on the first failed linear solve

    1271: .keywords: SNES, nonlinear, set, maximum, unsuccessful, steps

    1273: .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
    1274: @*/
    1275: PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
    1276: {
    1280:   snes->maxLinearSolveFailures = maxFails;
    1281:   return(0);
    1282: }

    1286: /*@
    1287:    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
    1288:      are allowed before SNES terminates

    1290:    Not Collective

    1292:    Input Parameter:
    1293: .  snes     - SNES context

    1295:    Output Parameter:
    1296: .  maxFails - maximum of unsuccessful solves allowed

    1298:    Level: intermediate

    1300:    Notes: By default this is 1; that is SNES returns on the first failed linear solve

    1302: .keywords: SNES, nonlinear, get, maximum, unsuccessful, steps

    1304: .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
    1305: @*/
    1306: PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
    1307: {
    1311:   *maxFails = snes->maxLinearSolveFailures;
    1312:   return(0);
    1313: }

    1317: /*@
    1318:    SNESGetLinearSolveIterations - Gets the total number of linear iterations
    1319:    used by the nonlinear solver.

    1321:    Not Collective

    1323:    Input Parameter:
    1324: .  snes - SNES context

    1326:    Output Parameter:
    1327: .  lits - number of linear iterations

    1329:    Notes:
    1330:    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.

    1332:    Level: intermediate

    1334: .keywords: SNES, nonlinear, get, number, linear, iterations

    1336: .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
    1337: @*/
    1338: PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
    1339: {
    1343:   *lits = snes->linear_its;
    1344:   return(0);
    1345: }

    1349: /*@
    1350:    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
    1351:    are reset every time SNESSolve() is called.

    1353:    Logically Collective on SNES

    1355:    Input Parameter:
    1356: +  snes - SNES context
    1357: -  reset - whether to reset the counters or not

    1359:    Notes:
    1360:    This defaults to PETSC_TRUE

    1362:    Level: developer

    1364: .keywords: SNES, nonlinear, set, reset, number, linear, iterations

    1366: .seealso:  SNESGetNumberFunctionEvals(), SNESGetLinearSolveIterations(), SNESGetNPC()
    1367: @*/
    1368: PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
    1369: {
    1373:   snes->counters_reset = reset;
    1374:   return(0);
    1375: }

    1380: /*@
    1381:    SNESSetKSP - Sets a KSP context for the SNES object to use

    1383:    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm

    1385:    Input Parameters:
    1386: +  snes - the SNES context
    1387: -  ksp - the KSP context

    1389:    Notes:
    1390:    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
    1391:    so this routine is rarely needed.

    1393:    The KSP object that is already in the SNES object has its reference count
    1394:    decreased by one.

    1396:    Level: developer

    1398: .keywords: SNES, nonlinear, get, KSP, context

    1400: .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
    1401: @*/
    1402: PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
    1403: {

    1410:   PetscObjectReference((PetscObject)ksp);
    1411:   if (snes->ksp) {PetscObjectDereference((PetscObject)snes->ksp);}
    1412:   snes->ksp = ksp;
    1413:   return(0);
    1414: }

    1416: /* -----------------------------------------------------------*/
    1419: /*@
    1420:    SNESCreate - Creates a nonlinear solver context.

    1422:    Collective on MPI_Comm

    1424:    Input Parameters:
    1425: .  comm - MPI communicator

    1427:    Output Parameter:
    1428: .  outsnes - the new SNES context

    1430:    Options Database Keys:
    1431: +   -snes_mf - Activates default matrix-free Jacobian-vector products,
    1432:                and no preconditioning matrix
    1433: .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
    1434:                products, and a user-provided preconditioning matrix
    1435:                as set by SNESSetJacobian()
    1436: -   -snes_fd - Uses (slow!) finite differences to compute Jacobian

    1438:    Level: beginner

    1440: .keywords: SNES, nonlinear, create, context

    1442: .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()

    1444: @*/
    1445: PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
    1446: {
    1448:   SNES           snes;
    1449:   SNESKSPEW      *kctx;

    1453:   *outsnes = NULL;
    1454:   SNESInitializePackage();

    1456:   PetscHeaderCreate(snes,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);

    1458:   snes->ops->converged    = SNESConvergedDefault;
    1459:   snes->usesksp           = PETSC_TRUE;
    1460:   snes->tolerancesset     = PETSC_FALSE;
    1461:   snes->max_its           = 50;
    1462:   snes->max_funcs         = 10000;
    1463:   snes->norm              = 0.0;
    1464:   snes->normschedule      = SNES_NORM_ALWAYS;
    1465:   snes->functype          = SNES_FUNCTION_DEFAULT;
    1466: #if defined(PETSC_USE_REAL_SINGLE)
    1467:   snes->rtol              = 1.e-5;
    1468: #else
    1469:   snes->rtol              = 1.e-8;
    1470: #endif
    1471:   snes->ttol              = 0.0;
    1472: #if defined(PETSC_USE_REAL_SINGLE)
    1473:   snes->abstol            = 1.e-25;
    1474: #else
    1475:   snes->abstol            = 1.e-50;
    1476: #endif
    1477:   snes->stol              = 1.e-8;
    1478: #if defined(PETSC_USE_REAL_SINGLE)
    1479:   snes->deltatol          = 1.e-6;
    1480: #else
    1481:   snes->deltatol          = 1.e-12;
    1482: #endif
    1483:   snes->nfuncs            = 0;
    1484:   snes->numFailures       = 0;
    1485:   snes->maxFailures       = 1;
    1486:   snes->linear_its        = 0;
    1487:   snes->lagjacobian       = 1;
    1488:   snes->jac_iter          = 0;
    1489:   snes->lagjac_persist    = PETSC_FALSE;
    1490:   snes->lagpreconditioner = 1;
    1491:   snes->pre_iter          = 0;
    1492:   snes->lagpre_persist    = PETSC_FALSE;
    1493:   snes->numbermonitors    = 0;
    1494:   snes->data              = 0;
    1495:   snes->setupcalled       = PETSC_FALSE;
    1496:   snes->ksp_ewconv        = PETSC_FALSE;
    1497:   snes->nwork             = 0;
    1498:   snes->work              = 0;
    1499:   snes->nvwork            = 0;
    1500:   snes->vwork             = 0;
    1501:   snes->conv_hist_len     = 0;
    1502:   snes->conv_hist_max     = 0;
    1503:   snes->conv_hist         = NULL;
    1504:   snes->conv_hist_its     = NULL;
    1505:   snes->conv_hist_reset   = PETSC_TRUE;
    1506:   snes->counters_reset    = PETSC_TRUE;
    1507:   snes->vec_func_init_set = PETSC_FALSE;
    1508:   snes->reason            = SNES_CONVERGED_ITERATING;
    1509:   snes->pcside            = PC_RIGHT;

    1511:   snes->mf          = PETSC_FALSE;
    1512:   snes->mf_operator = PETSC_FALSE;
    1513:   snes->mf_version  = 1;

    1515:   snes->numLinearSolveFailures = 0;
    1516:   snes->maxLinearSolveFailures = 1;

    1518:   snes->vizerotolerance = 1.e-8;

    1520:   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
    1521:   PetscNewLog(snes,&kctx);

    1523:   snes->kspconvctx  = (void*)kctx;
    1524:   kctx->version     = 2;
    1525:   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
    1526:                              this was too large for some test cases */
    1527:   kctx->rtol_last   = 0.0;
    1528:   kctx->rtol_max    = .9;
    1529:   kctx->gamma       = 1.0;
    1530:   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
    1531:   kctx->alpha2      = kctx->alpha;
    1532:   kctx->threshold   = .1;
    1533:   kctx->lresid_last = 0.0;
    1534:   kctx->norm_last   = 0.0;

    1536:   *outsnes = snes;
    1537:   return(0);
    1538: }

    1540: /*MC
    1541:     SNESFunction - Functional form used to convey the nonlinear function to be solved by SNES

    1543:      Synopsis:
    1544:      #include "petscsnes.h"
    1545:      PetscErrorCode SNESFunction(SNES snes,Vec x,Vec f,void *ctx);

    1547:      Input Parameters:
    1548: +     snes - the SNES context
    1549: .     x    - state at which to evaluate residual
    1550: -     ctx     - optional user-defined function context, passed in with SNESSetFunction()

    1552:      Output Parameter:
    1553: .     f  - vector to put residual (function value)

    1555:    Level: intermediate

    1557: .seealso:   SNESSetFunction(), SNESGetFunction()
    1558: M*/

    1562: /*@C
    1563:    SNESSetFunction - Sets the function evaluation routine and function
    1564:    vector for use by the SNES routines in solving systems of nonlinear
    1565:    equations.

    1567:    Logically Collective on SNES

    1569:    Input Parameters:
    1570: +  snes - the SNES context
    1571: .  r - vector to store function value
    1572: .  f - function evaluation routine; see SNESFunction for calling sequence details
    1573: -  ctx - [optional] user-defined context for private data for the
    1574:          function evaluation routine (may be NULL)

    1576:    Notes:
    1577:    The Newton-like methods typically solve linear systems of the form
    1578: $      f'(x) x = -f(x),
    1579:    where f'(x) denotes the Jacobian matrix and f(x) is the function.

    1581:    Level: beginner

    1583: .keywords: SNES, nonlinear, set, function

    1585: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
    1586: @*/
    1587: PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
    1588: {
    1590:   DM             dm;

    1594:   if (r) {
    1597:     PetscObjectReference((PetscObject)r);
    1598:     VecDestroy(&snes->vec_func);

    1600:     snes->vec_func = r;
    1601:   }
    1602:   SNESGetDM(snes,&dm);
    1603:   DMSNESSetFunction(dm,f,ctx);
    1604:   return(0);
    1605: }

    1610: /*@C
    1611:    SNESSetInitialFunction - Sets the function vector to be used as the
    1612:    function norm at the initialization of the method.  In some
    1613:    instances, the user has precomputed the function before calling
    1614:    SNESSolve.  This function allows one to avoid a redundant call
    1615:    to SNESComputeFunction in that case.

    1617:    Logically Collective on SNES

    1619:    Input Parameters:
    1620: +  snes - the SNES context
    1621: -  f - vector to store function value

    1623:    Notes:
    1624:    This should not be modified during the solution procedure.

    1626:    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.

    1628:    Level: developer

    1630: .keywords: SNES, nonlinear, set, function

    1632: .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
    1633: @*/
    1634: PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
    1635: {
    1637:   Vec            vec_func;

    1643:   if (snes->pcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
    1644:     snes->vec_func_init_set = PETSC_FALSE;
    1645:     return(0);
    1646:   }
    1647:   SNESGetFunction(snes,&vec_func,NULL,NULL);
    1648:   VecCopy(f, vec_func);

    1650:   snes->vec_func_init_set = PETSC_TRUE;
    1651:   return(0);
    1652: }

    1656: /*@
    1657:    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
    1658:    of the SNES method.

    1660:    Logically Collective on SNES

    1662:    Input Parameters:
    1663: +  snes - the SNES context
    1664: -  normschedule - the frequency of norm computation

    1666:    Options Database Key:
    1667: .  -snes_norm_schedule <none, always, initialonly, finalonly, initalfinalonly>

    1669:    Notes:
    1670:    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
    1671:    of the nonlinear function and the taking of its norm at every iteration to
    1672:    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
    1673:    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
    1674:    may either be monitored for convergence or not.  As these are often used as nonlinear
    1675:    preconditioners, monitoring the norm of their error is not a useful enterprise within
    1676:    their solution.

    1678:    Level: developer

    1680: .keywords: SNES, nonlinear, set, function, norm, type

    1682: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
    1683: @*/
    1684: PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
    1685: {
    1688:   snes->normschedule = normschedule;
    1689:   return(0);
    1690: }

    1695: /*@
    1696:    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
    1697:    of the SNES method.

    1699:    Logically Collective on SNES

    1701:    Input Parameters:
    1702: +  snes - the SNES context
    1703: -  normschedule - the type of the norm used

    1705:    Level: advanced

    1707: .keywords: SNES, nonlinear, set, function, norm, type

    1709: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
    1710: @*/
    1711: PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
    1712: {
    1715:   *normschedule = snes->normschedule;
    1716:   return(0);
    1717: }

    1722: /*@C
    1723:    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
    1724:    of the SNES method.

    1726:    Logically Collective on SNES

    1728:    Input Parameters:
    1729: +  snes - the SNES context
    1730: -  normschedule - the frequency of norm computation

    1732:    Notes:
    1733:    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
    1734:    of the nonlinear function and the taking of its norm at every iteration to
    1735:    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
    1736:    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
    1737:    may either be monitored for convergence or not.  As these are often used as nonlinear
    1738:    preconditioners, monitoring the norm of their error is not a useful enterprise within
    1739:    their solution.

    1741:    Level: developer

    1743: .keywords: SNES, nonlinear, set, function, norm, type

    1745: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
    1746: @*/
    1747: PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
    1748: {
    1751:   snes->functype = type;
    1752:   return(0);
    1753: }

    1758: /*@C
    1759:    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
    1760:    of the SNES method.

    1762:    Logically Collective on SNES

    1764:    Input Parameters:
    1765: +  snes - the SNES context
    1766: -  normschedule - the type of the norm used

    1768:    Level: advanced

    1770: .keywords: SNES, nonlinear, set, function, norm, type

    1772: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
    1773: @*/
    1774: PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
    1775: {
    1778:   *type = snes->functype;
    1779:   return(0);
    1780: }

    1782: /*MC
    1783:     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function

    1785:      Synopsis:
    1786:      #include <petscsnes.h>
    1787: $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);

    1789: +  X   - solution vector
    1790: .  B   - RHS vector
    1791: -  ctx - optional user-defined Gauss-Seidel context

    1793:    Level: intermediate

    1795: .seealso:   SNESSetNGS(), SNESGetNGS()
    1796: M*/

    1800: /*@C
    1801:    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
    1802:    use with composed nonlinear solvers.

    1804:    Input Parameters:
    1805: +  snes   - the SNES context
    1806: .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
    1807: -  ctx    - [optional] user-defined context for private data for the
    1808:             smoother evaluation routine (may be NULL)

    1810:    Notes:
    1811:    The NGS routines are used by the composed nonlinear solver to generate
    1812:     a problem appropriate update to the solution, particularly FAS.

    1814:    Level: intermediate

    1816: .keywords: SNES, nonlinear, set, Gauss-Seidel

    1818: .seealso: SNESGetFunction(), SNESComputeNGS()
    1819: @*/
    1820: PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
    1821: {
    1823:   DM             dm;

    1827:   SNESGetDM(snes,&dm);
    1828:   DMSNESSetNGS(dm,f,ctx);
    1829:   return(0);
    1830: }

    1834: PETSC_EXTERN PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
    1835: {
    1837:   DM             dm;
    1838:   DMSNES         sdm;

    1841:   SNESGetDM(snes,&dm);
    1842:   DMGetDMSNES(dm,&sdm);
    1843:   /*  A(x)*x - b(x) */
    1844:   if (sdm->ops->computepfunction) {
    1845:     (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);
    1846:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");

    1848:   if (sdm->ops->computepjacobian) {
    1849:     (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);
    1850:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard matrix.");
    1851:   VecScale(f,-1.0);
    1852:   MatMultAdd(snes->jacobian,x,f,f);
    1853:   return(0);
    1854: }

    1858: PETSC_EXTERN PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
    1859: {
    1861:   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
    1862:   return(0);
    1863: }

    1867: /*@C
    1868:    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)

    1870:    Logically Collective on SNES

    1872:    Input Parameters:
    1873: +  snes - the SNES context
    1874: .  r - vector to store function value
    1875: .  b - function evaluation routine
    1876: .  Amat - matrix with which A(x) x - b(x) is to be computed
    1877: .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
    1878: .  J  - function to compute matrix value, see SNESJacobianFunction for details on its calling sequence
    1879: -  ctx - [optional] user-defined context for private data for the
    1880:          function evaluation routine (may be NULL)

    1882:    Notes:
    1883:     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
    1884:     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.

    1886:     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both

    1888: $     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}
    1889: $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.

    1891:      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.

    1893:    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
    1894:    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)

    1896:    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
    1897:    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
    1898:    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).

    1900:    Level: intermediate

    1902: .keywords: SNES, nonlinear, set, function

    1904: .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard(), SNESJacobianFunction
    1905: @*/
    1906: 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)
    1907: {
    1909:   DM             dm;

    1913:   SNESGetDM(snes, &dm);
    1914:   DMSNESSetPicard(dm,b,J,ctx);
    1915:   SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);
    1916:   SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);
    1917:   return(0);
    1918: }

    1922: /*@C
    1923:    SNESGetPicard - Returns the context for the Picard iteration

    1925:    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.

    1927:    Input Parameter:
    1928: .  snes - the SNES context

    1930:    Output Parameter:
    1931: +  r - the function (or NULL)
    1932: .  f - the function (or NULL); see SNESFunction for calling sequence details
    1933: .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
    1934: .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
    1935: .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
    1936: -  ctx - the function context (or NULL)

    1938:    Level: advanced

    1940: .keywords: SNES, nonlinear, get, function

    1942: .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
    1943: @*/
    1944: 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)
    1945: {
    1947:   DM             dm;

    1951:   SNESGetFunction(snes,r,NULL,NULL);
    1952:   SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);
    1953:   SNESGetDM(snes,&dm);
    1954:   DMSNESGetPicard(dm,f,J,ctx);
    1955:   return(0);
    1956: }

    1960: /*@C
    1961:    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem

    1963:    Logically Collective on SNES

    1965:    Input Parameters:
    1966: +  snes - the SNES context
    1967: .  func - function evaluation routine
    1968: -  ctx - [optional] user-defined context for private data for the
    1969:          function evaluation routine (may be NULL)

    1971:    Calling sequence of func:
    1972: $    func (SNES snes,Vec x,void *ctx);

    1974: .  f - function vector
    1975: -  ctx - optional user-defined function context

    1977:    Level: intermediate

    1979: .keywords: SNES, nonlinear, set, function

    1981: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
    1982: @*/
    1983: PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
    1984: {
    1987:   if (func) snes->ops->computeinitialguess = func;
    1988:   if (ctx)  snes->initialguessP            = ctx;
    1989:   return(0);
    1990: }

    1992: /* --------------------------------------------------------------- */
    1995: /*@C
    1996:    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
    1997:    it assumes a zero right hand side.

    1999:    Logically Collective on SNES

    2001:    Input Parameter:
    2002: .  snes - the SNES context

    2004:    Output Parameter:
    2005: .  rhs - the right hand side vector or NULL if the right hand side vector is null

    2007:    Level: intermediate

    2009: .keywords: SNES, nonlinear, get, function, right hand side

    2011: .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
    2012: @*/
    2013: PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
    2014: {
    2018:   *rhs = snes->vec_rhs;
    2019:   return(0);
    2020: }

    2024: /*@
    2025:    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().

    2027:    Collective on SNES

    2029:    Input Parameters:
    2030: +  snes - the SNES context
    2031: -  x - input vector

    2033:    Output Parameter:
    2034: .  y - function vector, as set by SNESSetFunction()

    2036:    Notes:
    2037:    SNESComputeFunction() is typically used within nonlinear solvers
    2038:    implementations, so most users would not generally call this routine
    2039:    themselves.

    2041:    Level: developer

    2043: .keywords: SNES, nonlinear, compute, function

    2045: .seealso: SNESSetFunction(), SNESGetFunction()
    2046: @*/
    2047: PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
    2048: {
    2050:   DM             dm;
    2051:   DMSNES         sdm;

    2059:   VecValidValues(x,2,PETSC_TRUE);

    2061:   SNESGetDM(snes,&dm);
    2062:   DMGetDMSNES(dm,&sdm);
    2063:   if (sdm->ops->computefunction) {
    2064:     PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);
    2065:     VecLockPush(x);
    2066:     PetscStackPush("SNES user function");
    2067:     (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);
    2068:     PetscStackPop;
    2069:     VecLockPop(x);
    2070:     PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);
    2071:   } else if (snes->vec_rhs) {
    2072:     MatMult(snes->jacobian, x, y);
    2073:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
    2074:   if (snes->vec_rhs) {
    2075:     VecAXPY(y,-1.0,snes->vec_rhs);
    2076:   }
    2077:   snes->nfuncs++;
    2078:   /*
    2079:      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
    2080:      propagate the value to all processes
    2081:   */
    2082:   if (snes->domainerror) {
    2083:     VecSetInf(y);
    2084:   }
    2085:   return(0);
    2086: }

    2090: /*@
    2091:    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().

    2093:    Collective on SNES

    2095:    Input Parameters:
    2096: +  snes - the SNES context
    2097: .  x - input vector
    2098: -  b - rhs vector

    2100:    Output Parameter:
    2101: .  x - new solution vector

    2103:    Notes:
    2104:    SNESComputeNGS() is typically used within composed nonlinear solver
    2105:    implementations, so most users would not generally call this routine
    2106:    themselves.

    2108:    Level: developer

    2110: .keywords: SNES, nonlinear, compute, function

    2112: .seealso: SNESSetNGS(), SNESComputeFunction()
    2113: @*/
    2114: PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
    2115: {
    2117:   DM             dm;
    2118:   DMSNES         sdm;

    2126:   if (b) {VecValidValues(b,2,PETSC_TRUE);}
    2127:   PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);
    2128:   SNESGetDM(snes,&dm);
    2129:   DMGetDMSNES(dm,&sdm);
    2130:   if (sdm->ops->computegs) {
    2131:     if (b) {VecLockPush(b);}
    2132:     PetscStackPush("SNES user NGS");
    2133:     (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);
    2134:     PetscStackPop;
    2135:     if (b) {VecLockPop(b);}
    2136:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
    2137:   PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);
    2138:   return(0);
    2139: }

    2143: /*@
    2144:    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().

    2146:    Collective on SNES and Mat

    2148:    Input Parameters:
    2149: +  snes - the SNES context
    2150: -  x - input vector

    2152:    Output Parameters:
    2153: +  A - Jacobian matrix
    2154: -  B - optional preconditioning matrix

    2156:   Options Database Keys:
    2157: +    -snes_lag_preconditioner <lag>
    2158: .    -snes_lag_jacobian <lag>
    2159: .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
    2160: .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
    2161: .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
    2162: .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
    2163: .    -snes_compare_coloring - Compute the finite differece Jacobian using coloring and display norms of difference
    2164: .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
    2165: .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
    2166: .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
    2167: .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
    2168: .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
    2169: -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences

    2172:    Notes:
    2173:    Most users should not need to explicitly call this routine, as it
    2174:    is used internally within the nonlinear solvers.

    2176:    Level: developer

    2178: .keywords: SNES, compute, Jacobian, matrix

    2180: .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
    2181: @*/
    2182: PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
    2183: {
    2185:   PetscBool      flag;
    2186:   DM             dm;
    2187:   DMSNES         sdm;
    2188:   KSP            ksp;

    2194:   VecValidValues(X,2,PETSC_TRUE);
    2195:   SNESGetDM(snes,&dm);
    2196:   DMGetDMSNES(dm,&sdm);

    2198:   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");

    2200:   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */

    2202:   if (snes->lagjacobian == -2) {
    2203:     snes->lagjacobian = -1;

    2205:     PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");
    2206:   } else if (snes->lagjacobian == -1) {
    2207:     PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");
    2208:     PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);
    2209:     if (flag) {
    2210:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
    2211:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
    2212:     }
    2213:     return(0);
    2214:   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
    2215:     PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);
    2216:     PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);
    2217:     if (flag) {
    2218:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
    2219:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
    2220:     }
    2221:     return(0);
    2222:   }
    2223:   if (snes->pc && snes->pcside == PC_LEFT) {
    2224:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
    2225:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
    2226:       return(0);
    2227:   }

    2229:   PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);
    2230:   VecLockPush(X);
    2231:   PetscStackPush("SNES user Jacobian function");
    2232:   (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);
    2233:   PetscStackPop;
    2234:   VecLockPop(X);
    2235:   PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);

    2237:   /* the next line ensures that snes->ksp exists */
    2238:   SNESGetKSP(snes,&ksp);
    2239:   if (snes->lagpreconditioner == -2) {
    2240:     PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");
    2241:     KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);
    2242:     snes->lagpreconditioner = -1;
    2243:   } else if (snes->lagpreconditioner == -1) {
    2244:     PetscInfo(snes,"Reusing preconditioner because lag is -1\n");
    2245:     KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);
    2246:   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
    2247:     PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);
    2248:     KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);
    2249:   } else {
    2250:     PetscInfo(snes,"Rebuilding preconditioner\n");
    2251:     KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);
    2252:   }

    2254:   /* make sure user returned a correct Jacobian and preconditioner */
    2257:   {
    2258:     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
    2259:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit",&flag,NULL);
    2260:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",&flag_draw,NULL);
    2261:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",&flag_contour,NULL);
    2262:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_operator",&flag_operator,NULL);
    2263:     if (flag || flag_draw || flag_contour) {
    2264:       Mat          Bexp_mine = NULL,Bexp,FDexp;
    2265:       PetscViewer  vdraw,vstdout;
    2266:       PetscBool    flg;
    2267:       if (flag_operator) {
    2268:         MatComputeExplicitOperator(A,&Bexp_mine);
    2269:         Bexp = Bexp_mine;
    2270:       } else {
    2271:         /* See if the preconditioning matrix can be viewed and added directly */
    2272:         PetscObjectTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");
    2273:         if (flg) Bexp = B;
    2274:         else {
    2275:           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
    2276:           MatComputeExplicitOperator(B,&Bexp_mine);
    2277:           Bexp = Bexp_mine;
    2278:         }
    2279:       }
    2280:       MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);
    2281:       SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);
    2282:       PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);
    2283:       if (flag_draw || flag_contour) {
    2284:         PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);
    2285:         if (flag_contour) {PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);}
    2286:       } else vdraw = NULL;
    2287:       PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");
    2288:       if (flag) {MatView(Bexp,vstdout);}
    2289:       if (vdraw) {MatView(Bexp,vdraw);}
    2290:       PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");
    2291:       if (flag) {MatView(FDexp,vstdout);}
    2292:       if (vdraw) {MatView(FDexp,vdraw);}
    2293:       MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);
    2294:       PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");
    2295:       if (flag) {MatView(FDexp,vstdout);}
    2296:       if (vdraw) {              /* Always use contour for the difference */
    2297:         PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
    2298:         MatView(FDexp,vdraw);
    2299:         PetscViewerPopFormat(vdraw);
    2300:       }
    2301:       if (flag_contour) {PetscViewerPopFormat(vdraw);}
    2302:       PetscViewerDestroy(&vdraw);
    2303:       MatDestroy(&Bexp_mine);
    2304:       MatDestroy(&FDexp);
    2305:     }
    2306:   }
    2307:   {
    2308:     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
    2309:     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
    2310:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring",&flag,NULL);
    2311:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_display",&flag_display,NULL);
    2312:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",&flag_draw,NULL);
    2313:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",&flag_contour,NULL);
    2314:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",&flag_threshold,NULL);
    2315:     PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);
    2316:     PetscOptionsGetReal(((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);
    2317:     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
    2318:       Mat            Bfd;
    2319:       PetscViewer    vdraw,vstdout;
    2320:       MatColoring    coloring;
    2321:       ISColoring     iscoloring;
    2322:       MatFDColoring  matfdcoloring;
    2323:       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
    2324:       void           *funcctx;
    2325:       PetscReal      norm1,norm2,normmax;

    2327:       MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);
    2328:       MatColoringCreate(Bfd,&coloring);
    2329:       MatColoringSetType(coloring,MATCOLORINGSL);
    2330:       MatColoringSetFromOptions(coloring);
    2331:       MatColoringApply(coloring,&iscoloring);
    2332:       MatColoringDestroy(&coloring);
    2333:       MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);
    2334:       MatFDColoringSetFromOptions(matfdcoloring);
    2335:       MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);
    2336:       ISColoringDestroy(&iscoloring);

    2338:       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
    2339:       SNESGetFunction(snes,NULL,&func,&funcctx);
    2340:       MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);
    2341:       PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);
    2342:       PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");
    2343:       MatFDColoringSetFromOptions(matfdcoloring);
    2344:       MatFDColoringApply(Bfd,matfdcoloring,X,snes);
    2345:       MatFDColoringDestroy(&matfdcoloring);

    2347:       PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);
    2348:       if (flag_draw || flag_contour) {
    2349:         PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),0,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);
    2350:         if (flag_contour) {PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);}
    2351:       } else vdraw = NULL;
    2352:       PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");
    2353:       if (flag_display) {MatView(B,vstdout);}
    2354:       if (vdraw) {MatView(B,vdraw);}
    2355:       PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");
    2356:       if (flag_display) {MatView(Bfd,vstdout);}
    2357:       if (vdraw) {MatView(Bfd,vdraw);}
    2358:       MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);
    2359:       MatNorm(Bfd,NORM_1,&norm1);
    2360:       MatNorm(Bfd,NORM_FROBENIUS,&norm2);
    2361:       MatNorm(Bfd,NORM_MAX,&normmax);
    2362:       PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%g normFrob=%g normmax=%g\n",(double)norm1,(double)norm2,(double)normmax);
    2363:       if (flag_display) {MatView(Bfd,vstdout);}
    2364:       if (vdraw) {              /* Always use contour for the difference */
    2365:         PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
    2366:         MatView(Bfd,vdraw);
    2367:         PetscViewerPopFormat(vdraw);
    2368:       }
    2369:       if (flag_contour) {PetscViewerPopFormat(vdraw);}

    2371:       if (flag_threshold) {
    2372:         PetscInt bs,rstart,rend,i;
    2373:         MatGetBlockSize(B,&bs);
    2374:         MatGetOwnershipRange(B,&rstart,&rend);
    2375:         for (i=rstart; i<rend; i++) {
    2376:           const PetscScalar *ba,*ca;
    2377:           const PetscInt    *bj,*cj;
    2378:           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
    2379:           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
    2380:           MatGetRow(B,i,&bn,&bj,&ba);
    2381:           MatGetRow(Bfd,i,&cn,&cj,&ca);
    2382:           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
    2383:           for (j=0; j<bn; j++) {
    2384:             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
    2385:             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
    2386:               maxentrycol = bj[j];
    2387:               maxentry    = PetscRealPart(ba[j]);
    2388:             }
    2389:             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
    2390:               maxdiffcol = bj[j];
    2391:               maxdiff    = PetscRealPart(ca[j]);
    2392:             }
    2393:             if (rdiff > maxrdiff) {
    2394:               maxrdiffcol = bj[j];
    2395:               maxrdiff    = rdiff;
    2396:             }
    2397:           }
    2398:           if (maxrdiff > 1) {
    2399:             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);
    2400:             for (j=0; j<bn; j++) {
    2401:               PetscReal rdiff;
    2402:               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
    2403:               if (rdiff > 1) {
    2404:                 PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));
    2405:               }
    2406:             }
    2407:             PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);
    2408:           }
    2409:           MatRestoreRow(B,i,&bn,&bj,&ba);
    2410:           MatRestoreRow(Bfd,i,&cn,&cj,&ca);
    2411:         }
    2412:       }
    2413:       PetscViewerDestroy(&vdraw);
    2414:       MatDestroy(&Bfd);
    2415:     }
    2416:   }
    2417:   return(0);
    2418: }

    2420: /*MC
    2421:     SNESJacobianFunction - Function used to convey the nonlinear Jacobian of the function to be solved by SNES

    2423:      Synopsis:
    2424:      #include "petscsnes.h"
    2425:      PetscErrorCode SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);

    2427: +  x - input vector
    2428: .  Amat - the matrix that defines the (approximate) Jacobian
    2429: .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
    2430: -  ctx - [optional] user-defined Jacobian context

    2432:    Level: intermediate

    2434: .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
    2435: M*/

    2439: /*@C
    2440:    SNESSetJacobian - Sets the function to compute Jacobian as well as the
    2441:    location to store the matrix.

    2443:    Logically Collective on SNES and Mat

    2445:    Input Parameters:
    2446: +  snes - the SNES context
    2447: .  Amat - the matrix that defines the (approximate) Jacobian
    2448: .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
    2449: .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value), see SNESJacobianFunction for details
    2450: -  ctx - [optional] user-defined context for private data for the
    2451:          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)

    2453:    Notes:
    2454:    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
    2455:    each matrix.

    2457:    If you know the operator Amat has a null space you can use MatSetNullSpace() and MatSetTransposeNullSpace() to supply the null
    2458:    space to Amat and the KSP solvers will automatically use that null space as needed during the solution process.

    2460:    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
    2461:    must be a MatFDColoring.

    2463:    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
    2464:    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.

    2466:    Level: beginner

    2468: .keywords: SNES, nonlinear, set, Jacobian, matrix

    2470: .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J,
    2471:           SNESSetPicard(), SNESJacobianFunction
    2472: @*/
    2473: PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
    2474: {
    2476:   DM             dm;

    2484:   SNESGetDM(snes,&dm);
    2485:   DMSNESSetJacobian(dm,J,ctx);
    2486:   if (Amat) {
    2487:     PetscObjectReference((PetscObject)Amat);
    2488:     MatDestroy(&snes->jacobian);

    2490:     snes->jacobian = Amat;
    2491:   }
    2492:   if (Pmat) {
    2493:     PetscObjectReference((PetscObject)Pmat);
    2494:     MatDestroy(&snes->jacobian_pre);

    2496:     snes->jacobian_pre = Pmat;
    2497:   }
    2498:   return(0);
    2499: }

    2503: /*@C
    2504:    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
    2505:    provided context for evaluating the Jacobian.

    2507:    Not Collective, but Mat object will be parallel if SNES object is

    2509:    Input Parameter:
    2510: .  snes - the nonlinear solver context

    2512:    Output Parameters:
    2513: +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
    2514: .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
    2515: .  J - location to put Jacobian function (or NULL), see SNESJacobianFunction for details on its calling sequence
    2516: -  ctx - location to stash Jacobian ctx (or NULL)

    2518:    Level: advanced

    2520: .seealso: SNESSetJacobian(), SNESComputeJacobian(), SNESJacobianFunction, SNESGetFunction()
    2521: @*/
    2522: PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
    2523: {
    2525:   DM             dm;
    2526:   DMSNES         sdm;

    2530:   if (Amat) *Amat = snes->jacobian;
    2531:   if (Pmat) *Pmat = snes->jacobian_pre;
    2532:   SNESGetDM(snes,&dm);
    2533:   DMGetDMSNES(dm,&sdm);
    2534:   if (J) *J = sdm->ops->computejacobian;
    2535:   if (ctx) *ctx = sdm->jacobianctx;
    2536:   return(0);
    2537: }

    2541: /*@
    2542:    SNESSetUp - Sets up the internal data structures for the later use
    2543:    of a nonlinear solver.

    2545:    Collective on SNES

    2547:    Input Parameters:
    2548: .  snes - the SNES context

    2550:    Notes:
    2551:    For basic use of the SNES solvers the user need not explicitly call
    2552:    SNESSetUp(), since these actions will automatically occur during
    2553:    the call to SNESSolve().  However, if one wishes to control this
    2554:    phase separately, SNESSetUp() should be called after SNESCreate()
    2555:    and optional routines of the form SNESSetXXX(), but before SNESSolve().

    2557:    Level: advanced

    2559: .keywords: SNES, nonlinear, setup

    2561: .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
    2562: @*/
    2563: PetscErrorCode  SNESSetUp(SNES snes)
    2564: {
    2566:   DM             dm;
    2567:   DMSNES         sdm;
    2568:   SNESLineSearch linesearch, pclinesearch;
    2569:   void           *lsprectx,*lspostctx;
    2570:   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
    2571:   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
    2572:   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
    2573:   Vec            f,fpc;
    2574:   void           *funcctx;
    2575:   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
    2576:   void           *jacctx,*appctx;
    2577:   Mat            j,jpre;

    2581:   if (snes->setupcalled) return(0);

    2583:   if (!((PetscObject)snes)->type_name) {
    2584:     SNESSetType(snes,SNESNEWTONLS);
    2585:   }

    2587:   SNESGetFunction(snes,&snes->vec_func,NULL,NULL);

    2589:   SNESGetDM(snes,&dm);
    2590:   DMGetDMSNES(dm,&sdm);
    2591:   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
    2592:   if (!sdm->ops->computejacobian) {
    2593:     DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);
    2594:   }
    2595:   if (!snes->vec_func) {
    2596:     DMCreateGlobalVector(dm,&snes->vec_func);
    2597:   }

    2599:   if (!snes->ksp) {
    2600:     SNESGetKSP(snes, &snes->ksp);
    2601:   }

    2603:   if (!snes->linesearch) {
    2604:     SNESGetLineSearch(snes, &snes->linesearch);
    2605:   }
    2606:   SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);

    2608:   if (snes->pc && (snes->pcside == PC_LEFT)) {
    2609:     snes->mf          = PETSC_TRUE;
    2610:     snes->mf_operator = PETSC_FALSE;
    2611:   }

    2613:   if (snes->pc) {
    2614:     /* copy the DM over */
    2615:     SNESGetDM(snes,&dm);
    2616:     SNESSetDM(snes->pc,dm);

    2618:     SNESGetFunction(snes,&f,&func,&funcctx);
    2619:     VecDuplicate(f,&fpc);
    2620:     SNESSetFunction(snes->pc,fpc,func,funcctx);
    2621:     SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);
    2622:     SNESSetJacobian(snes->pc,j,jpre,jac,jacctx);
    2623:     SNESGetApplicationContext(snes,&appctx);
    2624:     SNESSetApplicationContext(snes->pc,appctx);
    2625:     VecDestroy(&fpc);

    2627:     /* copy the function pointers over */
    2628:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->pc);

    2630:     /* default to 1 iteration */
    2631:     SNESSetTolerances(snes->pc,0.0,0.0,0.0,1,snes->pc->max_funcs);
    2632:     if (snes->pcside==PC_RIGHT) {
    2633:       SNESSetNormSchedule(snes->pc,SNES_NORM_FINAL_ONLY);
    2634:     } else {
    2635:       SNESSetNormSchedule(snes->pc,SNES_NORM_NONE);
    2636:     }
    2637:     SNESSetFromOptions(snes->pc);

    2639:     /* copy the line search context over */
    2640:     SNESGetLineSearch(snes,&linesearch);
    2641:     SNESGetLineSearch(snes->pc,&pclinesearch);
    2642:     SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
    2643:     SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
    2644:     SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);
    2645:     SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);
    2646:     PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);
    2647:   }
    2648:   if (snes->mf) {
    2649:     SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);
    2650:   }
    2651:   if (snes->ops->usercompute && !snes->user) {
    2652:     (*snes->ops->usercompute)(snes,(void**)&snes->user);
    2653:   }

    2655:   snes->jac_iter = 0;
    2656:   snes->pre_iter = 0;

    2658:   if (snes->ops->setup) {
    2659:     (*snes->ops->setup)(snes);
    2660:   }

    2662:   if (snes->pc && (snes->pcside == PC_LEFT)) {
    2663:     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
    2664:       SNESGetLineSearch(snes,&linesearch);
    2665:       SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);
    2666:     }
    2667:   }

    2669:   snes->setupcalled = PETSC_TRUE;
    2670:   return(0);
    2671: }

    2675: /*@
    2676:    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats

    2678:    Collective on SNES

    2680:    Input Parameter:
    2681: .  snes - iterative context obtained from SNESCreate()

    2683:    Level: intermediate

    2685:    Notes: Also calls the application context destroy routine set with SNESSetComputeApplicationContext()

    2687: .keywords: SNES, destroy

    2689: .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
    2690: @*/
    2691: PetscErrorCode  SNESReset(SNES snes)
    2692: {

    2697:   if (snes->ops->userdestroy && snes->user) {
    2698:     (*snes->ops->userdestroy)((void**)&snes->user);
    2699:     snes->user = NULL;
    2700:   }
    2701:   if (snes->pc) {
    2702:     SNESReset(snes->pc);
    2703:   }

    2705:   if (snes->ops->reset) {
    2706:     (*snes->ops->reset)(snes);
    2707:   }
    2708:   if (snes->ksp) {
    2709:     KSPReset(snes->ksp);
    2710:   }

    2712:   if (snes->linesearch) {
    2713:     SNESLineSearchReset(snes->linesearch);
    2714:   }

    2716:   VecDestroy(&snes->vec_rhs);
    2717:   VecDestroy(&snes->vec_sol);
    2718:   VecDestroy(&snes->vec_sol_update);
    2719:   VecDestroy(&snes->vec_func);
    2720:   MatDestroy(&snes->jacobian);
    2721:   MatDestroy(&snes->jacobian_pre);
    2722:   VecDestroyVecs(snes->nwork,&snes->work);
    2723:   VecDestroyVecs(snes->nvwork,&snes->vwork);

    2725:   snes->nwork       = snes->nvwork = 0;
    2726:   snes->setupcalled = PETSC_FALSE;
    2727:   return(0);
    2728: }

    2732: /*@
    2733:    SNESDestroy - Destroys the nonlinear solver context that was created
    2734:    with SNESCreate().

    2736:    Collective on SNES

    2738:    Input Parameter:
    2739: .  snes - the SNES context

    2741:    Level: beginner

    2743: .keywords: SNES, nonlinear, destroy

    2745: .seealso: SNESCreate(), SNESSolve()
    2746: @*/
    2747: PetscErrorCode  SNESDestroy(SNES *snes)
    2748: {

    2752:   if (!*snes) return(0);
    2754:   if (--((PetscObject)(*snes))->refct > 0) {*snes = 0; return(0);}

    2756:   SNESReset((*snes));
    2757:   SNESDestroy(&(*snes)->pc);

    2759:   /* if memory was published with SAWs then destroy it */
    2760:   PetscObjectSAWsViewOff((PetscObject)*snes);
    2761:   if ((*snes)->ops->destroy) {(*((*snes))->ops->destroy)((*snes));}

    2763:   DMDestroy(&(*snes)->dm);
    2764:   KSPDestroy(&(*snes)->ksp);
    2765:   SNESLineSearchDestroy(&(*snes)->linesearch);

    2767:   PetscFree((*snes)->kspconvctx);
    2768:   if ((*snes)->ops->convergeddestroy) {
    2769:     (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);
    2770:   }
    2771:   if ((*snes)->conv_malloc) {
    2772:     PetscFree((*snes)->conv_hist);
    2773:     PetscFree((*snes)->conv_hist_its);
    2774:   }
    2775:   SNESMonitorCancel((*snes));
    2776:   PetscHeaderDestroy(snes);
    2777:   return(0);
    2778: }

    2780: /* ----------- Routines to set solver parameters ---------- */

    2784: /*@
    2785:    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.

    2787:    Logically Collective on SNES

    2789:    Input Parameters:
    2790: +  snes - the SNES context
    2791: -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
    2792:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

    2794:    Options Database Keys:
    2795: .    -snes_lag_preconditioner <lag>

    2797:    Notes:
    2798:    The default is 1
    2799:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
    2800:    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use

    2802:    Level: intermediate

    2804: .keywords: SNES, nonlinear, set, convergence, tolerances

    2806: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()

    2808: @*/
    2809: PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
    2810: {
    2813:   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
    2814:   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
    2816:   snes->lagpreconditioner = lag;
    2817:   return(0);
    2818: }

    2822: /*@
    2823:    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does

    2825:    Logically Collective on SNES

    2827:    Input Parameters:
    2828: +  snes - the SNES context
    2829: -  steps - the number of refinements to do, defaults to 0

    2831:    Options Database Keys:
    2832: .    -snes_grid_sequence <steps>

    2834:    Level: intermediate

    2836:    Notes:
    2837:    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.

    2839: .keywords: SNES, nonlinear, set, convergence, tolerances

    2841: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetGridSequence()

    2843: @*/
    2844: PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
    2845: {
    2849:   snes->gridsequence = steps;
    2850:   return(0);
    2851: }

    2855: /*@
    2856:    SNESGetGridSequence - gets the number of steps of grid sequencing that SNES does

    2858:    Logically Collective on SNES

    2860:    Input Parameter:
    2861: .  snes - the SNES context

    2863:    Output Parameter:
    2864: .  steps - the number of refinements to do, defaults to 0

    2866:    Options Database Keys:
    2867: .    -snes_grid_sequence <steps>

    2869:    Level: intermediate

    2871:    Notes:
    2872:    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.

    2874: .keywords: SNES, nonlinear, set, convergence, tolerances

    2876: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetGridSequence()

    2878: @*/
    2879: PetscErrorCode  SNESGetGridSequence(SNES snes,PetscInt *steps)
    2880: {
    2883:   *steps = snes->gridsequence;
    2884:   return(0);
    2885: }

    2889: /*@
    2890:    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt

    2892:    Not Collective

    2894:    Input Parameter:
    2895: .  snes - the SNES context

    2897:    Output Parameter:
    2898: .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
    2899:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

    2901:    Options Database Keys:
    2902: .    -snes_lag_preconditioner <lag>

    2904:    Notes:
    2905:    The default is 1
    2906:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

    2908:    Level: intermediate

    2910: .keywords: SNES, nonlinear, set, convergence, tolerances

    2912: .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()

    2914: @*/
    2915: PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
    2916: {
    2919:   *lag = snes->lagpreconditioner;
    2920:   return(0);
    2921: }

    2925: /*@
    2926:    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
    2927:      often the preconditioner is rebuilt.

    2929:    Logically Collective on SNES

    2931:    Input Parameters:
    2932: +  snes - the SNES context
    2933: -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
    2934:          the Jacobian is built etc. -2 means rebuild at next chance but then never again

    2936:    Options Database Keys:
    2937: .    -snes_lag_jacobian <lag>

    2939:    Notes:
    2940:    The default is 1
    2941:    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
    2942:    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
    2943:    at the next Newton step but never again (unless it is reset to another value)

    2945:    Level: intermediate

    2947: .keywords: SNES, nonlinear, set, convergence, tolerances

    2949: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()

    2951: @*/
    2952: PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
    2953: {
    2956:   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
    2957:   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
    2959:   snes->lagjacobian = lag;
    2960:   return(0);
    2961: }

    2965: /*@
    2966:    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt

    2968:    Not Collective

    2970:    Input Parameter:
    2971: .  snes - the SNES context

    2973:    Output Parameter:
    2974: .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
    2975:          the Jacobian is built etc.

    2977:    Options Database Keys:
    2978: .    -snes_lag_jacobian <lag>

    2980:    Notes:
    2981:    The default is 1
    2982:    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

    2984:    Level: intermediate

    2986: .keywords: SNES, nonlinear, set, convergence, tolerances

    2988: .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()

    2990: @*/
    2991: PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
    2992: {
    2995:   *lag = snes->lagjacobian;
    2996:   return(0);
    2997: }

    3001: /*@
    3002:    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves

    3004:    Logically collective on SNES

    3006:    Input Parameter:
    3007: +  snes - the SNES context
    3008: -   flg - jacobian lagging persists if true

    3010:    Options Database Keys:
    3011: .    -snes_lag_jacobian_persists <flg>

    3013:    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
    3014:    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
    3015:    timesteps may present huge efficiency gains.

    3017:    Level: developer

    3019: .keywords: SNES, nonlinear, lag

    3021: .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()

    3023: @*/
    3024: PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
    3025: {
    3029:   snes->lagjac_persist = flg;
    3030:   return(0);
    3031: }

    3035: /*@
    3036:    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves

    3038:    Logically Collective on SNES

    3040:    Input Parameter:
    3041: +  snes - the SNES context
    3042: -   flg - preconditioner lagging persists if true

    3044:    Options Database Keys:
    3045: .    -snes_lag_jacobian_persists <flg>

    3047:    Notes: This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
    3048:    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
    3049:    several timesteps may present huge efficiency gains.

    3051:    Level: developer

    3053: .keywords: SNES, nonlinear, lag

    3055: .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()

    3057: @*/
    3058: PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
    3059: {
    3063:   snes->lagpre_persist = flg;
    3064:   return(0);
    3065: }

    3069: /*@
    3070:    SNESSetTolerances - Sets various parameters used in convergence tests.

    3072:    Logically Collective on SNES

    3074:    Input Parameters:
    3075: +  snes - the SNES context
    3076: .  abstol - absolute convergence tolerance
    3077: .  rtol - relative convergence tolerance
    3078: .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
    3079: .  maxit - maximum number of iterations
    3080: -  maxf - maximum number of function evaluations

    3082:    Options Database Keys:
    3083: +    -snes_atol <abstol> - Sets abstol
    3084: .    -snes_rtol <rtol> - Sets rtol
    3085: .    -snes_stol <stol> - Sets stol
    3086: .    -snes_max_it <maxit> - Sets maxit
    3087: -    -snes_max_funcs <maxf> - Sets maxf

    3089:    Notes:
    3090:    The default maximum number of iterations is 50.
    3091:    The default maximum number of function evaluations is 1000.

    3093:    Level: intermediate

    3095: .keywords: SNES, nonlinear, set, convergence, tolerances

    3097: .seealso: SNESSetTrustRegionTolerance()
    3098: @*/
    3099: PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
    3100: {

    3109:   if (abstol != PETSC_DEFAULT) {
    3110:     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol);
    3111:     snes->abstol = abstol;
    3112:   }
    3113:   if (rtol != PETSC_DEFAULT) {
    3114:     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);
    3115:     snes->rtol = rtol;
    3116:   }
    3117:   if (stol != PETSC_DEFAULT) {
    3118:     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol);
    3119:     snes->stol = stol;
    3120:   }
    3121:   if (maxit != PETSC_DEFAULT) {
    3122:     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
    3123:     snes->max_its = maxit;
    3124:   }
    3125:   if (maxf != PETSC_DEFAULT) {
    3126:     if (maxf < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be non-negative",maxf);
    3127:     snes->max_funcs = maxf;
    3128:   }
    3129:   snes->tolerancesset = PETSC_TRUE;
    3130:   return(0);
    3131: }

    3135: /*@
    3136:    SNESGetTolerances - Gets various parameters used in convergence tests.

    3138:    Not Collective

    3140:    Input Parameters:
    3141: +  snes - the SNES context
    3142: .  atol - absolute convergence tolerance
    3143: .  rtol - relative convergence tolerance
    3144: .  stol -  convergence tolerance in terms of the norm
    3145:            of the change in the solution between steps
    3146: .  maxit - maximum number of iterations
    3147: -  maxf - maximum number of function evaluations

    3149:    Notes:
    3150:    The user can specify NULL for any parameter that is not needed.

    3152:    Level: intermediate

    3154: .keywords: SNES, nonlinear, get, convergence, tolerances

    3156: .seealso: SNESSetTolerances()
    3157: @*/
    3158: PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
    3159: {
    3162:   if (atol)  *atol  = snes->abstol;
    3163:   if (rtol)  *rtol  = snes->rtol;
    3164:   if (stol)  *stol  = snes->stol;
    3165:   if (maxit) *maxit = snes->max_its;
    3166:   if (maxf)  *maxf  = snes->max_funcs;
    3167:   return(0);
    3168: }

    3172: /*@
    3173:    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.

    3175:    Logically Collective on SNES

    3177:    Input Parameters:
    3178: +  snes - the SNES context
    3179: -  tol - tolerance

    3181:    Options Database Key:
    3182: .  -snes_trtol <tol> - Sets tol

    3184:    Level: intermediate

    3186: .keywords: SNES, nonlinear, set, trust region, tolerance

    3188: .seealso: SNESSetTolerances()
    3189: @*/
    3190: PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
    3191: {
    3195:   snes->deltatol = tol;
    3196:   return(0);
    3197: }

    3199: /*
    3200:    Duplicate the lg monitors for SNES from KSP; for some reason with
    3201:    dynamic libraries things don't work under Sun4 if we just use
    3202:    macros instead of functions
    3203: */
    3206: PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,PetscObject *objs)
    3207: {

    3212:   KSPMonitorLGResidualNorm((KSP)snes,it,norm,objs);
    3213:   return(0);
    3214: }

    3218: PetscErrorCode  SNESMonitorLGCreate(const char host[],const char label[],int x,int y,int m,int n,PetscObject **draw)
    3219: {

    3223:   KSPMonitorLGResidualNormCreate(host,label,x,y,m,n,draw);
    3224:   return(0);
    3225: }

    3229: PetscErrorCode  SNESMonitorLGDestroy(PetscObject **objs)
    3230: {

    3234:   KSPMonitorLGResidualNormDestroy(objs);
    3235:   return(0);
    3236: }

    3238: extern PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);
    3241: PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
    3242: {
    3243:   PetscDrawLG      lg;
    3244:   PetscErrorCode   ierr;
    3245:   PetscReal        x,y,per;
    3246:   PetscViewer      v = (PetscViewer)monctx;
    3247:   static PetscReal prev; /* should be in the context */
    3248:   PetscDraw        draw;

    3251:   PetscViewerDrawGetDrawLG(v,0,&lg);
    3252:   if (!n) {PetscDrawLGReset(lg);}
    3253:   PetscDrawLGGetDraw(lg,&draw);
    3254:   PetscDrawSetTitle(draw,"Residual norm");
    3255:   x    = (PetscReal)n;
    3256:   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
    3257:   else y = -15.0;
    3258:   PetscDrawLGAddPoint(lg,&x,&y);
    3259:   if (n < 20 || !(n % 5)) {
    3260:     PetscDrawLGDraw(lg);
    3261:   }

    3263:   PetscViewerDrawGetDrawLG(v,1,&lg);
    3264:   if (!n) {PetscDrawLGReset(lg);}
    3265:   PetscDrawLGGetDraw(lg,&draw);
    3266:   PetscDrawSetTitle(draw,"% elemts > .2*max elemt");
    3267:    SNESMonitorRange_Private(snes,n,&per);
    3268:   x    = (PetscReal)n;
    3269:   y    = 100.0*per;
    3270:   PetscDrawLGAddPoint(lg,&x,&y);
    3271:   if (n < 20 || !(n % 5)) {
    3272:     PetscDrawLGDraw(lg);
    3273:   }

    3275:   PetscViewerDrawGetDrawLG(v,2,&lg);
    3276:   if (!n) {prev = rnorm;PetscDrawLGReset(lg);}
    3277:   PetscDrawLGGetDraw(lg,&draw);
    3278:   PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");
    3279:   x    = (PetscReal)n;
    3280:   y    = (prev - rnorm)/prev;
    3281:   PetscDrawLGAddPoint(lg,&x,&y);
    3282:   if (n < 20 || !(n % 5)) {
    3283:     PetscDrawLGDraw(lg);
    3284:   }

    3286:   PetscViewerDrawGetDrawLG(v,3,&lg);
    3287:   if (!n) {PetscDrawLGReset(lg);}
    3288:   PetscDrawLGGetDraw(lg,&draw);
    3289:   PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");
    3290:   x    = (PetscReal)n;
    3291:   y    = (prev - rnorm)/(prev*per);
    3292:   if (n > 2) { /*skip initial crazy value */
    3293:     PetscDrawLGAddPoint(lg,&x,&y);
    3294:   }
    3295:   if (n < 20 || !(n % 5)) {
    3296:     PetscDrawLGDraw(lg);
    3297:   }
    3298:   prev = rnorm;
    3299:   return(0);
    3300: }

    3304: /*@
    3305:    SNESMonitor - runs the user provided monitor routines, if they exist

    3307:    Collective on SNES

    3309:    Input Parameters:
    3310: +  snes - nonlinear solver context obtained from SNESCreate()
    3311: .  iter - iteration number
    3312: -  rnorm - relative norm of the residual

    3314:    Notes:
    3315:    This routine is called by the SNES implementations.
    3316:    It does not typically need to be called by the user.

    3318:    Level: developer

    3320: .seealso: SNESMonitorSet()
    3321: @*/
    3322: PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
    3323: {
    3325:   PetscInt       i,n = snes->numbermonitors;

    3328:   VecLockPush(snes->vec_sol);
    3329:   for (i=0; i<n; i++) {
    3330:     (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);
    3331:   }
    3332:   VecLockPop(snes->vec_sol);
    3333:   return(0);
    3334: }

    3336: /* ------------ Routines to set performance monitoring options ----------- */

    3338: /*MC
    3339:     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver

    3341:      Synopsis:
    3342:      #include <petscsnes.h>
    3343: $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)

    3345: +    snes - the SNES context
    3346: .    its - iteration number
    3347: .    norm - 2-norm function value (may be estimated)
    3348: -    mctx - [optional] monitoring context

    3350:    Level: advanced

    3352: .seealso:   SNESMonitorSet(), SNESMonitorGet()
    3353: M*/

    3357: /*@C
    3358:    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
    3359:    iteration of the nonlinear solver to display the iteration's
    3360:    progress.

    3362:    Logically Collective on SNES

    3364:    Input Parameters:
    3365: +  snes - the SNES context
    3366: .  f - the monitor function, see SNESMonitorFunction for the calling sequence
    3367: .  mctx - [optional] user-defined context for private data for the
    3368:           monitor routine (use NULL if no context is desired)
    3369: -  monitordestroy - [optional] routine that frees monitor context
    3370:           (may be NULL)

    3372:    Options Database Keys:
    3373: +    -snes_monitor        - sets SNESMonitorDefault()
    3374: .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
    3375:                             uses SNESMonitorLGCreate()
    3376: -    -snes_monitor_cancel - cancels all monitors that have
    3377:                             been hardwired into a code by
    3378:                             calls to SNESMonitorSet(), but
    3379:                             does not cancel those set via
    3380:                             the options database.

    3382:    Notes:
    3383:    Several different monitoring routines may be set by calling
    3384:    SNESMonitorSet() multiple times; all will be called in the
    3385:    order in which they were set.

    3387:    Fortran notes: Only a single monitor function can be set for each SNES object

    3389:    Level: intermediate

    3391: .keywords: SNES, nonlinear, set, monitor

    3393: .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
    3394: @*/
    3395: PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
    3396: {
    3397:   PetscInt       i;

    3402:   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
    3403:   for (i=0; i<snes->numbermonitors;i++) {
    3404:     if (f == snes->monitor[i] && monitordestroy == snes->monitordestroy[i] && mctx == snes->monitorcontext[i]) {
    3405:       if (monitordestroy) {
    3406:         (*monitordestroy)(&mctx);
    3407:       }
    3408:       return(0);
    3409:     }
    3410:   }
    3411:   snes->monitor[snes->numbermonitors]          = f;
    3412:   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
    3413:   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
    3414:   return(0);
    3415: }

    3419: /*@
    3420:    SNESMonitorCancel - Clears all the monitor functions for a SNES object.

    3422:    Logically Collective on SNES

    3424:    Input Parameters:
    3425: .  snes - the SNES context

    3427:    Options Database Key:
    3428: .  -snes_monitor_cancel - cancels all monitors that have been hardwired
    3429:     into a code by calls to SNESMonitorSet(), but does not cancel those
    3430:     set via the options database

    3432:    Notes:
    3433:    There is no way to clear one specific monitor from a SNES object.

    3435:    Level: intermediate

    3437: .keywords: SNES, nonlinear, set, monitor

    3439: .seealso: SNESMonitorDefault(), SNESMonitorSet()
    3440: @*/
    3441: PetscErrorCode  SNESMonitorCancel(SNES snes)
    3442: {
    3444:   PetscInt       i;

    3448:   for (i=0; i<snes->numbermonitors; i++) {
    3449:     if (snes->monitordestroy[i]) {
    3450:       (*snes->monitordestroy[i])(&snes->monitorcontext[i]);
    3451:     }
    3452:   }
    3453:   snes->numbermonitors = 0;
    3454:   return(0);
    3455: }

    3457: /*MC
    3458:     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver

    3460:      Synopsis:
    3461:      #include <petscsnes.h>
    3462: $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)

    3464: +    snes - the SNES context
    3465: .    it - current iteration (0 is the first and is before any Newton step)
    3466: .    cctx - [optional] convergence context
    3467: .    reason - reason for convergence/divergence
    3468: .    xnorm - 2-norm of current iterate
    3469: .    gnorm - 2-norm of current step
    3470: -    f - 2-norm of function

    3472:    Level: intermediate

    3474: .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
    3475: M*/

    3479: /*@C
    3480:    SNESSetConvergenceTest - Sets the function that is to be used
    3481:    to test for convergence of the nonlinear iterative solution.

    3483:    Logically Collective on SNES

    3485:    Input Parameters:
    3486: +  snes - the SNES context
    3487: .  SNESConvergenceTestFunction - routine to test for convergence
    3488: .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
    3489: -  destroy - [optional] destructor for the context (may be NULL; NULL_FUNCTION in Fortran)

    3491:    Level: advanced

    3493: .keywords: SNES, nonlinear, set, convergence, test

    3495: .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
    3496: @*/
    3497: PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
    3498: {

    3503:   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
    3504:   if (snes->ops->convergeddestroy) {
    3505:     (*snes->ops->convergeddestroy)(snes->cnvP);
    3506:   }
    3507:   snes->ops->converged        = SNESConvergenceTestFunction;
    3508:   snes->ops->convergeddestroy = destroy;
    3509:   snes->cnvP                  = cctx;
    3510:   return(0);
    3511: }

    3515: /*@
    3516:    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.

    3518:    Not Collective

    3520:    Input Parameter:
    3521: .  snes - the SNES context

    3523:    Output Parameter:
    3524: .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
    3525:             manual pages for the individual convergence tests for complete lists

    3527:    Level: intermediate

    3529:    Notes: Can only be called after the call the SNESSolve() is complete.

    3531: .keywords: SNES, nonlinear, set, convergence, test

    3533: .seealso: SNESSetConvergenceTest(), SNESConvergedReason
    3534: @*/
    3535: PetscErrorCode  SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
    3536: {
    3540:   *reason = snes->reason;
    3541:   return(0);
    3542: }

    3546: /*@
    3547:    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.

    3549:    Logically Collective on SNES

    3551:    Input Parameters:
    3552: +  snes - iterative context obtained from SNESCreate()
    3553: .  a   - array to hold history, this array will contain the function norms computed at each step
    3554: .  its - integer array holds the number of linear iterations for each solve.
    3555: .  na  - size of a and its
    3556: -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
    3557:            else it continues storing new values for new nonlinear solves after the old ones

    3559:    Notes:
    3560:    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
    3561:    default array of length 10000 is allocated.

    3563:    This routine is useful, e.g., when running a code for purposes
    3564:    of accurate performance monitoring, when no I/O should be done
    3565:    during the section of code that is being timed.

    3567:    Level: intermediate

    3569: .keywords: SNES, set, convergence, history

    3571: .seealso: SNESGetConvergenceHistory()

    3573: @*/
    3574: PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
    3575: {

    3582:   if (!a) {
    3583:     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
    3584:     PetscCalloc1(na,&a);
    3585:     PetscCalloc1(na,&its);

    3587:     snes->conv_malloc = PETSC_TRUE;
    3588:   }
    3589:   snes->conv_hist       = a;
    3590:   snes->conv_hist_its   = its;
    3591:   snes->conv_hist_max   = na;
    3592:   snes->conv_hist_len   = 0;
    3593:   snes->conv_hist_reset = reset;
    3594:   return(0);
    3595: }

    3597: #if defined(PETSC_HAVE_MATLAB_ENGINE)
    3598: #include <engine.h>   /* MATLAB include file */
    3599: #include <mex.h>      /* MATLAB include file */

    3603: PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
    3604: {
    3605:   mxArray   *mat;
    3606:   PetscInt  i;
    3607:   PetscReal *ar;

    3610:   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
    3611:   ar  = (PetscReal*) mxGetData(mat);
    3612:   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
    3613:   PetscFunctionReturn(mat);
    3614: }
    3615: #endif

    3619: /*@C
    3620:    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.

    3622:    Not Collective

    3624:    Input Parameter:
    3625: .  snes - iterative context obtained from SNESCreate()

    3627:    Output Parameters:
    3628: .  a   - array to hold history
    3629: .  its - integer array holds the number of linear iterations (or
    3630:          negative if not converged) for each solve.
    3631: -  na  - size of a and its

    3633:    Notes:
    3634:     The calling sequence for this routine in Fortran is
    3635: $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)

    3637:    This routine is useful, e.g., when running a code for purposes
    3638:    of accurate performance monitoring, when no I/O should be done
    3639:    during the section of code that is being timed.

    3641:    Level: intermediate

    3643: .keywords: SNES, get, convergence, history

    3645: .seealso: SNESSetConvergencHistory()

    3647: @*/
    3648: PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
    3649: {
    3652:   if (a)   *a   = snes->conv_hist;
    3653:   if (its) *its = snes->conv_hist_its;
    3654:   if (na)  *na  = snes->conv_hist_len;
    3655:   return(0);
    3656: }

    3660: /*@C
    3661:   SNESSetUpdate - Sets the general-purpose update function called
    3662:   at the beginning of every iteration of the nonlinear solve. Specifically
    3663:   it is called just before the Jacobian is "evaluated".

    3665:   Logically Collective on SNES

    3667:   Input Parameters:
    3668: . snes - The nonlinear solver context
    3669: . func - The function

    3671:   Calling sequence of func:
    3672: . func (SNES snes, PetscInt step);

    3674: . step - The current step of the iteration

    3676:   Level: advanced

    3678:   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()
    3679:         This is not used by most users.

    3681: .keywords: SNES, update

    3683: .seealso SNESSetJacobian(), SNESSolve()
    3684: @*/
    3685: PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
    3686: {
    3689:   snes->ops->update = func;
    3690:   return(0);
    3691: }

    3695: /*
    3696:    SNESScaleStep_Private - Scales a step so that its length is less than the
    3697:    positive parameter delta.

    3699:     Input Parameters:
    3700: +   snes - the SNES context
    3701: .   y - approximate solution of linear system
    3702: .   fnorm - 2-norm of current function
    3703: -   delta - trust region size

    3705:     Output Parameters:
    3706: +   gpnorm - predicted function norm at the new point, assuming local
    3707:     linearization.  The value is zero if the step lies within the trust
    3708:     region, and exceeds zero otherwise.
    3709: -   ynorm - 2-norm of the step

    3711:     Note:
    3712:     For non-trust region methods such as SNESNEWTONLS, the parameter delta
    3713:     is set to be the maximum allowable step size.

    3715: .keywords: SNES, nonlinear, scale, step
    3716: */
    3717: PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
    3718: {
    3719:   PetscReal      nrm;
    3720:   PetscScalar    cnorm;

    3728:   VecNorm(y,NORM_2,&nrm);
    3729:   if (nrm > *delta) {
    3730:     nrm     = *delta/nrm;
    3731:     *gpnorm = (1.0 - nrm)*(*fnorm);
    3732:     cnorm   = nrm;
    3733:     VecScale(y,cnorm);
    3734:     *ynorm  = *delta;
    3735:   } else {
    3736:     *gpnorm = 0.0;
    3737:     *ynorm  = nrm;
    3738:   }
    3739:   return(0);
    3740: }

    3744: /*@
    3745:    SNESReasonView - Displays the reason a SNES solve converged or diverged to a viewer

    3747:    Collective on SNES

    3749:    Parameter:
    3750: +  snes - iterative context obtained from SNESCreate()
    3751: -  viewer - the viewer to display the reason

    3754:    Options Database Keys:
    3755: .  -snes_converged_reason - print reason for converged or diverged, also prints number of iterations

    3757:    Level: beginner

    3759: .keywords: SNES, solve, linear system

    3761: .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault()

    3763: @*/
    3764: PetscErrorCode  SNESReasonView(SNES snes,PetscViewer viewer)
    3765: {
    3767:   PetscBool      isAscii;

    3770:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isAscii);
    3771:   if (isAscii) {
    3772:     PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);
    3773:     if (snes->reason > 0) {
    3774:       if (((PetscObject) snes)->prefix) {
    3775:         PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve converged due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);
    3776:       } else {
    3777:         PetscViewerASCIIPrintf(viewer,"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);
    3778:       }
    3779:     } else {
    3780:       if (((PetscObject) snes)->prefix) {
    3781:         PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve did not converge due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);
    3782:       } else {
    3783:         PetscViewerASCIIPrintf(viewer,"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);
    3784:       }
    3785:     }
    3786:     PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);
    3787:   }
    3788:   return(0);
    3789: }

    3793: /*@C
    3794:   SNESReasonViewFromOptions - Processes command line options to determine if/how a SNESReason is to be viewed.

    3796:   Collective on SNES

    3798:   Input Parameters:
    3799: . snes   - the SNES object

    3801:   Level: intermediate

    3803: @*/
    3804: PetscErrorCode SNESReasonViewFromOptions(SNES snes)
    3805: {
    3806:   PetscErrorCode    ierr;
    3807:   PetscViewer       viewer;
    3808:   PetscBool         flg;
    3809:   static PetscBool  incall = PETSC_FALSE;
    3810:   PetscViewerFormat format;

    3813:   if (incall) return(0);
    3814:   incall = PETSC_TRUE;
    3815:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->prefix,"-snes_converged_reason",&viewer,&format,&flg);
    3816:   if (flg) {
    3817:     PetscViewerPushFormat(viewer,format);
    3818:     SNESReasonView(snes,viewer);
    3819:     PetscViewerPopFormat(viewer);
    3820:     PetscViewerDestroy(&viewer);
    3821:   }
    3822:   incall = PETSC_FALSE;
    3823:   return(0);
    3824: }

    3828: /*@C
    3829:    SNESSolve - Solves a nonlinear system F(x) = b.
    3830:    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().

    3832:    Collective on SNES

    3834:    Input Parameters:
    3835: +  snes - the SNES context
    3836: .  b - the constant part of the equation F(x) = b, or NULL to use zero.
    3837: -  x - the solution vector.

    3839:    Notes:
    3840:    The user should initialize the vector,x, with the initial guess
    3841:    for the nonlinear solve prior to calling SNESSolve.  In particular,
    3842:    to employ an initial guess of zero, the user should explicitly set
    3843:    this vector to zero by calling VecSet().

    3845:    Level: beginner

    3847: .keywords: SNES, nonlinear, solve

    3849: .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
    3850: @*/
    3851: PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
    3852: {
    3853:   PetscErrorCode    ierr;
    3854:   PetscBool         flg;
    3855:   PetscInt          grid;
    3856:   Vec               xcreated = NULL;
    3857:   DM                dm;

    3866:   if (!x) {
    3867:     SNESGetDM(snes,&dm);
    3868:     DMCreateGlobalVector(dm,&xcreated);
    3869:     x    = xcreated;
    3870:   }
    3871:   SNESViewFromOptions(snes,NULL,"-snes_view_pre");

    3873:   for (grid=0; grid<snes->gridsequence; grid++) {PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));}
    3874:   for (grid=0; grid<snes->gridsequence+1; grid++) {

    3876:     /* set solution vector */
    3877:     if (!grid) {PetscObjectReference((PetscObject)x);}
    3878:     VecDestroy(&snes->vec_sol);
    3879:     snes->vec_sol = x;
    3880:     SNESGetDM(snes,&dm);

    3882:     /* set affine vector if provided */
    3883:     if (b) { PetscObjectReference((PetscObject)b); }
    3884:     VecDestroy(&snes->vec_rhs);
    3885:     snes->vec_rhs = b;

    3887:     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
    3888:     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
    3889:     if (!snes->vec_sol_update /* && snes->vec_sol */) {
    3890:       VecDuplicate(snes->vec_sol,&snes->vec_sol_update);
    3891:       PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);
    3892:     }
    3893:     DMShellSetGlobalVector(dm,snes->vec_sol);
    3894:     SNESSetUp(snes);

    3896:     if (!grid) {
    3897:       if (snes->ops->computeinitialguess) {
    3898:         (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);
    3899:       }
    3900:     }

    3902:     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
    3903:     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}

    3905:     PetscLogEventBegin(SNES_Solve,snes,0,0,0);
    3906:     (*snes->ops->solve)(snes);
    3907:     PetscLogEventEnd(SNES_Solve,snes,0,0,0);
    3908:     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
    3909:     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */

    3911:     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
    3912:     if (snes->lagpre_persist) snes->pre_iter += snes->iter;

    3914:     flg  = PETSC_FALSE;
    3915:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-snes_test_local_min",&flg,NULL);
    3916:     if (flg && !PetscPreLoadingOn) { SNESTestLocalMin(snes); }
    3917:     SNESReasonViewFromOptions(snes);

    3919:     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
    3920:     if (grid <  snes->gridsequence) {
    3921:       DM  fine;
    3922:       Vec xnew;
    3923:       Mat interp;

    3925:       DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);
    3926:       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
    3927:       DMCreateInterpolation(snes->dm,fine,&interp,NULL);
    3928:       DMCreateGlobalVector(fine,&xnew);
    3929:       MatInterpolate(interp,x,xnew);
    3930:       DMInterpolate(snes->dm,interp,fine);
    3931:       MatDestroy(&interp);
    3932:       x    = xnew;

    3934:       SNESReset(snes);
    3935:       SNESSetDM(snes,fine);
    3936:       DMDestroy(&fine);
    3937:       PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));
    3938:     }
    3939:   }
    3940:   SNESViewFromOptions(snes,NULL,"-snes_view");
    3941:   VecViewFromOptions(snes->vec_sol,(PetscObject)snes,"-snes_view_solution");

    3943:   VecDestroy(&xcreated);
    3944:   PetscObjectSAWsBlock((PetscObject)snes);
    3945:   return(0);
    3946: }

    3948: /* --------- Internal routines for SNES Package --------- */

    3952: /*@C
    3953:    SNESSetType - Sets the method for the nonlinear solver.

    3955:    Collective on SNES

    3957:    Input Parameters:
    3958: +  snes - the SNES context
    3959: -  type - a known method

    3961:    Options Database Key:
    3962: .  -snes_type <type> - Sets the method; use -help for a list
    3963:    of available methods (for instance, newtonls or newtontr)

    3965:    Notes:
    3966:    See "petsc/include/petscsnes.h" for available methods (for instance)
    3967: +    SNESNEWTONLS - Newton's method with line search
    3968:      (systems of nonlinear equations)
    3969: .    SNESNEWTONTR - Newton's method with trust region
    3970:      (systems of nonlinear equations)

    3972:   Normally, it is best to use the SNESSetFromOptions() command and then
    3973:   set the SNES solver type from the options database rather than by using
    3974:   this routine.  Using the options database provides the user with
    3975:   maximum flexibility in evaluating the many nonlinear solvers.
    3976:   The SNESSetType() routine is provided for those situations where it
    3977:   is necessary to set the nonlinear solver independently of the command
    3978:   line or options database.  This might be the case, for example, when
    3979:   the choice of solver changes during the execution of the program,
    3980:   and the user's application is taking responsibility for choosing the
    3981:   appropriate method.

    3983:     Developer Notes: SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
    3984:     the constructor in that list and calls it to create the spexific object.

    3986:   Level: intermediate

    3988: .keywords: SNES, set, type

    3990: .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()

    3992: @*/
    3993: PetscErrorCode  SNESSetType(SNES snes,SNESType type)
    3994: {
    3995:   PetscErrorCode ierr,(*r)(SNES);
    3996:   PetscBool      match;

    4002:   PetscObjectTypeCompare((PetscObject)snes,type,&match);
    4003:   if (match) return(0);

    4005:    PetscFunctionListFind(SNESList,type,&r);
    4006:   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
    4007:   /* Destroy the previous private SNES context */
    4008:   if (snes->ops->destroy) {
    4009:     (*(snes)->ops->destroy)(snes);
    4010:     snes->ops->destroy = NULL;
    4011:   }
    4012:   /* Reinitialize function pointers in SNESOps structure */
    4013:   snes->ops->setup          = 0;
    4014:   snes->ops->solve          = 0;
    4015:   snes->ops->view           = 0;
    4016:   snes->ops->setfromoptions = 0;
    4017:   snes->ops->destroy        = 0;
    4018:   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
    4019:   snes->setupcalled = PETSC_FALSE;

    4021:   PetscObjectChangeTypeName((PetscObject)snes,type);
    4022:   (*r)(snes);
    4023:   return(0);
    4024: }

    4028: /*@C
    4029:    SNESGetType - Gets the SNES method type and name (as a string).

    4031:    Not Collective

    4033:    Input Parameter:
    4034: .  snes - nonlinear solver context

    4036:    Output Parameter:
    4037: .  type - SNES method (a character string)

    4039:    Level: intermediate

    4041: .keywords: SNES, nonlinear, get, type, name
    4042: @*/
    4043: PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
    4044: {
    4048:   *type = ((PetscObject)snes)->type_name;
    4049:   return(0);
    4050: }

    4054: /*@
    4055:   SNESSetSolution - Sets the solution vector for use by the SNES routines.

    4057:   Logically Collective on SNES and Vec

    4059:   Input Parameters:
    4060: + snes - the SNES context obtained from SNESCreate()
    4061: - u    - the solution vector

    4063:   Level: beginner

    4065: .keywords: SNES, set, solution
    4066: @*/
    4067: PetscErrorCode SNESSetSolution(SNES snes, Vec u)
    4068: {
    4069:   DM             dm;

    4075:   PetscObjectReference((PetscObject) u);
    4076:   VecDestroy(&snes->vec_sol);

    4078:   snes->vec_sol = u;

    4080:   SNESGetDM(snes, &dm);
    4081:   DMShellSetGlobalVector(dm, u);
    4082:   return(0);
    4083: }

    4087: /*@
    4088:    SNESGetSolution - Returns the vector where the approximate solution is
    4089:    stored. This is the fine grid solution when using SNESSetGridSequence().

    4091:    Not Collective, but Vec is parallel if SNES is parallel

    4093:    Input Parameter:
    4094: .  snes - the SNES context

    4096:    Output Parameter:
    4097: .  x - the solution

    4099:    Level: intermediate

    4101: .keywords: SNES, nonlinear, get, solution

    4103: .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
    4104: @*/
    4105: PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
    4106: {
    4110:   *x = snes->vec_sol;
    4111:   return(0);
    4112: }

    4116: /*@
    4117:    SNESGetSolutionUpdate - Returns the vector where the solution update is
    4118:    stored.

    4120:    Not Collective, but Vec is parallel if SNES is parallel

    4122:    Input Parameter:
    4123: .  snes - the SNES context

    4125:    Output Parameter:
    4126: .  x - the solution update

    4128:    Level: advanced

    4130: .keywords: SNES, nonlinear, get, solution, update

    4132: .seealso: SNESGetSolution(), SNESGetFunction()
    4133: @*/
    4134: PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
    4135: {
    4139:   *x = snes->vec_sol_update;
    4140:   return(0);
    4141: }

    4145: /*@C
    4146:    SNESGetFunction - Returns the vector where the function is stored.

    4148:    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.

    4150:    Input Parameter:
    4151: .  snes - the SNES context

    4153:    Output Parameter:
    4154: +  r - the vector that is used to store residuals (or NULL if you don't want it)
    4155: .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
    4156: -  ctx - the function context (or NULL if you don't want it)

    4158:    Level: advanced

    4160: .keywords: SNES, nonlinear, get, function

    4162: .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
    4163: @*/
    4164: PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
    4165: {
    4167:   DM             dm;

    4171:   if (r) {
    4172:     if (!snes->vec_func) {
    4173:       if (snes->vec_rhs) {
    4174:         VecDuplicate(snes->vec_rhs,&snes->vec_func);
    4175:       } else if (snes->vec_sol) {
    4176:         VecDuplicate(snes->vec_sol,&snes->vec_func);
    4177:       } else if (snes->dm) {
    4178:         DMCreateGlobalVector(snes->dm,&snes->vec_func);
    4179:       }
    4180:     }
    4181:     *r = snes->vec_func;
    4182:   }
    4183:   SNESGetDM(snes,&dm);
    4184:   DMSNESGetFunction(dm,f,ctx);
    4185:   return(0);
    4186: }

    4188: /*@C
    4189:    SNESGetNGS - Returns the NGS function and context.

    4191:    Input Parameter:
    4192: .  snes - the SNES context

    4194:    Output Parameter:
    4195: +  f - the function (or NULL) see SNESNGSFunction for details
    4196: -  ctx    - the function context (or NULL)

    4198:    Level: advanced

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

    4202: .seealso: SNESSetNGS(), SNESGetFunction()
    4203: @*/

    4207: PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
    4208: {
    4210:   DM             dm;

    4214:   SNESGetDM(snes,&dm);
    4215:   DMSNESGetNGS(dm,f,ctx);
    4216:   return(0);
    4217: }

    4221: /*@C
    4222:    SNESSetOptionsPrefix - Sets the prefix used for searching for all
    4223:    SNES options in the database.

    4225:    Logically Collective on SNES

    4227:    Input Parameter:
    4228: +  snes - the SNES context
    4229: -  prefix - the prefix to prepend to all option names

    4231:    Notes:
    4232:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    4233:    The first character of all runtime options is AUTOMATICALLY the hyphen.

    4235:    Level: advanced

    4237: .keywords: SNES, set, options, prefix, database

    4239: .seealso: SNESSetFromOptions()
    4240: @*/
    4241: PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
    4242: {

    4247:   PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);
    4248:   if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
    4249:   if (snes->linesearch) {
    4250:     SNESGetLineSearch(snes,&snes->linesearch);
    4251:     PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);
    4252:   }
    4253:   KSPSetOptionsPrefix(snes->ksp,prefix);
    4254:   return(0);
    4255: }

    4259: /*@C
    4260:    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
    4261:    SNES options in the database.

    4263:    Logically Collective on SNES

    4265:    Input Parameters:
    4266: +  snes - the SNES context
    4267: -  prefix - the prefix to prepend to all option names

    4269:    Notes:
    4270:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    4271:    The first character of all runtime options is AUTOMATICALLY the hyphen.

    4273:    Level: advanced

    4275: .keywords: SNES, append, options, prefix, database

    4277: .seealso: SNESGetOptionsPrefix()
    4278: @*/
    4279: PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
    4280: {

    4285:   PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);
    4286:   if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
    4287:   if (snes->linesearch) {
    4288:     SNESGetLineSearch(snes,&snes->linesearch);
    4289:     PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);
    4290:   }
    4291:   KSPAppendOptionsPrefix(snes->ksp,prefix);
    4292:   return(0);
    4293: }

    4297: /*@C
    4298:    SNESGetOptionsPrefix - Sets the prefix used for searching for all
    4299:    SNES options in the database.

    4301:    Not Collective

    4303:    Input Parameter:
    4304: .  snes - the SNES context

    4306:    Output Parameter:
    4307: .  prefix - pointer to the prefix string used

    4309:    Notes: On the fortran side, the user should pass in a string 'prefix' of
    4310:    sufficient length to hold the prefix.

    4312:    Level: advanced

    4314: .keywords: SNES, get, options, prefix, database

    4316: .seealso: SNESAppendOptionsPrefix()
    4317: @*/
    4318: PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
    4319: {

    4324:   PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);
    4325:   return(0);
    4326: }

    4331: /*@C
    4332:   SNESRegister - Adds a method to the nonlinear solver package.

    4334:    Not collective

    4336:    Input Parameters:
    4337: +  name_solver - name of a new user-defined solver
    4338: -  routine_create - routine to create method context

    4340:    Notes:
    4341:    SNESRegister() may be called multiple times to add several user-defined solvers.

    4343:    Sample usage:
    4344: .vb
    4345:    SNESRegister("my_solver",MySolverCreate);
    4346: .ve

    4348:    Then, your solver can be chosen with the procedural interface via
    4349: $     SNESSetType(snes,"my_solver")
    4350:    or at runtime via the option
    4351: $     -snes_type my_solver

    4353:    Level: advanced

    4355:     Note: If your function is not being put into a shared library then use SNESRegister() instead

    4357: .keywords: SNES, nonlinear, register

    4359: .seealso: SNESRegisterAll(), SNESRegisterDestroy()

    4361:   Level: advanced
    4362: @*/
    4363: PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
    4364: {

    4368:   PetscFunctionListAdd(&SNESList,sname,function);
    4369:   return(0);
    4370: }

    4374: PetscErrorCode  SNESTestLocalMin(SNES snes)
    4375: {
    4377:   PetscInt       N,i,j;
    4378:   Vec            u,uh,fh;
    4379:   PetscScalar    value;
    4380:   PetscReal      norm;

    4383:   SNESGetSolution(snes,&u);
    4384:   VecDuplicate(u,&uh);
    4385:   VecDuplicate(u,&fh);

    4387:   /* currently only works for sequential */
    4388:   PetscPrintf(PETSC_COMM_WORLD,"Testing FormFunction() for local min\n");
    4389:   VecGetSize(u,&N);
    4390:   for (i=0; i<N; i++) {
    4391:     VecCopy(u,uh);
    4392:     PetscPrintf(PETSC_COMM_WORLD,"i = %D\n",i);
    4393:     for (j=-10; j<11; j++) {
    4394:       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
    4395:       VecSetValue(uh,i,value,ADD_VALUES);
    4396:       SNESComputeFunction(snes,uh,fh);
    4397:       VecNorm(fh,NORM_2,&norm);
    4398:       PetscPrintf(PETSC_COMM_WORLD,"       j norm %D %18.16e\n",j,norm);
    4399:       value = -value;
    4400:       VecSetValue(uh,i,value,ADD_VALUES);
    4401:     }
    4402:   }
    4403:   VecDestroy(&uh);
    4404:   VecDestroy(&fh);
    4405:   return(0);
    4406: }

    4410: /*@
    4411:    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
    4412:    computing relative tolerance for linear solvers within an inexact
    4413:    Newton method.

    4415:    Logically Collective on SNES

    4417:    Input Parameters:
    4418: +  snes - SNES context
    4419: -  flag - PETSC_TRUE or PETSC_FALSE

    4421:     Options Database:
    4422: +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
    4423: .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
    4424: .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
    4425: .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
    4426: .  -snes_ksp_ew_gamma <gamma> - Sets gamma
    4427: .  -snes_ksp_ew_alpha <alpha> - Sets alpha
    4428: .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
    4429: -  -snes_ksp_ew_threshold <threshold> - Sets threshold

    4431:    Notes:
    4432:    Currently, the default is to use a constant relative tolerance for
    4433:    the inner linear solvers.  Alternatively, one can use the
    4434:    Eisenstat-Walker method, where the relative convergence tolerance
    4435:    is reset at each Newton iteration according progress of the nonlinear
    4436:    solver.

    4438:    Level: advanced

    4440:    Reference:
    4441:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
    4442:    inexact Newton method", SISC 17 (1), pp.16-32, 1996.

    4444: .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton

    4446: .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
    4447: @*/
    4448: PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
    4449: {
    4453:   snes->ksp_ewconv = flag;
    4454:   return(0);
    4455: }

    4459: /*@
    4460:    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
    4461:    for computing relative tolerance for linear solvers within an
    4462:    inexact Newton method.

    4464:    Not Collective

    4466:    Input Parameter:
    4467: .  snes - SNES context

    4469:    Output Parameter:
    4470: .  flag - PETSC_TRUE or PETSC_FALSE

    4472:    Notes:
    4473:    Currently, the default is to use a constant relative tolerance for
    4474:    the inner linear solvers.  Alternatively, one can use the
    4475:    Eisenstat-Walker method, where the relative convergence tolerance
    4476:    is reset at each Newton iteration according progress of the nonlinear
    4477:    solver.

    4479:    Level: advanced

    4481:    Reference:
    4482:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
    4483:    inexact Newton method", SISC 17 (1), pp.16-32, 1996.

    4485: .keywords: SNES, KSP, Eisenstat, Walker, convergence, test, inexact, Newton

    4487: .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
    4488: @*/
    4489: PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
    4490: {
    4494:   *flag = snes->ksp_ewconv;
    4495:   return(0);
    4496: }

    4500: /*@
    4501:    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
    4502:    convergence criteria for the linear solvers within an inexact
    4503:    Newton method.

    4505:    Logically Collective on SNES

    4507:    Input Parameters:
    4508: +    snes - SNES context
    4509: .    version - version 1, 2 (default is 2) or 3
    4510: .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
    4511: .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
    4512: .    gamma - multiplicative factor for version 2 rtol computation
    4513:              (0 <= gamma2 <= 1)
    4514: .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
    4515: .    alpha2 - power for safeguard
    4516: -    threshold - threshold for imposing safeguard (0 < threshold < 1)

    4518:    Note:
    4519:    Version 3 was contributed by Luis Chacon, June 2006.

    4521:    Use PETSC_DEFAULT to retain the default for any of the parameters.

    4523:    Level: advanced

    4525:    Reference:
    4526:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
    4527:    inexact Newton method", Utah State University Math. Stat. Dept. Res.
    4528:    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.

    4530: .keywords: SNES, KSP, Eisenstat, Walker, set, parameters

    4532: .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
    4533: @*/
    4534: PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
    4535: {
    4536:   SNESKSPEW *kctx;

    4540:   kctx = (SNESKSPEW*)snes->kspconvctx;
    4541:   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");

    4550:   if (version != PETSC_DEFAULT)   kctx->version   = version;
    4551:   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
    4552:   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
    4553:   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
    4554:   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
    4555:   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
    4556:   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;

    4558:   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);
    4559:   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);
    4560:   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);
    4561:   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);
    4562:   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);
    4563:   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);
    4564:   return(0);
    4565: }

    4569: /*@
    4570:    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
    4571:    convergence criteria for the linear solvers within an inexact
    4572:    Newton method.

    4574:    Not Collective

    4576:    Input Parameters:
    4577:      snes - SNES context

    4579:    Output Parameters:
    4580: +    version - version 1, 2 (default is 2) or 3
    4581: .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
    4582: .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
    4583: .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
    4584: .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
    4585: .    alpha2 - power for safeguard
    4586: -    threshold - threshold for imposing safeguard (0 < threshold < 1)

    4588:    Level: advanced

    4590: .keywords: SNES, KSP, Eisenstat, Walker, get, parameters

    4592: .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
    4593: @*/
    4594: PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
    4595: {
    4596:   SNESKSPEW *kctx;

    4600:   kctx = (SNESKSPEW*)snes->kspconvctx;
    4601:   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
    4602:   if (version)   *version   = kctx->version;
    4603:   if (rtol_0)    *rtol_0    = kctx->rtol_0;
    4604:   if (rtol_max)  *rtol_max  = kctx->rtol_max;
    4605:   if (gamma)     *gamma     = kctx->gamma;
    4606:   if (alpha)     *alpha     = kctx->alpha;
    4607:   if (alpha2)    *alpha2    = kctx->alpha2;
    4608:   if (threshold) *threshold = kctx->threshold;
    4609:   return(0);
    4610: }

    4614:  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
    4615: {
    4617:   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
    4618:   PetscReal      rtol  = PETSC_DEFAULT,stol;

    4621:   if (!snes->ksp_ewconv) return(0);
    4622:   if (!snes->iter) {
    4623:     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
    4624:     VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);
    4625:   }
    4626:   else {
    4627:     if (kctx->version == 1) {
    4628:       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
    4629:       if (rtol < 0.0) rtol = -rtol;
    4630:       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
    4631:       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
    4632:     } else if (kctx->version == 2) {
    4633:       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
    4634:       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
    4635:       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
    4636:     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
    4637:       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
    4638:       /* safeguard: avoid sharp decrease of rtol */
    4639:       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
    4640:       stol = PetscMax(rtol,stol);
    4641:       rtol = PetscMin(kctx->rtol_0,stol);
    4642:       /* safeguard: avoid oversolving */
    4643:       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
    4644:       stol = PetscMax(rtol,stol);
    4645:       rtol = PetscMin(kctx->rtol_0,stol);
    4646:     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
    4647:   }
    4648:   /* safeguard: avoid rtol greater than one */
    4649:   rtol = PetscMin(rtol,kctx->rtol_max);
    4650:   KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);
    4651:   PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);
    4652:   return(0);
    4653: }

    4657: PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
    4658: {
    4660:   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
    4661:   PCSide         pcside;
    4662:   Vec            lres;

    4665:   if (!snes->ksp_ewconv) return(0);
    4666:   KSPGetTolerances(ksp,&kctx->rtol_last,0,0,0);
    4667:   kctx->norm_last = snes->norm;
    4668:   if (kctx->version == 1) {
    4669:     PC        pc;
    4670:     PetscBool isNone;

    4672:     KSPGetPC(ksp, &pc);
    4673:     PetscObjectTypeCompare((PetscObject) pc, PCNONE, &isNone);
    4674:     KSPGetPCSide(ksp,&pcside);
    4675:      if (pcside == PC_RIGHT || isNone) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
    4676:       /* KSP residual is true linear residual */
    4677:       KSPGetResidualNorm(ksp,&kctx->lresid_last);
    4678:     } else {
    4679:       /* KSP residual is preconditioned residual */
    4680:       /* compute true linear residual norm */
    4681:       VecDuplicate(b,&lres);
    4682:       MatMult(snes->jacobian,x,lres);
    4683:       VecAYPX(lres,-1.0,b);
    4684:       VecNorm(lres,NORM_2,&kctx->lresid_last);
    4685:       VecDestroy(&lres);
    4686:     }
    4687:   }
    4688:   return(0);
    4689: }

    4693: /*@
    4694:    SNESGetKSP - Returns the KSP context for a SNES solver.

    4696:    Not Collective, but if SNES object is parallel, then KSP object is parallel

    4698:    Input Parameter:
    4699: .  snes - the SNES context

    4701:    Output Parameter:
    4702: .  ksp - the KSP context

    4704:    Notes:
    4705:    The user can then directly manipulate the KSP context to set various
    4706:    options, etc.  Likewise, the user can then extract and manipulate the
    4707:    PC contexts as well.

    4709:    Level: beginner

    4711: .keywords: SNES, nonlinear, get, KSP, context

    4713: .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
    4714: @*/
    4715: PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
    4716: {

    4723:   if (!snes->ksp) {
    4724:     PetscBool monitor = PETSC_FALSE;

    4726:     KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);
    4727:     PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);
    4728:     PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);

    4730:     KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);
    4731:     KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);

    4733:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-ksp_monitor_snes",&monitor,NULL);
    4734:     if (monitor) {
    4735:       KSPMonitorSet(snes->ksp,KSPMonitorSNES,snes,NULL);
    4736:     }
    4737:     monitor = PETSC_FALSE;
    4738:     PetscOptionsGetBool(((PetscObject)snes)->prefix,"-ksp_monitor_snes_lg",&monitor,NULL);
    4739:     if (monitor) {
    4740:       PetscObject *objs;
    4741:       KSPMonitorSNESLGResidualNormCreate(0,0,PETSC_DECIDE,PETSC_DECIDE,600,600,&objs);
    4742:       objs[0] = (PetscObject) snes;
    4743:       KSPMonitorSet(snes->ksp,(PetscErrorCode (*)(KSP,PetscInt,PetscReal,void*))KSPMonitorSNESLGResidualNorm,objs,(PetscErrorCode (*)(void**))KSPMonitorSNESLGResidualNormDestroy);
    4744:     }
    4745:   }
    4746:   *ksp = snes->ksp;
    4747:   return(0);
    4748: }

    4751: #include <petsc/private/dmimpl.h>
    4754: /*@
    4755:    SNESSetDM - Sets the DM that may be used by some preconditioners

    4757:    Logically Collective on SNES

    4759:    Input Parameters:
    4760: +  snes - the preconditioner context
    4761: -  dm - the dm

    4763:    Level: intermediate

    4765: .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
    4766: @*/
    4767: PetscErrorCode  SNESSetDM(SNES snes,DM dm)
    4768: {
    4770:   KSP            ksp;
    4771:   DMSNES         sdm;

    4775:   if (dm) {PetscObjectReference((PetscObject)dm);}
    4776:   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
    4777:     if (snes->dm->dmsnes && snes->dmAuto && !dm->dmsnes) {
    4778:       DMCopyDMSNES(snes->dm,dm);
    4779:       DMGetDMSNES(snes->dm,&sdm);
    4780:       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
    4781:     }
    4782:     DMDestroy(&snes->dm);
    4783:   }
    4784:   snes->dm     = dm;
    4785:   snes->dmAuto = PETSC_FALSE;

    4787:   SNESGetKSP(snes,&ksp);
    4788:   KSPSetDM(ksp,dm);
    4789:   KSPSetDMActive(ksp,PETSC_FALSE);
    4790:   if (snes->pc) {
    4791:     SNESSetDM(snes->pc, snes->dm);
    4792:     SNESSetNPCSide(snes,snes->pcside);
    4793:   }
    4794:   return(0);
    4795: }

    4799: /*@
    4800:    SNESGetDM - Gets the DM that may be used by some preconditioners

    4802:    Not Collective but DM obtained is parallel on SNES

    4804:    Input Parameter:
    4805: . snes - the preconditioner context

    4807:    Output Parameter:
    4808: .  dm - the dm

    4810:    Level: intermediate

    4812: .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
    4813: @*/
    4814: PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
    4815: {

    4820:   if (!snes->dm) {
    4821:     DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);
    4822:     snes->dmAuto = PETSC_TRUE;
    4823:   }
    4824:   *dm = snes->dm;
    4825:   return(0);
    4826: }

    4830: /*@
    4831:   SNESSetNPC - Sets the nonlinear preconditioner to be used.

    4833:   Collective on SNES

    4835:   Input Parameters:
    4836: + snes - iterative context obtained from SNESCreate()
    4837: - pc   - the preconditioner object

    4839:   Notes:
    4840:   Use SNESGetNPC() to retrieve the preconditioner context (for example,
    4841:   to configure it using the API).

    4843:   Level: developer

    4845: .keywords: SNES, set, precondition
    4846: .seealso: SNESGetNPC(), SNESHasNPC()
    4847: @*/
    4848: PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
    4849: {

    4856:   PetscObjectReference((PetscObject) pc);
    4857:   SNESDestroy(&snes->pc);
    4858:   snes->pc = pc;
    4859:   PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->pc);
    4860:   return(0);
    4861: }

    4865: /*@
    4866:   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.

    4868:   Not Collective

    4870:   Input Parameter:
    4871: . snes - iterative context obtained from SNESCreate()

    4873:   Output Parameter:
    4874: . pc - preconditioner context

    4876:   Notes: If a SNES was previously set with SNESSetNPC() then that SNES is returned.

    4878:   Level: developer

    4880: .keywords: SNES, get, preconditioner
    4881: .seealso: SNESSetNPC(), SNESHasNPC()
    4882: @*/
    4883: PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
    4884: {
    4886:   const char     *optionsprefix;

    4891:   if (!snes->pc) {
    4892:     SNESCreate(PetscObjectComm((PetscObject)snes),&snes->pc);
    4893:     PetscObjectIncrementTabLevel((PetscObject)snes->pc,(PetscObject)snes,1);
    4894:     PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->pc);
    4895:     SNESGetOptionsPrefix(snes,&optionsprefix);
    4896:     SNESSetOptionsPrefix(snes->pc,optionsprefix);
    4897:     SNESAppendOptionsPrefix(snes->pc,"npc_");
    4898:     SNESSetCountersReset(snes->pc,PETSC_FALSE);
    4899:   }
    4900:   *pc = snes->pc;
    4901:   return(0);
    4902: }

    4906: /*@
    4907:   SNESHasNPC - Returns whether a nonlinear preconditioner exists

    4909:   Not Collective

    4911:   Input Parameter:
    4912: . snes - iterative context obtained from SNESCreate()

    4914:   Output Parameter:
    4915: . has_npc - whether the SNES has an NPC or not

    4917:   Level: developer

    4919: .keywords: SNES, has, preconditioner
    4920: .seealso: SNESSetNPC(), SNESGetNPC()
    4921: @*/
    4922: PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
    4923: {
    4926:   *has_npc = (PetscBool) (snes->pc != NULL);
    4927:   return(0);
    4928: }

    4932: /*@
    4933:     SNESSetNPCSide - Sets the preconditioning side.

    4935:     Logically Collective on SNES

    4937:     Input Parameter:
    4938: .   snes - iterative context obtained from SNESCreate()

    4940:     Output Parameter:
    4941: .   side - the preconditioning side, where side is one of
    4942: .vb
    4943:       PC_LEFT - left preconditioning (default)
    4944:       PC_RIGHT - right preconditioning
    4945: .ve

    4947:     Options Database Keys:
    4948: .   -snes_pc_side <right,left>

    4950:     Level: intermediate

    4952: .keywords: SNES, set, right, left, side, preconditioner, flag

    4954: .seealso: SNESGetNPCSide(), KSPSetPCSide()
    4955: @*/
    4956: PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
    4957: {
    4961:   snes->pcside = side;
    4962:   return(0);
    4963: }

    4967: /*@
    4968:     SNESGetNPCSide - Gets the preconditioning side.

    4970:     Not Collective

    4972:     Input Parameter:
    4973: .   snes - iterative context obtained from SNESCreate()

    4975:     Output Parameter:
    4976: .   side - the preconditioning side, where side is one of
    4977: .vb
    4978:       PC_LEFT - left preconditioning (default)
    4979:       PC_RIGHT - right preconditioning
    4980: .ve

    4982:     Level: intermediate

    4984: .keywords: SNES, get, right, left, side, preconditioner, flag

    4986: .seealso: SNESSetNPCSide(), KSPGetPCSide()
    4987: @*/
    4988: PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
    4989: {
    4993:   *side = snes->pcside;
    4994:   return(0);
    4995: }

    4999: /*@
    5000:   SNESSetLineSearch - Sets the linesearch on the SNES instance.

    5002:   Collective on SNES

    5004:   Input Parameters:
    5005: + snes - iterative context obtained from SNESCreate()
    5006: - linesearch   - the linesearch object

    5008:   Notes:
    5009:   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
    5010:   to configure it using the API).

    5012:   Level: developer

    5014: .keywords: SNES, set, linesearch
    5015: .seealso: SNESGetLineSearch()
    5016: @*/
    5017: PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
    5018: {

    5025:   PetscObjectReference((PetscObject) linesearch);
    5026:   SNESLineSearchDestroy(&snes->linesearch);

    5028:   snes->linesearch = linesearch;

    5030:   PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);
    5031:   return(0);
    5032: }

    5036: /*@
    5037:   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
    5038:   or creates a default line search instance associated with the SNES and returns it.

    5040:   Not Collective

    5042:   Input Parameter:
    5043: . snes - iterative context obtained from SNESCreate()

    5045:   Output Parameter:
    5046: . linesearch - linesearch context

    5048:   Level: beginner

    5050: .keywords: SNES, get, linesearch
    5051: .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
    5052: @*/
    5053: PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
    5054: {
    5056:   const char     *optionsprefix;

    5061:   if (!snes->linesearch) {
    5062:     SNESGetOptionsPrefix(snes, &optionsprefix);
    5063:     SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);
    5064:     SNESLineSearchSetSNES(snes->linesearch, snes);
    5065:     SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);
    5066:     PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);
    5067:     PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);
    5068:   }
    5069:   *linesearch = snes->linesearch;
    5070:   return(0);
    5071: }

    5073: #if defined(PETSC_HAVE_MATLAB_ENGINE)
    5074: #include <mex.h>

    5076: typedef struct {char *funcname; mxArray *ctx;} SNESMatlabContext;

    5080: /*
    5081:    SNESComputeFunction_Matlab - Calls the function that has been set with SNESSetFunctionMatlab().

    5083:    Collective on SNES

    5085:    Input Parameters:
    5086: +  snes - the SNES context
    5087: -  x - input vector

    5089:    Output Parameter:
    5090: .  y - function vector, as set by SNESSetFunction()

    5092:    Notes:
    5093:    SNESComputeFunction() is typically used within nonlinear solvers
    5094:    implementations, so most users would not generally call this routine
    5095:    themselves.

    5097:    Level: developer

    5099: .keywords: SNES, nonlinear, compute, function

    5101: .seealso: SNESSetFunction(), SNESGetFunction()
    5102: */
    5103: PetscErrorCode  SNESComputeFunction_Matlab(SNES snes,Vec x,Vec y, void *ctx)
    5104: {
    5105:   PetscErrorCode    ierr;
    5106:   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
    5107:   int               nlhs  = 1,nrhs = 5;
    5108:   mxArray           *plhs[1],*prhs[5];
    5109:   long long int     lx = 0,ly = 0,ls = 0;

    5118:   /* call Matlab function in ctx with arguments x and y */

    5120:   PetscMemcpy(&ls,&snes,sizeof(snes));
    5121:   PetscMemcpy(&lx,&x,sizeof(x));
    5122:   PetscMemcpy(&ly,&y,sizeof(x));
    5123:   prhs[0] = mxCreateDoubleScalar((double)ls);
    5124:   prhs[1] = mxCreateDoubleScalar((double)lx);
    5125:   prhs[2] = mxCreateDoubleScalar((double)ly);
    5126:   prhs[3] = mxCreateString(sctx->funcname);
    5127:   prhs[4] = sctx->ctx;
    5128:   mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeFunctionInternal");
    5129:   mxGetScalar(plhs[0]);
    5130:   mxDestroyArray(prhs[0]);
    5131:   mxDestroyArray(prhs[1]);
    5132:   mxDestroyArray(prhs[2]);
    5133:   mxDestroyArray(prhs[3]);
    5134:   mxDestroyArray(plhs[0]);
    5135:   return(0);
    5136: }

    5140: /*
    5141:    SNESSetFunctionMatlab - Sets the function evaluation routine and function
    5142:    vector for use by the SNES routines in solving systems of nonlinear
    5143:    equations from MATLAB. Here the function is a string containing the name of a MATLAB function

    5145:    Logically Collective on SNES

    5147:    Input Parameters:
    5148: +  snes - the SNES context
    5149: .  r - vector to store function value
    5150: -  f - function evaluation routine

    5152:    Notes:
    5153:    The Newton-like methods typically solve linear systems of the form
    5154: $      f'(x) x = -f(x),
    5155:    where f'(x) denotes the Jacobian matrix and f(x) is the function.

    5157:    Level: beginner

    5159:    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;

    5161: .keywords: SNES, nonlinear, set, function

    5163: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
    5164: */
    5165: PetscErrorCode  SNESSetFunctionMatlab(SNES snes,Vec r,const char *f,mxArray *ctx)
    5166: {
    5167:   PetscErrorCode    ierr;
    5168:   SNESMatlabContext *sctx;

    5171:   /* currently sctx is memory bleed */
    5172:   PetscNew(&sctx);
    5173:   PetscStrallocpy(f,&sctx->funcname);
    5174:   /*
    5175:      This should work, but it doesn't
    5176:   sctx->ctx = ctx;
    5177:   mexMakeArrayPersistent(sctx->ctx);
    5178:   */
    5179:   sctx->ctx = mxDuplicateArray(ctx);
    5180:   SNESSetFunction(snes,r,SNESComputeFunction_Matlab,sctx);
    5181:   return(0);
    5182: }

    5186: /*
    5187:    SNESComputeJacobian_Matlab - Calls the function that has been set with SNESSetJacobianMatlab().

    5189:    Collective on SNES

    5191:    Input Parameters:
    5192: +  snes - the SNES context
    5193: .  x - input vector
    5194: .  A, B - the matrices
    5195: -  ctx - user context

    5197:    Level: developer

    5199: .keywords: SNES, nonlinear, compute, function

    5201: .seealso: SNESSetFunction(), SNESGetFunction()
    5202: @*/
    5203: PetscErrorCode  SNESComputeJacobian_Matlab(SNES snes,Vec x,Mat A,Mat B,void *ctx)
    5204: {
    5205:   PetscErrorCode    ierr;
    5206:   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
    5207:   int               nlhs  = 2,nrhs = 6;
    5208:   mxArray           *plhs[2],*prhs[6];
    5209:   long long int     lx = 0,lA = 0,ls = 0, lB = 0;

    5215:   /* call Matlab function in ctx with arguments x and y */

    5217:   PetscMemcpy(&ls,&snes,sizeof(snes));
    5218:   PetscMemcpy(&lx,&x,sizeof(x));
    5219:   PetscMemcpy(&lA,A,sizeof(x));
    5220:   PetscMemcpy(&lB,B,sizeof(x));
    5221:   prhs[0] = mxCreateDoubleScalar((double)ls);
    5222:   prhs[1] = mxCreateDoubleScalar((double)lx);
    5223:   prhs[2] = mxCreateDoubleScalar((double)lA);
    5224:   prhs[3] = mxCreateDoubleScalar((double)lB);
    5225:   prhs[4] = mxCreateString(sctx->funcname);
    5226:   prhs[5] = sctx->ctx;
    5227:   mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESComputeJacobianInternal");
    5228:   mxGetScalar(plhs[0]);
    5229:   mxDestroyArray(prhs[0]);
    5230:   mxDestroyArray(prhs[1]);
    5231:   mxDestroyArray(prhs[2]);
    5232:   mxDestroyArray(prhs[3]);
    5233:   mxDestroyArray(prhs[4]);
    5234:   mxDestroyArray(plhs[0]);
    5235:   mxDestroyArray(plhs[1]);
    5236:   return(0);
    5237: }

    5241: /*
    5242:    SNESSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
    5243:    vector for use by the SNES routines in solving systems of nonlinear
    5244:    equations from MATLAB. Here the function is a string containing the name of a MATLAB function

    5246:    Logically Collective on SNES

    5248:    Input Parameters:
    5249: +  snes - the SNES context
    5250: .  A,B - Jacobian matrices
    5251: .  J - function evaluation routine
    5252: -  ctx - user context

    5254:    Level: developer

    5256:    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;

    5258: .keywords: SNES, nonlinear, set, function

    5260: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction(), J
    5261: */
    5262: PetscErrorCode  SNESSetJacobianMatlab(SNES snes,Mat A,Mat B,const char *J,mxArray *ctx)
    5263: {
    5264:   PetscErrorCode    ierr;
    5265:   SNESMatlabContext *sctx;

    5268:   /* currently sctx is memory bleed */
    5269:   PetscNew(&sctx);
    5270:   PetscStrallocpy(J,&sctx->funcname);
    5271:   /*
    5272:      This should work, but it doesn't
    5273:   sctx->ctx = ctx;
    5274:   mexMakeArrayPersistent(sctx->ctx);
    5275:   */
    5276:   sctx->ctx = mxDuplicateArray(ctx);
    5277:   SNESSetJacobian(snes,A,B,SNESComputeJacobian_Matlab,sctx);
    5278:   return(0);
    5279: }

    5283: /*
    5284:    SNESMonitor_Matlab - Calls the function that has been set with SNESMonitorSetMatlab().

    5286:    Collective on SNES

    5288: .seealso: SNESSetFunction(), SNESGetFunction()
    5289: @*/
    5290: PetscErrorCode  SNESMonitor_Matlab(SNES snes,PetscInt it, PetscReal fnorm, void *ctx)
    5291: {
    5292:   PetscErrorCode    ierr;
    5293:   SNESMatlabContext *sctx = (SNESMatlabContext*)ctx;
    5294:   int               nlhs  = 1,nrhs = 6;
    5295:   mxArray           *plhs[1],*prhs[6];
    5296:   long long int     lx = 0,ls = 0;
    5297:   Vec               x  = snes->vec_sol;

    5302:   PetscMemcpy(&ls,&snes,sizeof(snes));
    5303:   PetscMemcpy(&lx,&x,sizeof(x));
    5304:   prhs[0] = mxCreateDoubleScalar((double)ls);
    5305:   prhs[1] = mxCreateDoubleScalar((double)it);
    5306:   prhs[2] = mxCreateDoubleScalar((double)fnorm);
    5307:   prhs[3] = mxCreateDoubleScalar((double)lx);
    5308:   prhs[4] = mxCreateString(sctx->funcname);
    5309:   prhs[5] = sctx->ctx;
    5310:   mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscSNESMonitorInternal");
    5311:   mxGetScalar(plhs[0]);
    5312:   mxDestroyArray(prhs[0]);
    5313:   mxDestroyArray(prhs[1]);
    5314:   mxDestroyArray(prhs[2]);
    5315:   mxDestroyArray(prhs[3]);
    5316:   mxDestroyArray(prhs[4]);
    5317:   mxDestroyArray(plhs[0]);
    5318:   return(0);
    5319: }

    5323: /*
    5324:    SNESMonitorSetMatlab - Sets the monitor function from MATLAB

    5326:    Level: developer

    5328:    Developer Note:  This bleeds the allocated memory SNESMatlabContext *sctx;

    5330: .keywords: SNES, nonlinear, set, function

    5332: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
    5333: */
    5334: PetscErrorCode  SNESMonitorSetMatlab(SNES snes,const char *f,mxArray *ctx)
    5335: {
    5336:   PetscErrorCode    ierr;
    5337:   SNESMatlabContext *sctx;

    5340:   /* currently sctx is memory bleed */
    5341:   PetscNew(&sctx);
    5342:   PetscStrallocpy(f,&sctx->funcname);
    5343:   /*
    5344:      This should work, but it doesn't
    5345:   sctx->ctx = ctx;
    5346:   mexMakeArrayPersistent(sctx->ctx);
    5347:   */
    5348:   sctx->ctx = mxDuplicateArray(ctx);
    5349:   SNESMonitorSet(snes,SNESMonitor_Matlab,sctx,NULL);
    5350:   return(0);
    5351: }

    5353: #endif