Date: 2015-10-02T22:20:34+00:00

Actual source code: itcreate.c
petsc-3.6.2 2015-10-02
Report Typos and Errors

      2: /*
      3:      The basic KSP routines, Create, View etc. are here.
      4: */
      5: #include <petsc/private/kspimpl.h>      /*I "petscksp.h" I*/

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

     12: /*
     13:    Contains the list of registered KSP routines
     14: */
     15: PetscFunctionList KSPList              = 0;
     16: PetscBool         KSPRegisterAllCalled = PETSC_FALSE;

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

     23:   Collective on PetscViewer

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

     30:    Level: intermediate

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

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

     44: .seealso: PetscViewerBinaryOpen(), KSPView(), MatLoad(), VecLoad()
     45: @*/
     46: PetscErrorCode  KSPLoad(KSP newdm, PetscViewer viewer)
     47: {
     49:   PetscBool      isbinary;
     50:   PetscInt       classid;
     51:   char           type[256];
     52:   PC             pc;

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

     60:   PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);
     61:   if (classid != KSP_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)newdm),PETSC_ERR_ARG_WRONG,"Not KSP next in file");
     62:   PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);
     63:   KSPSetType(newdm, type);
     64:   if (newdm->ops->load) {
     65:     (*newdm->ops->load)(newdm,viewer);
     66:   }
     67:   KSPGetPC(newdm,&pc);
     68:   PCLoad(pc,viewer);
     69:   return(0);
     70: }

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

     81:    Collective on KSP

     83:    Input Parameters:
     84: +  ksp - the Krylov space context
     85: -  viewer - visualization context

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

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

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

    101:    Level: beginner

    103: .keywords: KSP, view

    105: .seealso: PCView(), PetscViewerASCIIOpen()
    106: @*/
    107: PetscErrorCode  KSPView(KSP ksp,PetscViewer viewer)
    108: {
    110:   PetscBool      iascii,isbinary,isdraw;
    111: #if defined(PETSC_HAVE_SAWS)
    112:   PetscBool      issaws;
    113: #endif

    117:   if (!viewer) viewer = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)ksp));

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

    158:     PetscObjectGetComm((PetscObject)ksp,&comm);
    159:     MPI_Comm_rank(comm,&rank);
    160:     if (!rank) {
    161:       PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);
    162:       PetscStrncpy(type,((PetscObject)ksp)->type_name,256);
    163:       PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR,PETSC_FALSE);
    164:     }
    165:     if (ksp->ops->view) {
    166:       (*ksp->ops->view)(ksp,viewer);
    167:     }
    168:   } else if (isdraw) {
    169:     PetscDraw draw;
    170:     char      str[36];
    171:     PetscReal x,y,bottom,h;
    172:     PetscBool flg;

    174:     PetscViewerDrawGetDraw(viewer,0,&draw);
    175:     PetscDrawGetCurrentPoint(draw,&x,&y);
    176:     PetscObjectTypeCompare((PetscObject)ksp,KSPPREONLY,&flg);
    177:     if (!flg) {
    178:       PetscStrcpy(str,"KSP: ");
    179:       PetscStrcat(str,((PetscObject)ksp)->type_name);
    180:       PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_RED,PETSC_DRAW_BLACK,str,NULL,&h);
    181:       bottom = y - h;
    182:     } else {
    183:       bottom = y;
    184:     }
    185:     PetscDrawPushCurrentPoint(draw,x,bottom);
    186: #if defined(PETSC_HAVE_SAWS)
    187:   } else if (issaws) {
    188:     PetscMPIInt rank;
    189:     const char  *name;

    191:     PetscObjectGetName((PetscObject)ksp,&name);
    192:     MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
    193:     if (!((PetscObject)ksp)->amsmem && !rank) {
    194:       char       dir[1024];

    196:       PetscObjectViewSAWs((PetscObject)ksp,viewer);
    197:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);
    198:       PetscStackCallSAWs(SAWs_Register,(dir,&ksp->its,1,SAWs_READ,SAWs_INT));
    199:       if (!ksp->res_hist) {
    200:         KSPSetResidualHistory(ksp,NULL,PETSC_DECIDE,PETSC_TRUE);
    201:       }
    202:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/res_hist",name);
    203:       PetscStackCallSAWs(SAWs_Register,(dir,ksp->res_hist,10,SAWs_READ,SAWs_DOUBLE));
    204:     }
    205: #endif
    206:   } else if (ksp->ops->view) {
    207:     (*ksp->ops->view)(ksp,viewer);
    208:   }
    209:   if (!ksp->skippcsetfromoptions) {
    210:     if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    211:     PCView(ksp->pc,viewer);
    212:   }
    213:   if (isdraw) {
    214:     PetscDraw draw;
    215:     PetscViewerDrawGetDraw(viewer,0,&draw);
    216:     PetscDrawPopCurrentPoint(draw);
    217:   }
    218:   return(0);
    219: }

    224: /*@
    225:    KSPSetNormType - Sets the norm that is used for convergence testing.

    227:    Logically Collective on KSP

    229:    Input Parameter:
    230: +  ksp - Krylov solver context
    231: -  normtype - one of
    232: $   KSP_NORM_NONE - skips computing the norm, this should only be used if you are using
    233: $                 the Krylov method as a smoother with a fixed small number of iterations.
    234: $                 Implicitly sets KSPConvergedSkip as KSP convergence test.
    235: $   KSP_NORM_PRECONDITIONED - the default for left preconditioned solves, uses the l2 norm
    236: $                 of the preconditioned residual P^{-1}(b - A x)
    237: $   KSP_NORM_UNPRECONDITIONED - uses the l2 norm of the true b - Ax residual.
    238: $   KSP_NORM_NATURAL - supported  by KSPCG, KSPCR, KSPCGNE, KSPCGS

    241:    Options Database Key:
    242: .   -ksp_norm_type <none,preconditioned,unpreconditioned,natural>

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

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

    253:    Level: advanced

    255: .keywords: KSP, create, context, norms

    257: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetCheckNormIteration(), KSPSetPCSide(), KSPGetPCSide()
    258: @*/
    259: PetscErrorCode  KSPSetNormType(KSP ksp,KSPNormType normtype)
    260: {

    266:   ksp->normtype = ksp->normtype_set = normtype;
    267:   if (normtype == KSP_NORM_NONE) {
    268:     KSPSetConvergenceTest(ksp,KSPConvergedSkip,0,0);
    269:     PetscInfo(ksp,"Warning: setting KSPNormType to skip computing the norm\n\
    270:  KSP convergence test is implicitly set to KSPConvergedSkip\n");
    271:   }
    272:   return(0);
    273: }

    277: /*@
    278:    KSPSetCheckNormIteration - Sets the first iteration at which the norm of the residual will be
    279:      computed and used in the convergence test.

    281:    Logically Collective on KSP

    283:    Input Parameter:
    284: +  ksp - Krylov solver context
    285: -  it  - use -1 to check at all iterations

    287:    Notes:
    288:    Currently only works with KSPCG, KSPBCGS and KSPIBCGS

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

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

    296: .keywords: KSP, create, context, norms

    298: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType()
    299: @*/
    300: PetscErrorCode  KSPSetCheckNormIteration(KSP ksp,PetscInt it)
    301: {
    305:   ksp->chknorm = it;
    306:   return(0);
    307: }

    311: /*@
    312:    KSPSetLagNorm - Lags the residual norm calculation so that it is computed as part of the MPI_Allreduce() for
    313:    computing the inner products for the next iteration.  This can reduce communication costs at the expense of doing
    314:    one additional iteration.

    317:    Logically Collective on KSP

    319:    Input Parameter:
    320: +  ksp - Krylov solver context
    321: -  flg - PETSC_TRUE or PETSC_FALSE

    323:    Options Database Keys:
    324: .  -ksp_lag_norm - lag the calculated residual norm

    326:    Notes:
    327:    Currently only works with KSPIBCGS.

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

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

    334: .keywords: KSP, create, context, norms

    336: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType(), KSPSetCheckNormIteration()
    337: @*/
    338: PetscErrorCode  KSPSetLagNorm(KSP ksp,PetscBool flg)
    339: {
    343:   ksp->lagnorm = flg;
    344:   return(0);
    345: }

    349: /*@
    350:    KSPSetSupportedNorm - Sets a norm and preconditioner side supported by a KSP

    352:    Logically Collective

    354:    Input Arguments:
    355: +  ksp - Krylov method
    356: .  normtype - supported norm type
    357: .  pcside - preconditioner side that can be used with this norm
    358: -  preference - integer preference for this combination, larger values have higher priority

    360:    Level: developer

    362:    Notes:
    363:    This function should be called from the implementation files KSPCreate_XXX() to declare
    364:    which norms and preconditioner sides are supported. Users should not need to call this
    365:    function.

    367:    KSP_NORM_NONE is supported by default with all KSP methods and any PC side at priority 1.  If a KSP explicitly does
    368:    not support KSP_NORM_NONE, it should set this by setting priority=0.  Since defaulting to KSP_NORM_NONE is usually
    369:    undesirable, more desirable norms should usually have priority 2 or higher.

    371: .seealso: KSPSetNormType(), KSPSetPCSide()
    372: @*/
    373: PetscErrorCode KSPSetSupportedNorm(KSP ksp,KSPNormType normtype,PCSide pcside,PetscInt priority)
    374: {

    378:   ksp->normsupporttable[normtype][pcside] = priority;
    379:   return(0);
    380: }

    384: PetscErrorCode KSPNormSupportTableReset_Private(KSP ksp)
    385: {

    389:   PetscMemzero(ksp->normsupporttable,sizeof(ksp->normsupporttable));
    390:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_LEFT,1);
    391:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_RIGHT,1);
    392:   ksp->pc_side  = ksp->pc_side_set;
    393:   ksp->normtype = ksp->normtype_set;
    394:   return(0);
    395: }

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

    404:   best = 0;
    405:   for (i=0; i<KSP_NORM_MAX; i++) {
    406:     for (j=0; j<PC_SIDE_MAX; j++) {
    407:       if ((ksp->normtype == KSP_NORM_DEFAULT || ksp->normtype == i)
    408:           && (ksp->pc_side == PC_SIDE_DEFAULT || ksp->pc_side == j)
    409:           && (ksp->normsupporttable[i][j] > best)) {
    410:         best  = ksp->normsupporttable[i][j];
    411:         ibest = i;
    412:         jbest = j;
    413:       }
    414:     }
    415:   }
    416:   if (best < 1) {
    417:     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);
    418:     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]);
    419:     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]);
    420:     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]);
    421:   }
    422:   *normtype = (KSPNormType)ibest;
    423:   *pcside   = (PCSide)jbest;
    424:   return(0);
    425: }

    429: /*@
    430:    KSPGetNormType - Gets the norm that is used for convergence testing.

    432:    Not Collective

    434:    Input Parameter:
    435: .  ksp - Krylov solver context

    437:    Output Parameter:
    438: .  normtype - norm that is used for convergence testing

    440:    Level: advanced

    442: .keywords: KSP, create, context, norms

    444: .seealso: KSPNormType, KSPSetNormType(), KSPConvergedSkip()
    445: @*/
    446: PetscErrorCode  KSPGetNormType(KSP ksp, KSPNormType *normtype)
    447: {

    453:   KSPSetUpNorms_Private(ksp,&ksp->normtype,&ksp->pc_side);
    454:   *normtype = ksp->normtype;
    455:   return(0);
    456: }

    458: #if defined(PETSC_HAVE_SAWS)
    459: #include <petscviewersaws.h>
    460: #endif

    464: /*@
    465:    KSPSetOperators - Sets the matrix associated with the linear system
    466:    and a (possibly) different one associated with the preconditioner.

    468:    Collective on KSP and Mat

    470:    Input Parameters:
    471: +  ksp - the KSP context
    472: .  Amat - the matrix that defines the linear system
    473: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

    475:    Notes:

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

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

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

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

    488:     Level: beginner

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

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

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

    506:      and

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

    511: $         MatCreate(comm,&mat);
    512: $         MatCreate(comm,&pmat);
    513: $         KSP/PCSetOperators(ksp/pc,mat,pmat);
    514: $         PetscObjectDereference((PetscObject)mat);
    515: $         PetscObjectDereference((PetscObject)pmat);
    516: $           set size, type, etc of mat and pmat

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

    527: .keywords: KSP, set, operators, matrix, preconditioner, linear system

    529: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPGetOperators(), KSPSetComputeOperators(), KSPSetComputeInitialGuess(), KSPSetComputeRHS()
    530: @*/
    531: PetscErrorCode  KSPSetOperators(KSP ksp,Mat Amat,Mat Pmat)
    532: {

    541:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    542:   PCSetOperators(ksp->pc,Amat,Pmat);
    543:   if (ksp->setupstage == KSP_SETUP_NEWRHS) ksp->setupstage = KSP_SETUP_NEWMATRIX;  /* so that next solve call will call PCSetUp() on new matrix */
    544:   if (ksp->guess) {
    545:     KSPFischerGuessReset(ksp->guess);
    546:   }
    547:   return(0);
    548: }

    552: /*@
    553:    KSPGetOperators - Gets the matrix associated with the linear system
    554:    and a (possibly) different one associated with the preconditioner.

    556:    Collective on KSP and Mat

    558:    Input Parameter:
    559: .  ksp - the KSP context

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

    565:     Level: intermediate

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

    569: .keywords: KSP, set, get, operators, matrix, preconditioner, linear system

    571: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPSetOperators(), KSPGetOperatorsSet()
    572: @*/
    573: PetscErrorCode  KSPGetOperators(KSP ksp,Mat *Amat,Mat *Pmat)
    574: {

    579:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    580:   PCGetOperators(ksp->pc,Amat,Pmat);
    581:   return(0);
    582: }

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

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

    592:    Input Parameter:
    593: .  pc - the KSP context

    595:    Output Parameters:
    596: +  mat - the matrix associated with the linear system was set
    597: -  pmat - matrix associated with the preconditioner was set, usually the same

    599:    Level: intermediate

    601: .keywords: KSP, get, operators, matrix, linear system

    603: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperators(), PCGetOperatorsSet()
    604: @*/
    605: PetscErrorCode  KSPGetOperatorsSet(KSP ksp,PetscBool  *mat,PetscBool  *pmat)
    606: {

    611:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    612:   PCGetOperatorsSet(ksp->pc,mat,pmat);
    613:   return(0);
    614: }

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

    621:    Logically Collective on KSP

    623:    Input Parameters:
    624: +   ksp - the solver object
    625: .   presolve - the function to call before the solve
    626: -   prectx - any context needed by the function

    628:    Level: developer

    630: .keywords: KSP, create, context

    632: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPostSolve()
    633: @*/
    634: PetscErrorCode  KSPSetPreSolve(KSP ksp,PetscErrorCode (*presolve)(KSP,Vec,Vec,void*),void *prectx)
    635: {
    638:   ksp->presolve = presolve;
    639:   ksp->prectx   = prectx;
    640:   return(0);
    641: }

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

    648:    Logically Collective on KSP

    650:    Input Parameters:
    651: +   ksp - the solver object
    652: .   postsolve - the function to call after the solve
    653: -   postctx - any context needed by the function

    655:    Level: developer

    657: .keywords: KSP, create, context

    659: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPreSolve()
    660: @*/
    661: PetscErrorCode  KSPSetPostSolve(KSP ksp,PetscErrorCode (*postsolve)(KSP,Vec,Vec,void*),void *postctx)
    662: {
    665:   ksp->postsolve = postsolve;
    666:   ksp->postctx   = postctx;
    667:   return(0);
    668: }

    672: /*@
    673:    KSPCreate - Creates the default KSP context.

    675:    Collective on MPI_Comm

    677:    Input Parameter:
    678: .  comm - MPI communicator

    680:    Output Parameter:
    681: .  ksp - location to put the KSP context

    683:    Notes:
    684:    The default KSP type is GMRES with a restart of 30, using modified Gram-Schmidt
    685:    orthogonalization.

    687:    Level: beginner

    689: .keywords: KSP, create, context

    691: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP
    692: @*/
    693: PetscErrorCode  KSPCreate(MPI_Comm comm,KSP *inksp)
    694: {
    695:   KSP            ksp;
    697:   void           *ctx;

    701:   *inksp = 0;
    702:   KSPInitializePackage();

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

    706:   ksp->max_it  = 10000;
    707:   ksp->pc_side = ksp->pc_side_set = PC_SIDE_DEFAULT;
    708:   ksp->rtol    = 1.e-5;
    709: #if defined(PETSC_USE_REAL_SINGLE)
    710:   ksp->abstol  = 1.e-25;
    711: #else
    712:   ksp->abstol  = 1.e-50;
    713: #endif
    714:   ksp->divtol  = 1.e4;

    716:   ksp->chknorm        = -1;
    717:   ksp->normtype       = ksp->normtype_set = KSP_NORM_DEFAULT;
    718:   ksp->rnorm          = 0.0;
    719:   ksp->its            = 0;
    720:   ksp->guess_zero     = PETSC_TRUE;
    721:   ksp->calc_sings     = PETSC_FALSE;
    722:   ksp->res_hist       = NULL;
    723:   ksp->res_hist_alloc = NULL;
    724:   ksp->res_hist_len   = 0;
    725:   ksp->res_hist_max   = 0;
    726:   ksp->res_hist_reset = PETSC_TRUE;
    727:   ksp->numbermonitors = 0;

    729:   KSPConvergedDefaultCreate(&ctx);
    730:   KSPSetConvergenceTest(ksp,KSPConvergedDefault,ctx,KSPConvergedDefaultDestroy);
    731:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
    732:   ksp->ops->buildresidual = KSPBuildResidualDefault;

    734:   ksp->vec_sol    = 0;
    735:   ksp->vec_rhs    = 0;
    736:   ksp->pc         = 0;
    737:   ksp->data       = 0;
    738:   ksp->nwork      = 0;
    739:   ksp->work       = 0;
    740:   ksp->reason     = KSP_CONVERGED_ITERATING;
    741:   ksp->setupstage = KSP_SETUP_NEW;

    743:   KSPNormSupportTableReset_Private(ksp);

    745:   *inksp = ksp;
    746:   return(0);
    747: }

    751: /*@C
    752:    KSPSetType - Builds KSP for a particular solver.

    754:    Logically Collective on KSP

    756:    Input Parameters:
    757: +  ksp      - the Krylov space context
    758: -  type - a known method

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

    764:    Notes:
    765:    See "petsc/include/petscksp.h" for available methods (for instance,
    766:    KSPCG or KSPGMRES).

    768:   Normally, it is best to use the KSPSetFromOptions() command and
    769:   then set the KSP type from the options database rather than by using
    770:   this routine.  Using the options database provides the user with
    771:   maximum flexibility in evaluating the many different Krylov methods.
    772:   The KSPSetType() routine is provided for those situations where it
    773:   is necessary to set the iterative solver independently of the command
    774:   line or options database.  This might be the case, for example, when
    775:   the choice of iterative solver changes during the execution of the
    776:   program, and the user's application is taking responsibility for
    777:   choosing the appropriate method.  In other words, this routine is
    778:   not for beginners.

    780:   Level: intermediate

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

    785: .keywords: KSP, set, method

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

    789: @*/
    790: PetscErrorCode  KSPSetType(KSP ksp, KSPType type)
    791: {
    792:   PetscErrorCode ierr,(*r)(KSP);
    793:   PetscBool      match;

    799:   PetscObjectTypeCompare((PetscObject)ksp,type,&match);
    800:   if (match) return(0);

    802:    PetscFunctionListFind(KSPList,type,&r);
    803:   if (!r) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested KSP type %s",type);
    804:   /* Destroy the previous private KSP context */
    805:   if (ksp->ops->destroy) {
    806:     (*ksp->ops->destroy)(ksp);
    807:     ksp->ops->destroy = NULL;
    808:   }
    809:   /* Reinitialize function pointers in KSPOps structure */
    810:   PetscMemzero(ksp->ops,sizeof(struct _KSPOps));
    811:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
    812:   ksp->ops->buildresidual = KSPBuildResidualDefault;
    813:   KSPNormSupportTableReset_Private(ksp);
    814:   /* Call the KSPCreate_XXX routine for this particular Krylov solver */
    815:   ksp->setupstage = KSP_SETUP_NEW;
    816:   PetscObjectChangeTypeName((PetscObject)ksp,type);
    817:   (*r)(ksp);
    818:   return(0);
    819: }

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

    826:    Not Collective

    828:    Input Parameter:
    829: .  ksp - Krylov context

    831:    Output Parameter:
    832: .  name - name of KSP method

    834:    Level: intermediate

    836: .keywords: KSP, get, method, name

    838: .seealso: KSPSetType()
    839: @*/
    840: PetscErrorCode  KSPGetType(KSP ksp,KSPType *type)
    841: {
    845:   *type = ((PetscObject)ksp)->type_name;
    846:   return(0);
    847: }

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

    854:    Not Collective

    856:    Input Parameters:
    857: +  name_solver - name of a new user-defined solver
    858: -  routine_create - routine to create method context

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

    863:    Sample usage:
    864: .vb
    865:    KSPRegister("my_solver",MySolverCreate);
    866: .ve

    868:    Then, your solver can be chosen with the procedural interface via
    869: $     KSPSetType(ksp,"my_solver")
    870:    or at runtime via the option
    871: $     -ksp_type my_solver

    873:    Level: advanced

    875: .keywords: KSP, register

    877: .seealso: KSPRegisterAll(), KSPRegisterDestroy()

    879: @*/
    880: PetscErrorCode  KSPRegister(const char sname[],PetscErrorCode (*function)(KSP))
    881: {

    885:   PetscFunctionListAdd(&KSPList,sname,function);
    886:   return(0);
    887: }