Date: 2013-07-02T14:47:51+00:00

Actual source code: itcreate.c
petsc-3.4.2 2013-07-02

      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,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,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_AMS)
     74: #include <petscviewerams.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_AMS)
    112:   PetscBool      isams;
    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_AMS)
    125:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERAMS,&isams);
    126: #endif
    127:   if (iascii) {
    128:     PetscObjectPrintClassNamePrefixType((PetscObject)ksp,viewer,"KSP Object");
    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",ksp->rtol,ksp->abstol,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->nullsp) {PetscViewerASCIIPrintf(viewer,"  has attached null space\n");}
    151:     if (!ksp->guess_zero) {PetscViewerASCIIPrintf(viewer,"  using nonzero initial guess\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,PETSC_FALSE);
    163:       PetscStrncpy(type,((PetscObject)ksp)->type_name,256);
    164:       PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR,PETSC_FALSE);
    165:     }
    166:     if (ksp->ops->view) {
    167:       (*ksp->ops->view)(ksp,viewer);
    168:     }
    169:   } else if (isdraw) {
    170:     PetscDraw draw;
    171:     char      str[36];
    172:     PetscReal x,y,bottom,h;
    173:     PetscBool flg;

    175:     PetscViewerDrawGetDraw(viewer,0,&draw);
    176:     PetscDrawGetCurrentPoint(draw,&x,&y);
    177:     PetscObjectTypeCompare((PetscObject)ksp,KSPPREONLY,&flg);
    178:     if (!flg) {
    179:       PetscStrcpy(str,"KSP: ");
    180:       PetscStrcat(str,((PetscObject)ksp)->type_name);
    181:       PetscDrawBoxedString(draw,x,y,PETSC_DRAW_RED,PETSC_DRAW_BLACK,str,NULL,&h);
    182:       bottom = y - h;
    183:     } else {
    184:       bottom = y;
    185:     }
    186:     PetscDrawPushCurrentPoint(draw,x,bottom);
    187: #if defined(PETSC_HAVE_AMS)
    188:   } else if (isams) {
    189:     if (((PetscObject)ksp)->amsmem == -1) {
    190:       PetscObjectViewAMS((PetscObject)ksp,viewer);
    191:       PetscStackCallAMS(AMS_Memory_take_access,(((PetscObject)ksp)->amsmem));
    192:       PetscStackCallAMS(AMS_Memory_add_field,(((PetscObject)ksp)->amsmem,"its",&ksp->its,1,AMS_INT,AMS_READ,AMS_COMMON,AMS_REDUCT_UNDEF));
    193:       if (!ksp->res_hist) {
    194:         KSPSetResidualHistory(ksp,NULL,PETSC_DECIDE,PETSC_FALSE);
    195:       }
    196:       PetscStackCallAMS(AMS_Memory_add_field,(((PetscObject)ksp)->amsmem,"res_hist",ksp->res_hist,10,AMS_DOUBLE,AMS_READ,AMS_COMMON,AMS_REDUCT_UNDEF));
    197:       PetscStackCallAMS(AMS_Memory_grant_access,(((PetscObject)ksp)->amsmem));
    198:     }
    199: #endif
    200:   } else if (ksp->ops->view) {
    201:     (*ksp->ops->view)(ksp,viewer);
    202:   }
    203:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    204:   PCView(ksp->pc,viewer);
    205:   if (isdraw) {
    206:     PetscDraw draw;
    207:     PetscViewerDrawGetDraw(viewer,0,&draw);
    208:     PetscDrawPopCurrentPoint(draw);
    209:   }
    210:   return(0);
    211: }

    216: /*@
    217:    KSPSetNormType - Sets the norm that is used for convergence testing.

    219:    Logically Collective on KSP

    221:    Input Parameter:
    222: +  ksp - Krylov solver context
    223: -  normtype - one of
    224: $   KSP_NORM_NONE - skips computing the norm, this should only be used if you are using
    225: $                 the Krylov method as a smoother with a fixed small number of iterations.
    226: $                 Implicitly sets KSPSkipConverged as KSP convergence test.
    227: $                 Supported only by CG, Richardson, Bi-CG-stab, CR, and CGS methods.
    228: $   KSP_NORM_PRECONDITIONED - the default for left preconditioned solves, uses the l2 norm
    229: $                 of the preconditioned residual
    230: $   KSP_NORM_UNPRECONDITIONED - uses the l2 norm of the true b - Ax residual, supported only by
    231: $                 CG, CHEBYSHEV, and RICHARDSON, automatically true for right (see KSPSetPCSide())
    232: $                 preconditioning..
    233: $   KSP_NORM_NATURAL - supported  by KSPCG, KSPCR, KSPCGNE, KSPCGS

    236:    Options Database Key:
    237: .   -ksp_norm_type <none,preconditioned,unpreconditioned,natural>

    239:    Notes:
    240:    Currently only works with the CG, Richardson, Bi-CG-stab, CR, and CGS methods.

    242:    Level: advanced

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

    246: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPSkipConverged(), KSPSetCheckNormIteration()
    247: @*/
    248: PetscErrorCode  KSPSetNormType(KSP ksp,KSPNormType normtype)
    249: {

    255:   ksp->normtype = normtype;
    256:   if (normtype == KSP_NORM_NONE) {
    257:     KSPSetConvergenceTest(ksp,KSPSkipConverged,0,0);
    258:     PetscInfo(ksp,"Warning: setting KSPNormType to skip computing the norm\n\
    259:  KSP convergence test is implicitly set to KSPSkipConverged\n");
    260:   }
    261:   return(0);
    262: }

    266: /*@
    267:    KSPSetCheckNormIteration - Sets the first iteration at which the norm of the residual will be
    268:      computed and used in the convergence test.

    270:    Logically Collective on KSP

    272:    Input Parameter:
    273: +  ksp - Krylov solver context
    274: -  it  - use -1 to check at all iterations

    276:    Notes:
    277:    Currently only works with KSPCG, KSPBCGS and KSPIBCGS

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

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

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

    287: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPSkipConverged(), KSPSetNormType()
    288: @*/
    289: PetscErrorCode  KSPSetCheckNormIteration(KSP ksp,PetscInt it)
    290: {
    294:   ksp->chknorm = it;
    295:   return(0);
    296: }

    300: /*@
    301:    KSPSetLagNorm - Lags the residual norm calculation so that it is computed as part of the MPI_Allreduce() for
    302:    computing the inner products for the next iteration.  This can reduce communication costs at the expense of doing
    303:    one additional iteration.

    306:    Logically Collective on KSP

    308:    Input Parameter:
    309: +  ksp - Krylov solver context
    310: -  flg - PETSC_TRUE or PETSC_FALSE

    312:    Options Database Keys:
    313: .  -ksp_lag_norm - lag the calculated residual norm

    315:    Notes:
    316:    Currently only works with KSPIBCGS.

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

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

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

    325: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPSkipConverged(), KSPSetNormType(), KSPSetCheckNormIteration()
    326: @*/
    327: PetscErrorCode  KSPSetLagNorm(KSP ksp,PetscBool flg)
    328: {
    332:   ksp->lagnorm = flg;
    333:   return(0);
    334: }

    338: /*@
    339:    KSPSetSupportedNorm - Sets a norm and preconditioner side supported by a KSP

    341:    Logically Collective

    343:    Input Arguments:
    344: +  ksp - Krylov method
    345: .  normtype - supported norm type
    346: .  pcside - preconditioner side that can be used with this norm
    347: -  preference - integer preference for this combination, larger values have higher priority

    349:    Level: developer

    351:    Notes:
    352:    This function should be called from the implementation files KSPCreate_XXX() to declare
    353:    which norms and preconditioner sides are supported. Users should not need to call this
    354:    function.

    356:    KSP_NORM_NONE is supported by default with all KSP methods and any PC side. If a KSP explicitly does not support
    357:    KSP_NORM_NONE, it should set this by setting priority=0.

    359: .seealso: KSPSetNormType(), KSPSetPCSide()
    360: @*/
    361: PetscErrorCode KSPSetSupportedNorm(KSP ksp,KSPNormType normtype,PCSide pcside,PetscInt priority)
    362: {

    366:   ksp->normsupporttable[normtype][pcside] = priority;
    367:   return(0);
    368: }

    372: PetscErrorCode KSPNormSupportTableReset_Private(KSP ksp)
    373: {

    377:   PetscMemzero(ksp->normsupporttable,sizeof(ksp->normsupporttable));
    378:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_LEFT,1);
    379:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_RIGHT,1);
    380:   return(0);
    381: }

    385: PetscErrorCode KSPSetUpNorms_Private(KSP ksp,KSPNormType *normtype,PCSide *pcside)
    386: {
    387:   PetscInt i,j,best,ibest = 0,jbest = 0;

    390:   best = 0;
    391:   for (i=0; i<KSP_NORM_MAX; i++) {
    392:     for (j=0; j<PC_SIDE_MAX; j++) {
    393:       if ((ksp->normtype == KSP_NORM_DEFAULT || ksp->normtype == i)
    394:           && (ksp->pc_side == PC_SIDE_DEFAULT || ksp->pc_side == j)
    395:           && (ksp->normsupporttable[i][j] > best)) {
    396:         if (ksp->normtype == KSP_NORM_DEFAULT && i == KSP_NORM_NONE && ksp->normsupporttable[i][j] <= 1) {
    397:           continue; /* Skip because we don't want to default to no norms unless set by the KSP (preonly). */
    398:         }
    399:         best  = ksp->normsupporttable[i][j];
    400:         ibest = i;
    401:         jbest = j;
    402:       }
    403:     }
    404:   }
    405:   if (best < 1) {
    406:     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);
    407:     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]);
    408:     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]);
    409:     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]);
    410:   }
    411:   *normtype = (KSPNormType)ibest;
    412:   *pcside   = (PCSide)jbest;
    413:   return(0);
    414: }

    418: /*@
    419:    KSPGetNormType - Gets the norm that is used for convergence testing.

    421:    Not Collective

    423:    Input Parameter:
    424: .  ksp - Krylov solver context

    426:    Output Parameter:
    427: .  normtype - norm that is used for convergence testing

    429:    Level: advanced

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

    433: .seealso: KSPNormType, KSPSetNormType(), KSPSkipConverged()
    434: @*/
    435: PetscErrorCode  KSPGetNormType(KSP ksp, KSPNormType *normtype)
    436: {

    442:   KSPSetUpNorms_Private(ksp,&ksp->normtype,&ksp->pc_side);
    443:   *normtype = ksp->normtype;
    444:   return(0);
    445: }

    447: #if defined(PETSC_HAVE_AMS)
    448: #include <petscviewerams.h>
    449: #endif

    453: /*@
    454:    KSPSetOperators - Sets the matrix associated with the linear system
    455:    and a (possibly) different one associated with the preconditioner.

    457:    Collective on KSP and Mat

    459:    Input Parameters:
    460: +  ksp - the KSP context
    461: .  Amat - the matrix that defines the linear system
    462: .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
    463: -  flag - flag indicating information about the preconditioner matrix structure
    464:    during successive linear solves.  This flag is ignored the first time a
    465:    linear system is solved, and thus is irrelevant when solving just one linear
    466:    system.

    468:    Notes:
    469:    The flag can be used to eliminate unnecessary work in the preconditioner
    470:    during the repeated solution of linear systems of the same size.  The
    471:    available options are
    472: $    SAME_PRECONDITIONER -
    473: $      Pmat is identical during successive linear solves.
    474: $      This option is intended for folks who are using
    475: $      different Amat and Pmat matrices and want to reuse the
    476: $      same preconditioner matrix.  For example, this option
    477: $      saves work by not recomputing incomplete factorization
    478: $      for ILU/ICC preconditioners.
    479: $    SAME_NONZERO_PATTERN -
    480: $      Pmat has the same nonzero structure during
    481: $      successive linear solves.
    482: $    DIFFERENT_NONZERO_PATTERN -
    483: $      Pmat does not have the same nonzero structure.

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

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

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

    493:     Caution:
    494:     If you specify SAME_NONZERO_PATTERN, PETSc believes your assertion
    495:     and does not check the structure of the matrix.  If you erroneously
    496:     claim that the structure is the same when it actually is not, the new
    497:     preconditioner will not function correctly.  Thus, use this optimization
    498:     feature carefully!

    500:     If in doubt about whether your preconditioner matrix has changed
    501:     structure or not, use the flag DIFFERENT_NONZERO_PATTERN.

    503:     Level: beginner

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

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

    516: $         MatCreate(comm,&mat);
    517: $         KSP/PCSetOperators(ksp/pc,mat,mat,SAME_NONZERO_PATTERN);
    518: $         PetscObjectDereference((PetscObject)mat);
    519: $           set size, type, etc of mat

    521:      and

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

    526: $         MatCreate(comm,&mat);
    527: $         MatCreate(comm,&pmat);
    528: $         KSP/PCSetOperators(ksp/pc,mat,pmat,SAME_NONZERO_PATTERN);
    529: $         PetscObjectDereference((PetscObject)mat);
    530: $         PetscObjectDereference((PetscObject)pmat);
    531: $           set size, type, etc of mat and pmat

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

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

    544: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPGetOperators()
    545: @*/
    546: PetscErrorCode  KSPSetOperators(KSP ksp,Mat Amat,Mat Pmat,MatStructure flag)
    547: {
    548:   MatNullSpace   nullsp;

    557:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    558:   PCSetOperators(ksp->pc,Amat,Pmat,flag);
    559:   if (ksp->setupstage == KSP_SETUP_NEWRHS) ksp->setupstage = KSP_SETUP_NEWMATRIX;  /* so that next solve call will call PCSetUp() on new matrix */
    560:   if (ksp->guess) {
    561:     KSPFischerGuessReset(ksp->guess);
    562:   }
    563:   if (Pmat) {
    564:     MatGetNullSpace(Pmat, &nullsp);
    565:     if (nullsp) {
    566:       KSPSetNullSpace(ksp, nullsp);
    567:     }
    568:   }
    569:   return(0);
    570: }

    574: /*@
    575:    KSPGetOperators - Gets the matrix associated with the linear system
    576:    and a (possibly) different one associated with the preconditioner.

    578:    Collective on KSP and Mat

    580:    Input Parameter:
    581: .  ksp - the KSP context

    583:    Output Parameters:
    584: +  Amat - the matrix that defines the linear system
    585: .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
    586: -  flag - flag indicating information about the preconditioner matrix structure
    587:    during successive linear solves.  This flag is ignored the first time a
    588:    linear system is solved, and thus is irrelevant when solving just one linear
    589:    system.

    591:     Level: intermediate

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

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

    597: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPSetOperators(), KSPGetOperatorsSet()
    598: @*/
    599: PetscErrorCode  KSPGetOperators(KSP ksp,Mat *Amat,Mat *Pmat,MatStructure *flag)
    600: {

    605:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    606:   PCGetOperators(ksp->pc,Amat,Pmat,flag);
    607:   return(0);
    608: }

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

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

    618:    Input Parameter:
    619: .  pc - the KSP context

    621:    Output Parameters:
    622: +  mat - the matrix associated with the linear system was set
    623: -  pmat - matrix associated with the preconditioner was set, usually the same

    625:    Level: intermediate

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

    629: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperators(), PCGetOperatorsSet()
    630: @*/
    631: PetscErrorCode  KSPGetOperatorsSet(KSP ksp,PetscBool  *mat,PetscBool  *pmat)
    632: {

    637:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    638:   PCGetOperatorsSet(ksp->pc,mat,pmat);
    639:   return(0);
    640: }

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

    647:    Logically Collective on KSP

    649:    Input Parameters:
    650: +   ksp - the solver object
    651: .   presolve - the function to call before the solve
    652: -   prectx - any context needed by the function

    654:    Level: developer

    656: .keywords: KSP, create, context

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

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

    674:    Logically Collective on KSP

    676:    Input Parameters:
    677: +   ksp - the solver object
    678: .   postsolve - the function to call after the solve
    679: -   postctx - any context needed by the function

    681:    Level: developer

    683: .keywords: KSP, create, context

    685: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPreSolve()
    686: @*/
    687: PetscErrorCode  KSPSetPostSolve(KSP ksp,PetscErrorCode (*postsolve)(KSP,Vec,Vec,void*),void *postctx)
    688: {
    691:   ksp->postsolve = postsolve;
    692:   ksp->postctx   = postctx;
    693:   return(0);
    694: }

    698: /*@
    699:    KSPCreate - Creates the default KSP context.

    701:    Collective on MPI_Comm

    703:    Input Parameter:
    704: .  comm - MPI communicator

    706:    Output Parameter:
    707: .  ksp - location to put the KSP context

    709:    Notes:
    710:    The default KSP type is GMRES with a restart of 30, using modified Gram-Schmidt
    711:    orthogonalization.

    713:    Level: beginner

    715: .keywords: KSP, create, context

    717: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP
    718: @*/
    719: PetscErrorCode  KSPCreate(MPI_Comm comm,KSP *inksp)
    720: {
    721:   KSP            ksp;
    723:   void           *ctx;

    727:   *inksp = 0;
    728: #if !defined(PETSC_USE_DYNAMIC_LIBRARIES)
    729:   KSPInitializePackage();
    730: #endif

    732:   PetscHeaderCreate(ksp,_p_KSP,struct _KSPOps,KSP_CLASSID,"KSP","Krylov Method","KSP",comm,KSPDestroy,KSPView);

    734:   ksp->max_it  = 10000;
    735:   ksp->pc_side = PC_SIDE_DEFAULT;
    736:   ksp->rtol    = 1.e-5;
    737:   ksp->abstol  = 1.e-50;
    738:   ksp->divtol  = 1.e4;

    740:   ksp->chknorm        = -1;
    741:   ksp->normtype       = KSP_NORM_DEFAULT;
    742:   ksp->rnorm          = 0.0;
    743:   ksp->its            = 0;
    744:   ksp->guess_zero     = PETSC_TRUE;
    745:   ksp->calc_sings     = PETSC_FALSE;
    746:   ksp->res_hist       = NULL;
    747:   ksp->res_hist_alloc = NULL;
    748:   ksp->res_hist_len   = 0;
    749:   ksp->res_hist_max   = 0;
    750:   ksp->res_hist_reset = PETSC_TRUE;
    751:   ksp->numbermonitors = 0;

    753:   KSPDefaultConvergedCreate(&ctx);
    754:   KSPSetConvergenceTest(ksp,KSPDefaultConverged,ctx,KSPDefaultConvergedDestroy);
    755:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
    756:   ksp->ops->buildresidual = KSPBuildResidualDefault;

    758:   ksp->vec_sol    = 0;
    759:   ksp->vec_rhs    = 0;
    760:   ksp->pc         = 0;
    761:   ksp->data       = 0;
    762:   ksp->nwork      = 0;
    763:   ksp->work       = 0;
    764:   ksp->reason     = KSP_CONVERGED_ITERATING;
    765:   ksp->setupstage = KSP_SETUP_NEW;

    767:   KSPNormSupportTableReset_Private(ksp);

    769:   *inksp = ksp;
    770:   return(0);
    771: }

    775: /*@C
    776:    KSPSetType - Builds KSP for a particular solver.

    778:    Logically Collective on KSP

    780:    Input Parameters:
    781: +  ksp      - the Krylov space context
    782: -  type - a known method

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

    788:    Notes:
    789:    See "petsc/include/petscksp.h" for available methods (for instance,
    790:    KSPCG or KSPGMRES).

    792:   Normally, it is best to use the KSPSetFromOptions() command and
    793:   then set the KSP type from the options database rather than by using
    794:   this routine.  Using the options database provides the user with
    795:   maximum flexibility in evaluating the many different Krylov methods.
    796:   The KSPSetType() routine is provided for those situations where it
    797:   is necessary to set the iterative solver independently of the command
    798:   line or options database.  This might be the case, for example, when
    799:   the choice of iterative solver changes during the execution of the
    800:   program, and the user's application is taking responsibility for
    801:   choosing the appropriate method.  In other words, this routine is
    802:   not for beginners.

    804:   Level: intermediate

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

    809: .keywords: KSP, set, method

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

    813: @*/
    814: PetscErrorCode  KSPSetType(KSP ksp, KSPType type)
    815: {
    816:   PetscErrorCode ierr,(*r)(KSP);
    817:   PetscBool      match;

    823:   PetscObjectTypeCompare((PetscObject)ksp,type,&match);
    824:   if (match) return(0);

    826:    PetscFunctionListFind(KSPList,type,&r);
    827:   if (!r) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested KSP type %s",type);
    828:   /* Destroy the previous private KSP context */
    829:   if (ksp->ops->destroy) {
    830:     (*ksp->ops->destroy)(ksp);
    831:     ksp->ops->destroy = NULL;
    832:   }
    833:   /* Reinitialize function pointers in KSPOps structure */
    834:   PetscMemzero(ksp->ops,sizeof(struct _KSPOps));
    835:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
    836:   ksp->ops->buildresidual = KSPBuildResidualDefault;
    837:   KSPNormSupportTableReset_Private(ksp);
    838:   /* Call the KSPCreate_XXX routine for this particular Krylov solver */
    839:   ksp->setupstage = KSP_SETUP_NEW;
    840:   PetscObjectChangeTypeName((PetscObject)ksp,type);
    841:   (*r)(ksp);
    842:   return(0);
    843: }

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

    850:    Not Collective

    852:    Input Parameter:
    853: .  ksp - Krylov context

    855:    Output Parameter:
    856: .  name - name of KSP method

    858:    Level: intermediate

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

    862: .seealso: KSPSetType()
    863: @*/
    864: PetscErrorCode  KSPGetType(KSP ksp,KSPType *type)
    865: {
    869:   *type = ((PetscObject)ksp)->type_name;
    870:   return(0);
    871: }

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

    878:    Not Collective

    880:    Input Parameters:
    881: +  name_solver - name of a new user-defined solver
    882: -  routine_create - routine to create method context

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

    887:    Sample usage:
    888: .vb
    889:    KSPRegister("my_solver",MySolverCreate);
    890: .ve

    892:    Then, your solver can be chosen with the procedural interface via
    893: $     KSPSetType(ksp,"my_solver")
    894:    or at runtime via the option
    895: $     -ksp_type my_solver

    897:    Level: advanced

    899: .keywords: KSP, register

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

    903: @*/
    904: PetscErrorCode  KSPRegister(const char sname[],PetscErrorCode (*function)(KSP))
    905: {

    909:   PetscFunctionListAdd(&KSPList,sname,function);
    910:   return(0);
    911: }

    915: /*@
    916:   KSPSetNullSpace - Sets the null space of the operator

    918:   Logically Collective on KSP

    920:   Input Parameters:
    921: +  ksp - the Krylov space object
    922: -  nullsp - the null space of the operator

    924:   Level: advanced

    926: .seealso: KSPSetOperators(), MatNullSpaceCreate(), KSPGetNullSpace(), MatSetNullSpace()
    927: @*/
    928: PetscErrorCode  KSPSetNullSpace(KSP ksp,MatNullSpace nullsp)
    929: {

    935:   PetscObjectReference((PetscObject)nullsp);
    936:   if (ksp->nullsp) { MatNullSpaceDestroy(&ksp->nullsp); }
    937:   ksp->nullsp = nullsp;
    938:   return(0);
    939: }

    943: /*@
    944:   KSPGetNullSpace - Gets the null space of the operator

    946:   Not Collective

    948:   Input Parameters:
    949: +  ksp - the Krylov space object
    950: -  nullsp - the null space of the operator

    952:   Level: advanced

    954: .seealso: KSPSetOperators(), MatNullSpaceCreate(), KSPSetNullSpace()
    955: @*/
    956: PetscErrorCode  KSPGetNullSpace(KSP ksp,MatNullSpace *nullsp)
    957: {
    961:   *nullsp = ksp->nullsp;
    962:   return(0);
    963: }