Date: 2022-08-09T09:05:28+00:00

Actual source code: stsles.c
slepc-3.17.2 2022-08-09
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain

      6:    This file is part of SLEPc.
      7:    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
      8:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      9: */
     10: /*
     11:    ST interface routines related to the KSP object associated with it
     12: */

     14: #include <slepc/private/stimpl.h>

     16: /*
     17:    This is used to set a default type for the KSP and PC objects.
     18:    It is called at STSetFromOptions (before KSPSetFromOptions)
     19:    and also at STSetUp (in case STSetFromOptions was not called).
     20: */
     21: PetscErrorCode STSetDefaultKSP(ST st)
     22: {
     25:   if (!st->ksp) STGetKSP(st,&st->ksp);
     26:   if (st->ops->setdefaultksp) (*st->ops->setdefaultksp)(st);
     27:   PetscFunctionReturn(0);
     28: }

     30: /*
     31:    This is done by all ST types except PRECOND.
     32:    The default is an LU direct solver, or GMRES+Jacobi if matmode=shell.
     33: */
     34: PetscErrorCode STSetDefaultKSP_Default(ST st)
     35: {
     36:   PC             pc;
     37:   PCType         pctype;
     38:   KSPType        ksptype;

     40:   KSPGetPC(st->ksp,&pc);
     41:   KSPGetType(st->ksp,&ksptype);
     42:   PCGetType(pc,&pctype);
     43:   if (!pctype && !ksptype) {
     44:     if (st->Pmat || st->Psplit) {
     45:       KSPSetType(st->ksp,KSPBCGS);
     46:       PCSetType(pc,PCBJACOBI);
     47:     } else if (st->matmode == ST_MATMODE_SHELL) {
     48:       KSPSetType(st->ksp,KSPGMRES);
     49:       PCSetType(pc,PCJACOBI);
     50:     } else {
     51:       KSPSetType(st->ksp,KSPPREONLY);
     52:       PCSetType(pc,st->asymm?PCCHOLESKY:PCLU);
     53:     }
     54:   }
     55:   KSPSetErrorIfNotConverged(st->ksp,PETSC_TRUE);
     56:   PetscFunctionReturn(0);
     57: }

     59: /*@
     60:    STMatMult - Computes the matrix-vector product y = T[k] x, where T[k] is
     61:    the k-th matrix of the spectral transformation.

     63:    Neighbor-wise Collective on st

     65:    Input Parameters:
     66: +  st - the spectral transformation context
     67: .  k  - index of matrix to use
     68: -  x  - the vector to be multiplied

     70:    Output Parameter:
     71: .  y - the result

     73:    Level: developer

     75: .seealso: STMatMultTranspose()
     76: @*/
     77: PetscErrorCode STMatMult(ST st,PetscInt k,Vec x,Vec y)
     78: {
     83:   STCheckMatrices(st,1);
     86:   VecSetErrorIfLocked(y,3);

     88:   if (st->state!=ST_STATE_SETUP) STSetUp(st);
     89:   VecLockReadPush(x);
     90:   PetscLogEventBegin(ST_MatMult,st,x,y,0);
     91:   if (!st->T[k]) VecCopy(x,y); /* T[k]=NULL means identity matrix */
     92:   else MatMult(st->T[k],x,y);
     93:   PetscLogEventEnd(ST_MatMult,st,x,y,0);
     94:   VecLockReadPop(x);
     95:   PetscFunctionReturn(0);
     96: }

     98: /*@
     99:    STMatMultTranspose - Computes the matrix-vector product y = T[k]' x, where T[k] is
    100:    the k-th matrix of the spectral transformation.

    102:    Neighbor-wise Collective on st

    104:    Input Parameters:
    105: +  st - the spectral transformation context
    106: .  k  - index of matrix to use
    107: -  x  - the vector to be multiplied

    109:    Output Parameter:
    110: .  y - the result

    112:    Level: developer

    114: .seealso: STMatMult()
    115: @*/
    116: PetscErrorCode STMatMultTranspose(ST st,PetscInt k,Vec x,Vec y)
    117: {
    122:   STCheckMatrices(st,1);
    125:   VecSetErrorIfLocked(y,3);

    127:   if (st->state!=ST_STATE_SETUP) STSetUp(st);
    128:   VecLockReadPush(x);
    129:   PetscLogEventBegin(ST_MatMultTranspose,st,x,y,0);
    130:   if (!st->T[k]) VecCopy(x,y); /* T[k]=NULL means identity matrix */
    131:   else MatMultTranspose(st->T[k],x,y);
    132:   PetscLogEventEnd(ST_MatMultTranspose,st,x,y,0);
    133:   VecLockReadPop(x);
    134:   PetscFunctionReturn(0);
    135: }

    137: /*@
    138:    STMatSolve - Solves P x = b, where P is the preconditioner matrix of
    139:    the spectral transformation, using a KSP object stored internally.

    141:    Collective on st

    143:    Input Parameters:
    144: +  st - the spectral transformation context
    145: -  b  - right hand side vector

    147:    Output Parameter:
    148: .  x - computed solution

    150:    Level: developer

    152: .seealso: STMatSolveTranspose()
    153: @*/
    154: PetscErrorCode STMatSolve(ST st,Vec b,Vec x)
    155: {
    159:   STCheckMatrices(st,1);
    161:   VecSetErrorIfLocked(x,3);

    163:   if (st->state!=ST_STATE_SETUP) STSetUp(st);
    164:   VecLockReadPush(b);
    165:   PetscLogEventBegin(ST_MatSolve,st,b,x,0);
    166:   if (!st->P) VecCopy(b,x); /* P=NULL means identity matrix */
    167:   else KSPSolve(st->ksp,b,x);
    168:   PetscLogEventEnd(ST_MatSolve,st,b,x,0);
    169:   VecLockReadPop(b);
    170:   PetscFunctionReturn(0);
    171: }

    173: /*@
    174:    STMatMatSolve - Solves P X = B, where P is the preconditioner matrix of
    175:    the spectral transformation, using a KSP object stored internally.

    177:    Collective on st

    179:    Input Parameters:
    180: +  st - the spectral transformation context
    181: -  B  - right hand side vectors

    183:    Output Parameter:
    184: .  X - computed solutions

    186:    Level: developer

    188: .seealso: STMatSolve()
    189: @*/
    190: PetscErrorCode STMatMatSolve(ST st,Mat B,Mat X)
    191: {
    195:   STCheckMatrices(st,1);

    197:   if (st->state!=ST_STATE_SETUP) STSetUp(st);
    198:   PetscLogEventBegin(ST_MatSolve,st,B,X,0);
    199:   if (!st->P) MatCopy(B,X,SAME_NONZERO_PATTERN); /* P=NULL means identity matrix */
    200:   else KSPMatSolve(st->ksp,B,X);
    201:   PetscLogEventEnd(ST_MatSolve,st,B,X,0);
    202:   PetscFunctionReturn(0);
    203: }

    205: /*@
    206:    STMatSolveTranspose - Solves P' x = b, where P is the preconditioner matrix of
    207:    the spectral transformation, using a KSP object stored internally.

    209:    Collective on st

    211:    Input Parameters:
    212: +  st - the spectral transformation context
    213: -  b  - right hand side vector

    215:    Output Parameter:
    216: .  x - computed solution

    218:    Level: developer

    220: .seealso: STMatSolve()
    221: @*/
    222: PetscErrorCode STMatSolveTranspose(ST st,Vec b,Vec x)
    223: {
    227:   STCheckMatrices(st,1);
    229:   VecSetErrorIfLocked(x,3);

    231:   if (st->state!=ST_STATE_SETUP) STSetUp(st);
    232:   VecLockReadPush(b);
    233:   PetscLogEventBegin(ST_MatSolveTranspose,st,b,x,0);
    234:   if (!st->P) VecCopy(b,x); /* P=NULL means identity matrix */
    235:   else KSPSolveTranspose(st->ksp,b,x);
    236:   PetscLogEventEnd(ST_MatSolveTranspose,st,b,x,0);
    237:   VecLockReadPop(b);
    238:   PetscFunctionReturn(0);
    239: }

    241: PetscErrorCode STCheckFactorPackage(ST st)
    242: {
    243:   PC             pc;
    244:   PetscMPIInt    size;
    245:   PetscBool      flg;
    246:   MatSolverType  stype;

    248:   MPI_Comm_size(PetscObjectComm((PetscObject)st),&size);
    249:   if (size==1) PetscFunctionReturn(0);
    250:   KSPGetPC(st->ksp,&pc);
    251:   PCFactorGetMatSolverType(pc,&stype);
    252:   if (stype) {   /* currently selected PC is a factorization */
    253:     PetscStrcmp(stype,MATSOLVERPETSC,&flg);
    255:   }
    256:   PetscFunctionReturn(0);
    257: }

    259: /*@
    260:    STSetKSP - Sets the KSP object associated with the spectral
    261:    transformation.

    263:    Collective on st

    265:    Input Parameters:
    266: +  st   - the spectral transformation context
    267: -  ksp  - the linear system context

    269:    Level: advanced

    271: .seealso: STGetKSP()
    272: @*/
    273: PetscErrorCode STSetKSP(ST st,KSP ksp)
    274: {
    278:   STCheckNotSeized(st,1);
    279:   PetscObjectReference((PetscObject)ksp);
    280:   KSPDestroy(&st->ksp);
    281:   st->ksp = ksp;
    282:   PetscLogObjectParent((PetscObject)st,(PetscObject)st->ksp);
    283:   PetscFunctionReturn(0);
    284: }

    286: /*@
    287:    STGetKSP - Gets the KSP object associated with the spectral
    288:    transformation.

    290:    Not Collective

    292:    Input Parameter:
    293: .  st - the spectral transformation context

    295:    Output Parameter:
    296: .  ksp  - the linear system context

    298:    Level: intermediate

    300: .seealso: STSetKSP()
    301: @*/
    302: PetscErrorCode STGetKSP(ST st,KSP* ksp)
    303: {
    306:   if (!st->ksp) {
    307:     KSPCreate(PetscObjectComm((PetscObject)st),&st->ksp);
    308:     PetscObjectIncrementTabLevel((PetscObject)st->ksp,(PetscObject)st,1);
    309:     KSPSetOptionsPrefix(st->ksp,((PetscObject)st)->prefix);
    310:     KSPAppendOptionsPrefix(st->ksp,"st_");
    311:     PetscLogObjectParent((PetscObject)st,(PetscObject)st->ksp);
    312:     PetscObjectSetOptions((PetscObject)st->ksp,((PetscObject)st)->options);
    313:     KSPSetTolerances(st->ksp,SLEPC_DEFAULT_TOL,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);
    314:   }
    315:   *ksp = st->ksp;
    316:   PetscFunctionReturn(0);
    317: }

    319: PetscErrorCode STCheckNullSpace_Default(ST st,BV V)
    320: {
    321:   PetscInt       nc,i,c;
    322:   PetscReal      norm;
    323:   Vec            *T,w,vi;
    324:   Mat            A;
    325:   PC             pc;
    326:   MatNullSpace   nullsp;

    328:   BVGetNumConstraints(V,&nc);
    329:   PetscMalloc1(nc,&T);
    330:   if (!st->ksp) STGetKSP(st,&st->ksp);
    331:   KSPGetPC(st->ksp,&pc);
    332:   PCGetOperators(pc,&A,NULL);
    333:   MatCreateVecs(A,NULL,&w);
    334:   c = 0;
    335:   for (i=0;i<nc;i++) {
    336:     BVGetColumn(V,-nc+i,&vi);
    337:     MatMult(A,vi,w);
    338:     VecNorm(w,NORM_2,&norm);
    339:     if (norm < 10.0*PETSC_SQRT_MACHINE_EPSILON) {
    340:       PetscInfo(st,"Vector %" PetscInt_FMT " included in the nullspace of OP, norm=%g\n",i,(double)norm);
    341:       BVCreateVec(V,T+c);
    342:       VecCopy(vi,T[c]);
    343:       VecNormalize(T[c],NULL);
    344:       c++;
    345:     } else PetscInfo(st,"Vector %" PetscInt_FMT " discarded as possible nullspace of OP, norm=%g\n",i,(double)norm);
    346:     BVRestoreColumn(V,-nc+i,&vi);
    347:   }
    348:   VecDestroy(&w);
    349:   if (c>0) {
    350:     MatNullSpaceCreate(PetscObjectComm((PetscObject)st),PETSC_FALSE,c,T,&nullsp);
    351:     MatSetNullSpace(A,nullsp);
    352:     MatNullSpaceDestroy(&nullsp);
    353:     VecDestroyVecs(c,&T);
    354:   } else PetscFree(T);
    355:   PetscFunctionReturn(0);
    356: }

    358: /*@
    359:    STCheckNullSpace - Tests if constraint vectors are nullspace vectors.

    361:    Collective on st

    363:    Input Parameters:
    364: +  st - the spectral transformation context
    365: -  V  - basis vectors to be checked

    367:    Notes:
    368:    Given a basis vectors object, this function tests each of its constraint
    369:    vectors to be a nullspace vector of the coefficient matrix of the
    370:    associated KSP object. All these nullspace vectors are passed to the KSP
    371:    object.

    373:    This function allows handling singular pencils and solving some problems
    374:    in which the nullspace is important (see the users guide for details).

    376:    Level: developer

    378: .seealso: EPSSetDeflationSpace()
    379: @*/
    380: PetscErrorCode STCheckNullSpace(ST st,BV V)
    381: {
    382:   PetscInt       nc;

    390:   BVGetNumConstraints(V,&nc);
    391:   if (nc && st->ops->checknullspace) (*st->ops->checknullspace)(st,V);
    392:   PetscFunctionReturn(0);
    393: }