Actual source code: itcreate.c
petsc-3.13.6 2020-09-29
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      2: /*
      3:      The basic KSP routines, Create, View etc. are here.
      4: */
      5:  #include <petsc/private/kspimpl.h>

      7: /* Logging support */
      8: PetscClassId  KSP_CLASSID;
      9: PetscClassId  DMKSP_CLASSID;
     10: PetscClassId  KSPGUESS_CLASSID;
     11: PetscLogEvent KSP_GMRESOrthogonalization, KSP_SetUp, KSP_Solve, KSP_SolveTranspose;

     13: /*
     14:    Contains the list of registered KSP routines
     15: */
     16: PetscFunctionList KSPList              = 0;
     17: PetscBool         KSPRegisterAllCalled = PETSC_FALSE;

     19: /*@C
     20:   KSPLoad - Loads a KSP that has been stored in binary  with KSPView().

     22:   Collective on viewer

     24:   Input Parameters:
     25: + newdm - the newly loaded KSP, this needs to have been created with KSPCreate() or
     26:            some related function before a call to KSPLoad().
     27: - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()

     29:    Level: intermediate

     31:   Notes:
     32:    The type is determined by the data in the file, any type set into the KSP before this call is ignored.

     34:   Notes for advanced users:
     35:   Most users should not need to know the details of the binary storage
     36:   format, since KSPLoad() and KSPView() completely hide these details.
     37:   But for anyone who's interested, the standard binary matrix storage
     38:   format is
     39: .vb
     40:      has not yet been determined
     41: .ve

     43: .seealso: PetscViewerBinaryOpen(), KSPView(), MatLoad(), VecLoad()
     44: @*/
     45: PetscErrorCode  KSPLoad(KSP newdm, PetscViewer viewer)
     46: {
     48:   PetscBool      isbinary;
     49:   PetscInt       classid;
     50:   char           type[256];
     51:   PC             pc;

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

     59:   PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);
     60:   if (classid != KSP_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)newdm),PETSC_ERR_ARG_WRONG,"Not KSP next in file");
     61:   PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);
     62:   KSPSetType(newdm, type);
     63:   if (newdm->ops->load) {
     64:     (*newdm->ops->load)(newdm,viewer);
     65:   }
     66:   KSPGetPC(newdm,&pc);
     67:   PCLoad(pc,viewer);
     68:   return(0);
     69: }

     71:  #include <petscdraw.h>
     72: #if defined(PETSC_HAVE_SAWS)
     73:  #include <petscviewersaws.h>
     74: #endif
     75: /*@C
     76:    KSPView - Prints the KSP data structure.

     78:    Collective on ksp

     80:    Input Parameters:
     81: +  ksp - the Krylov space context
     82: -  viewer - visualization context

     84:    Options Database Keys:
     85: .  -ksp_view - print the ksp data structure at the end of a KSPSolve call

     87:    Note:
     88:    The available visualization contexts include
     89: +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
     90: -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
     91:          output where only the first processor opens
     92:          the file.  All other processors send their
     93:          data to the first processor to print.

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

     98:    Level: beginner

    100: .seealso: PCView(), PetscViewerASCIIOpen()
    101: @*/
    102: PetscErrorCode  KSPView(KSP ksp,PetscViewer viewer)
    103: {
    105:   PetscBool      iascii,isbinary,isdraw,isstring;
    106: #if defined(PETSC_HAVE_SAWS)
    107:   PetscBool      issaws;
    108: #endif

    112:   if (!viewer) {
    113:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)ksp),&viewer);
    114:   }

    118:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
    119:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
    120:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
    121:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);
    122: #if defined(PETSC_HAVE_SAWS)
    123:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);
    124: #endif
    125:   if (iascii) {
    126:     PetscObjectPrintClassNamePrefixType((PetscObject)ksp,viewer);
    127:     if (ksp->ops->view) {
    128:       PetscViewerASCIIPushTab(viewer);
    129:       (*ksp->ops->view)(ksp,viewer);
    130:       PetscViewerASCIIPopTab(viewer);
    131:     }
    132:     if (ksp->guess_zero) {
    133:       PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, initial guess is zero\n",ksp->max_it);
    134:     } else {
    135:       PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, nonzero initial guess\n", ksp->max_it);
    136:     }
    137:     if (ksp->guess_knoll) {PetscViewerASCIIPrintf(viewer,"  using preconditioner applied to right hand side for initial guess\n");}
    138:     PetscViewerASCIIPrintf(viewer,"  tolerances:  relative=%g, absolute=%g, divergence=%g\n",(double)ksp->rtol,(double)ksp->abstol,(double)ksp->divtol);
    139:     if (ksp->pc_side == PC_RIGHT) {
    140:       PetscViewerASCIIPrintf(viewer,"  right preconditioning\n");
    141:     } else if (ksp->pc_side == PC_SYMMETRIC) {
    142:       PetscViewerASCIIPrintf(viewer,"  symmetric preconditioning\n");
    143:     } else {
    144:       PetscViewerASCIIPrintf(viewer,"  left preconditioning\n");
    145:     }
    146:     if (ksp->guess) {
    147:       PetscViewerASCIIPushTab(viewer);
    148:       KSPGuessView(ksp->guess,viewer);
    149:       PetscViewerASCIIPopTab(viewer);
    150:     }
    151:     if (ksp->dscale) {PetscViewerASCIIPrintf(viewer,"  diagonally scaled system\n");}
    152:     PetscViewerASCIIPrintf(viewer,"  using %s norm type for convergence test\n",KSPNormTypes[ksp->normtype]);
    153:   } else if (isbinary) {
    154:     PetscInt    classid = KSP_FILE_CLASSID;
    155:     MPI_Comm    comm;
    156:     PetscMPIInt rank;
    157:     char        type[256];

    159:     PetscObjectGetComm((PetscObject)ksp,&comm);
    160:     MPI_Comm_rank(comm,&rank);
    161:     if (!rank) {
    162:       PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT);
    163:       PetscStrncpy(type,((PetscObject)ksp)->type_name,256);
    164:       PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR);
    165:     }
    166:     if (ksp->ops->view) {
    167:       (*ksp->ops->view)(ksp,viewer);
    168:     }
    169:   } else if (isstring) {
    170:     const char *type;
    171:     KSPGetType(ksp,&type);
    172:     PetscViewerStringSPrintf(viewer," KSPType: %-7.7s",type);
    173:     if (ksp->ops->view) {(*ksp->ops->view)(ksp,viewer);}
    174:   } else if (isdraw) {
    175:     PetscDraw draw;
    176:     char      str[36];
    177:     PetscReal x,y,bottom,h;
    178:     PetscBool flg;

    180:     PetscViewerDrawGetDraw(viewer,0,&draw);
    181:     PetscDrawGetCurrentPoint(draw,&x,&y);
    182:     PetscObjectTypeCompare((PetscObject)ksp,KSPPREONLY,&flg);
    183:     if (!flg) {
    184:       PetscStrncpy(str,"KSP: ",sizeof(str));
    185:       PetscStrlcat(str,((PetscObject)ksp)->type_name,sizeof(str));
    186:       PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_RED,PETSC_DRAW_BLACK,str,NULL,&h);
    187:       bottom = y - h;
    188:     } else {
    189:       bottom = y;
    190:     }
    191:     PetscDrawPushCurrentPoint(draw,x,bottom);
    192: #if defined(PETSC_HAVE_SAWS)
    193:   } else if (issaws) {
    194:     PetscMPIInt rank;
    195:     const char  *name;

    197:     PetscObjectGetName((PetscObject)ksp,&name);
    198:     MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
    199:     if (!((PetscObject)ksp)->amsmem && !rank) {
    200:       char       dir[1024];

    202:       PetscObjectViewSAWs((PetscObject)ksp,viewer);
    203:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);
    204:       PetscStackCallSAWs(SAWs_Register,(dir,&ksp->its,1,SAWs_READ,SAWs_INT));
    205:       if (!ksp->res_hist) {
    206:         KSPSetResidualHistory(ksp,NULL,PETSC_DECIDE,PETSC_TRUE);
    207:       }
    208:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/res_hist",name);
    209:       PetscStackCallSAWs(SAWs_Register,(dir,ksp->res_hist,10,SAWs_READ,SAWs_DOUBLE));
    210:     }
    211: #endif
    212:   } else if (ksp->ops->view) {
    213:     (*ksp->ops->view)(ksp,viewer);
    214:   }
    215:   if (!ksp->skippcsetfromoptions) {
    216:     if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    217:     PCView(ksp->pc,viewer);
    218:   }
    219:   if (isdraw) {
    220:     PetscDraw draw;
    221:     PetscViewerDrawGetDraw(viewer,0,&draw);
    222:     PetscDrawPopCurrentPoint(draw);
    223:   }
    224:   return(0);
    225: }

    227: /*@C
    228:    KSPViewFromOptions - View from Options

    230:    Collective on KSP

    232:    Input Parameters:
    233: +  A - Krylov solver context
    234: .  obj - Optional object
    235: -  name - command line option

    237:    Level: intermediate
    238: .seealso:  KSP, KSPView, PetscObjectViewFromOptions(), KSPCreate()
    239: @*/
    240: PetscErrorCode  KSPViewFromOptions(KSP A,PetscObject obj,const char name[])
    241: {

    246:   PetscObjectViewFromOptions((PetscObject)A,obj,name);
    247:   return(0);
    248: }

    250: /*@
    251:    KSPSetNormType - Sets the norm that is used for convergence testing.

    253:    Logically Collective on ksp

    255:    Input Parameter:
    256: +  ksp - Krylov solver context
    257: -  normtype - one of
    258: $   KSP_NORM_NONE - skips computing the norm, this should generally only be used if you are using
    259: $                 the Krylov method as a smoother with a fixed small number of iterations.
    260: $                 Implicitly sets KSPConvergedSkip() as KSP convergence test.
    261: $                 Note that certain algorithms such as KSPGMRES ALWAYS require the norm calculation,
    262: $                 for these methods the norms are still computed, they are just not used in
    263: $                 the convergence test.
    264: $   KSP_NORM_PRECONDITIONED - the default for left preconditioned solves, uses the l2 norm
    265: $                 of the preconditioned residual P^{-1}(b - A x)
    266: $   KSP_NORM_UNPRECONDITIONED - uses the l2 norm of the true b - Ax residual.
    267: $   KSP_NORM_NATURAL - supported  by KSPCG, KSPCR, KSPCGNE, KSPCGS

    270:    Options Database Key:
    271: .   -ksp_norm_type <none,preconditioned,unpreconditioned,natural>

    273:    Notes:
    274:    Not all combinations of preconditioner side (see KSPSetPCSide()) and norm type are supported by all Krylov methods.
    275:    If only one is set, PETSc tries to automatically change the other to find a compatible pair.  If no such combination
    276:    is supported, PETSc will generate an error.

    278:    Developer Notes:
    279:    Supported combinations of norm and preconditioner side are set using KSPSetSupportedNorm().

    281:    Level: advanced

    283: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetCheckNormIteration(), KSPSetPCSide(), KSPGetPCSide(), KSPNormType
    284: @*/
    285: PetscErrorCode  KSPSetNormType(KSP ksp,KSPNormType normtype)
    286: {
    290:   ksp->normtype = ksp->normtype_set = normtype;
    291:   return(0);
    292: }

    294: /*@
    295:    KSPSetCheckNormIteration - Sets the first iteration at which the norm of the residual will be
    296:      computed and used in the convergence test.

    298:    Logically Collective on ksp

    300:    Input Parameter:
    301: +  ksp - Krylov solver context
    302: -  it  - use -1 to check at all iterations

    304:    Notes:
    305:    Currently only works with KSPCG, KSPBCGS and KSPIBCGS

    307:    Use KSPSetNormType(ksp,KSP_NORM_NONE) to never check the norm

    309:    On steps where the norm is not computed, the previous norm is still in the variable, so if you run with, for example,
    310:     -ksp_monitor the residual norm will appear to be unchanged for several iterations (though it is not really unchanged).
    311:    Level: advanced

    313: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType()
    314: @*/
    315: PetscErrorCode  KSPSetCheckNormIteration(KSP ksp,PetscInt it)
    316: {
    320:   ksp->chknorm = it;
    321:   return(0);
    322: }

    324: /*@
    325:    KSPSetLagNorm - Lags the residual norm calculation so that it is computed as part of the MPI_Allreduce() for
    326:    computing the inner products for the next iteration.  This can reduce communication costs at the expense of doing
    327:    one additional iteration.

    330:    Logically Collective on ksp

    332:    Input Parameter:
    333: +  ksp - Krylov solver context
    334: -  flg - PETSC_TRUE or PETSC_FALSE

    336:    Options Database Keys:
    337: .  -ksp_lag_norm - lag the calculated residual norm

    339:    Notes:
    340:    Currently only works with KSPIBCGS.

    342:    Use KSPSetNormType(ksp,KSP_NORM_NONE) to never check the norm

    344:    If you lag the norm and run with, for example, -ksp_monitor, the residual norm reported will be the lagged one.
    345:    Level: advanced

    347: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType(), KSPSetCheckNormIteration()
    348: @*/
    349: PetscErrorCode  KSPSetLagNorm(KSP ksp,PetscBool flg)
    350: {
    354:   ksp->lagnorm = flg;
    355:   return(0);
    356: }

    358: /*@
    359:    KSPSetSupportedNorm - Sets a norm and preconditioner side supported by a KSP

    361:    Logically Collective

    363:    Input Arguments:
    364: +  ksp - Krylov method
    365: .  normtype - supported norm type
    366: .  pcside - preconditioner side that can be used with this norm
    367: -  priority - positive integer preference for this combination; larger values have higher priority

    369:    Level: developer

    371:    Notes:
    372:    This function should be called from the implementation files KSPCreate_XXX() to declare
    373:    which norms and preconditioner sides are supported. Users should not need to call this
    374:    function.

    376: .seealso: KSPSetNormType(), KSPSetPCSide()
    377: @*/
    378: PetscErrorCode KSPSetSupportedNorm(KSP ksp,KSPNormType normtype,PCSide pcside,PetscInt priority)
    379: {

    383:   ksp->normsupporttable[normtype][pcside] = priority;
    384:   return(0);
    385: }

    387: PetscErrorCode KSPNormSupportTableReset_Private(KSP ksp)
    388: {

    392:   PetscMemzero(ksp->normsupporttable,sizeof(ksp->normsupporttable));
    393:   ksp->pc_side  = ksp->pc_side_set;
    394:   ksp->normtype = ksp->normtype_set;
    395:   return(0);
    396: }

    398: PetscErrorCode KSPSetUpNorms_Private(KSP ksp,PetscBool errorifnotsupported,KSPNormType *normtype,PCSide *pcside)
    399: {
    400:   PetscInt i,j,best,ibest = 0,jbest = 0;

    403:   best = 0;
    404:   for (i=0; i<KSP_NORM_MAX; i++) {
    405:     for (j=0; j<PC_SIDE_MAX; j++) {
    406:       if ((ksp->normtype == KSP_NORM_DEFAULT || ksp->normtype == i) && (ksp->pc_side == PC_SIDE_DEFAULT || ksp->pc_side == j) && (ksp->normsupporttable[i][j] > best)) {
    407:         best  = ksp->normsupporttable[i][j];
    408:         ibest = i;
    409:         jbest = j;
    410:       }
    411:     }
    412:   }
    413:   if (best < 1 && errorifnotsupported) {
    414:     if (ksp->normtype == KSP_NORM_DEFAULT && ksp->pc_side == PC_SIDE_DEFAULT) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_PLIB,"The %s KSP implementation did not call KSPSetSupportedNorm()",((PetscObject)ksp)->type_name);
    415:     if (ksp->normtype == KSP_NORM_DEFAULT) SETERRQ2(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"KSP %s does not support %s",((PetscObject)ksp)->type_name,PCSides[ksp->pc_side]);
    416:     if (ksp->pc_side == PC_SIDE_DEFAULT) SETERRQ2(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"KSP %s does not support %s",((PetscObject)ksp)->type_name,KSPNormTypes[ksp->normtype]);
    417:     SETERRQ3(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"KSP %s does not support %s with %s",((PetscObject)ksp)->type_name,KSPNormTypes[ksp->normtype],PCSides[ksp->pc_side]);
    418:   }
    419:   if (normtype) *normtype = (KSPNormType)ibest;
    420:   if (pcside)   *pcside   = (PCSide)jbest;
    421:   return(0);
    422: }

    424: /*@
    425:    KSPGetNormType - Gets the norm that is used for convergence testing.

    427:    Not Collective

    429:    Input Parameter:
    430: .  ksp - Krylov solver context

    432:    Output Parameter:
    433: .  normtype - norm that is used for convergence testing

    435:    Level: advanced

    437: .seealso: KSPNormType, KSPSetNormType(), KSPConvergedSkip()
    438: @*/
    439: PetscErrorCode  KSPGetNormType(KSP ksp, KSPNormType *normtype)
    440: {

    446:   KSPSetUpNorms_Private(ksp,PETSC_TRUE,&ksp->normtype,&ksp->pc_side);
    447:   *normtype = ksp->normtype;
    448:   return(0);
    449: }

    451: #if defined(PETSC_HAVE_SAWS)
    452:  #include <petscviewersaws.h>
    453: #endif

    455: /*@
    456:    KSPSetOperators - Sets the matrix associated with the linear system
    457:    and a (possibly) different one associated with the preconditioner.

    459:    Collective on ksp

    461:    Input Parameters:
    462: +  ksp - the KSP context
    463: .  Amat - the matrix that defines the linear system
    464: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

    466:    Notes:

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

    471:     All future calls to KSPSetOperators() must use the same size matrices!

    473:     Passing a NULL for Amat or Pmat removes the matrix that is currently used.

    475:     If you wish to replace either Amat or Pmat but leave the other one untouched then
    476:     first call KSPGetOperators() to get the one you wish to keep, call PetscObjectReference()
    477:     on it and then pass it back in in your call to KSPSetOperators().

    479:     Level: beginner

    481:    Alternative usage: If the operators have NOT been set with KSP/PCSetOperators() then the operators
    482:       are created in PC and returned to the user. In this case, if both operators
    483:       mat and pmat are requested, two DIFFERENT operators will be returned. If
    484:       only one is requested both operators in the PC will be the same (i.e. as
    485:       if one had called KSP/PCSetOperators() with the same argument for both Mats).
    486:       The user must set the sizes of the returned matrices and their type etc just
    487:       as if the user created them with MatCreate(). For example,

    489: $         KSP/PCGetOperators(ksp/pc,&mat,NULL); is equivalent to
    490: $           set size, type, etc of mat

    492: $         MatCreate(comm,&mat);
    493: $         KSP/PCSetOperators(ksp/pc,mat,mat);
    494: $         PetscObjectDereference((PetscObject)mat);
    495: $           set size, type, etc of mat

    497:      and

    499: $         KSP/PCGetOperators(ksp/pc,&mat,&pmat); is equivalent to
    500: $           set size, type, etc of mat and pmat

    502: $         MatCreate(comm,&mat);
    503: $         MatCreate(comm,&pmat);
    504: $         KSP/PCSetOperators(ksp/pc,mat,pmat);
    505: $         PetscObjectDereference((PetscObject)mat);
    506: $         PetscObjectDereference((PetscObject)pmat);
    507: $           set size, type, etc of mat and pmat

    509:     The rational for this support is so that when creating a TS, SNES, or KSP the hierarchy
    510:     of underlying objects (i.e. SNES, KSP, PC, Mat) and their livespans can be completely
    511:     managed by the top most level object (i.e. the TS, SNES, or KSP). Another way to look
    512:     at this is when you create a SNES you do not NEED to create a KSP and attach it to
    513:     the SNES object (the SNES object manages it for you). Similarly when you create a KSP
    514:     you do not need to attach a PC to it (the KSP object manages the PC object for you).
    515:     Thus, why should YOU have to create the Mat and attach it to the SNES/KSP/PC, when
    516:     it can be created for you?

    518: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPGetOperators(), KSPSetComputeOperators(), KSPSetComputeInitialGuess(), KSPSetComputeRHS()
    519: @*/
    520: PetscErrorCode  KSPSetOperators(KSP ksp,Mat Amat,Mat Pmat)
    521: {

    530:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    531:   PCSetOperators(ksp->pc,Amat,Pmat);
    532:   if (ksp->setupstage == KSP_SETUP_NEWRHS) ksp->setupstage = KSP_SETUP_NEWMATRIX;  /* so that next solve call will call PCSetUp() on new matrix */
    533:   return(0);
    534: }

    536: /*@
    537:    KSPGetOperators - Gets the matrix associated with the linear system
    538:    and a (possibly) different one associated with the preconditioner.

    540:    Collective on ksp

    542:    Input Parameter:
    543: .  ksp - the KSP context

    545:    Output Parameters:
    546: +  Amat - the matrix that defines the linear system
    547: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

    549:     Level: intermediate

    551:    Notes:
    552:     DOES NOT increase the reference counts of the matrix, so you should NOT destroy them.

    554: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPSetOperators(), KSPGetOperatorsSet()
    555: @*/
    556: PetscErrorCode  KSPGetOperators(KSP ksp,Mat *Amat,Mat *Pmat)
    557: {

    562:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    563:   PCGetOperators(ksp->pc,Amat,Pmat);
    564:   return(0);
    565: }

    567: /*@C
    568:    KSPGetOperatorsSet - Determines if the matrix associated with the linear system and
    569:    possibly a different one associated with the preconditioner have been set in the KSP.

    571:    Not collective, though the results on all processes should be the same

    573:    Input Parameter:
    574: .  pc - the KSP context

    576:    Output Parameters:
    577: +  mat - the matrix associated with the linear system was set
    578: -  pmat - matrix associated with the preconditioner was set, usually the same

    580:    Level: intermediate

    582: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperators(), PCGetOperatorsSet()
    583: @*/
    584: PetscErrorCode  KSPGetOperatorsSet(KSP ksp,PetscBool  *mat,PetscBool  *pmat)
    585: {

    590:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    591:   PCGetOperatorsSet(ksp->pc,mat,pmat);
    592:   return(0);
    593: }

    595: /*@C
    596:    KSPSetPreSolve - Sets a function that is called before every KSPSolve() is started

    598:    Logically Collective on ksp

    600:    Input Parameters:
    601: +   ksp - the solver object
    602: .   presolve - the function to call before the solve
    603: -   prectx - any context needed by the function

    605:    Calling sequence of presolve:
    606: $  func(KSP ksp,Vec rhs,Vec x,void *ctx)

    608: +  ksp - the KSP context
    609: .  rhs - the right-hand side vector
    610: .  x - the solution vector
    611: -  ctx - optional user-provided context

    613:    Level: developer

    615: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPostSolve()
    616: @*/
    617: PetscErrorCode  KSPSetPreSolve(KSP ksp,PetscErrorCode (*presolve)(KSP,Vec,Vec,void*),void *prectx)
    618: {
    621:   ksp->presolve = presolve;
    622:   ksp->prectx   = prectx;
    623:   return(0);
    624: }

    626: /*@C
    627:    KSPSetPostSolve - Sets a function that is called after every KSPSolve() completes (whether it converges or not)

    629:    Logically Collective on ksp

    631:    Input Parameters:
    632: +   ksp - the solver object
    633: .   postsolve - the function to call after the solve
    634: -   postctx - any context needed by the function

    636:    Level: developer

    638:    Calling sequence of postsolve:
    639: $  func(KSP ksp,Vec rhs,Vec x,void *ctx)

    641: +  ksp - the KSP context
    642: .  rhs - the right-hand side vector
    643: .  x - the solution vector
    644: -  ctx - optional user-provided context

    646: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPreSolve()
    647: @*/
    648: PetscErrorCode  KSPSetPostSolve(KSP ksp,PetscErrorCode (*postsolve)(KSP,Vec,Vec,void*),void *postctx)
    649: {
    652:   ksp->postsolve = postsolve;
    653:   ksp->postctx   = postctx;
    654:   return(0);
    655: }

    657: /*@
    658:    KSPCreate - Creates the default KSP context.

    660:    Collective

    662:    Input Parameter:
    663: .  comm - MPI communicator

    665:    Output Parameter:
    666: .  ksp - location to put the KSP context

    668:    Notes:
    669:    The default KSP type is GMRES with a restart of 30, using modified Gram-Schmidt
    670:    orthogonalization.

    672:    Level: beginner

    674: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP
    675: @*/
    676: PetscErrorCode  KSPCreate(MPI_Comm comm,KSP *inksp)
    677: {
    678:   KSP            ksp;
    680:   void           *ctx;

    684:   *inksp = 0;
    685:   KSPInitializePackage();

    687:   PetscHeaderCreate(ksp,KSP_CLASSID,"KSP","Krylov Method","KSP",comm,KSPDestroy,KSPView);

    689:   ksp->max_it  = 10000;
    690:   ksp->pc_side = ksp->pc_side_set = PC_SIDE_DEFAULT;
    691:   ksp->rtol    = 1.e-5;
    692: #if defined(PETSC_USE_REAL_SINGLE)
    693:   ksp->abstol  = 1.e-25;
    694: #else
    695:   ksp->abstol  = 1.e-50;
    696: #endif
    697:   ksp->divtol  = 1.e4;

    699:   ksp->chknorm        = -1;
    700:   ksp->normtype       = ksp->normtype_set = KSP_NORM_DEFAULT;
    701:   ksp->rnorm          = 0.0;
    702:   ksp->its            = 0;
    703:   ksp->guess_zero     = PETSC_TRUE;
    704:   ksp->calc_sings     = PETSC_FALSE;
    705:   ksp->res_hist       = NULL;
    706:   ksp->res_hist_alloc = NULL;
    707:   ksp->res_hist_len   = 0;
    708:   ksp->res_hist_max   = 0;
    709:   ksp->res_hist_reset = PETSC_TRUE;
    710:   ksp->numbermonitors = 0;
    711:   ksp->setfromoptionscalled = 0;

    713:   KSPConvergedDefaultCreate(&ctx);
    714:   KSPSetConvergenceTest(ksp,KSPConvergedDefault,ctx,KSPConvergedDefaultDestroy);
    715:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
    716:   ksp->ops->buildresidual = KSPBuildResidualDefault;

    718:   ksp->vec_sol    = 0;
    719:   ksp->vec_rhs    = 0;
    720:   ksp->pc         = 0;
    721:   ksp->data       = 0;
    722:   ksp->nwork      = 0;
    723:   ksp->work       = 0;
    724:   ksp->reason     = KSP_CONVERGED_ITERATING;
    725:   ksp->setupstage = KSP_SETUP_NEW;

    727:   KSPNormSupportTableReset_Private(ksp);

    729:   *inksp = ksp;
    730:   return(0);
    731: }

    733: /*@C
    734:    KSPSetType - Builds KSP for a particular solver.

    736:    Logically Collective on ksp

    738:    Input Parameters:
    739: +  ksp      - the Krylov space context
    740: -  type - a known method

    742:    Options Database Key:
    743: .  -ksp_type  <method> - Sets the method; use -help for a list
    744:     of available methods (for instance, cg or gmres)

    746:    Notes:
    747:    See "petsc/include/petscksp.h" for available methods (for instance,
    748:    KSPCG or KSPGMRES).

    750:   Normally, it is best to use the KSPSetFromOptions() command and
    751:   then set the KSP type from the options database rather than by using
    752:   this routine.  Using the options database provides the user with
    753:   maximum flexibility in evaluating the many different Krylov methods.
    754:   The KSPSetType() routine is provided for those situations where it
    755:   is necessary to set the iterative solver independently of the command
    756:   line or options database.  This might be the case, for example, when
    757:   the choice of iterative solver changes during the execution of the
    758:   program, and the user's Section 1.5 Writing Application Codes with PETSc is taking responsibility for
    759:   choosing the appropriate method.  In other words, this routine is
    760:   not for beginners.

    762:   Level: intermediate

    764:   Developer Note: KSPRegister() is used to add Krylov types to KSPList from which they
    765:   are accessed by KSPSetType().

    767: .seealso: PCSetType(), KSPType, KSPRegister(), KSPCreate()

    769: @*/
    770: PetscErrorCode  KSPSetType(KSP ksp, KSPType type)
    771: {
    772:   PetscErrorCode ierr,(*r)(KSP);
    773:   PetscBool      match;

    779:   PetscObjectTypeCompare((PetscObject)ksp,type,&match);
    780:   if (match) return(0);

    782:   PetscFunctionListFind(KSPList,type,&r);
    783:   if (!r) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested KSP type %s",type);
    784:   /* Destroy the previous private KSP context */
    785:   if (ksp->ops->destroy) {
    786:     (*ksp->ops->destroy)(ksp);
    787:     ksp->ops->destroy = NULL;
    788:   }
    789:   /* Reinitialize function pointers in KSPOps structure */
    790:   PetscMemzero(ksp->ops,sizeof(struct _KSPOps));
    791:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
    792:   ksp->ops->buildresidual = KSPBuildResidualDefault;
    793:   KSPNormSupportTableReset_Private(ksp);
    794:   /* Call the KSPCreate_XXX routine for this particular Krylov solver */
    795:   ksp->setupstage = KSP_SETUP_NEW;
    796:   PetscObjectChangeTypeName((PetscObject)ksp,type);
    797:   (*r)(ksp);
    798:   return(0);
    799: }

    801: /*@C
    802:    KSPGetType - Gets the KSP type as a string from the KSP object.

    804:    Not Collective

    806:    Input Parameter:
    807: .  ksp - Krylov context

    809:    Output Parameter:
    810: .  name - name of KSP method

    812:    Level: intermediate

    814: .seealso: KSPSetType()
    815: @*/
    816: PetscErrorCode  KSPGetType(KSP ksp,KSPType *type)
    817: {
    821:   *type = ((PetscObject)ksp)->type_name;
    822:   return(0);
    823: }

    825: /*@C
    826:   KSPRegister -  Adds a method to the Krylov subspace solver package.

    828:    Not Collective

    830:    Input Parameters:
    831: +  name_solver - name of a new user-defined solver
    832: -  routine_create - routine to create method context

    834:    Notes:
    835:    KSPRegister() may be called multiple times to add several user-defined solvers.

    837:    Sample usage:
    838: .vb
    839:    KSPRegister("my_solver",MySolverCreate);
    840: .ve

    842:    Then, your solver can be chosen with the procedural interface via
    843: $     KSPSetType(ksp,"my_solver")
    844:    or at runtime via the option
    845: $     -ksp_type my_solver

    847:    Level: advanced

    849: .seealso: KSPRegisterAll()
    850: @*/
    851: PetscErrorCode  KSPRegister(const char sname[],PetscErrorCode (*function)(KSP))
    852: {

    856:   KSPInitializePackage();
    857:   PetscFunctionListAdd(&KSPList,sname,function);
    858:   return(0);
    859: }