Actual source code: precond.c

  1: /*
  2:       Implements the ST class for preconditioned eigenvalue methods.

  4:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  5:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  6:    Copyright (c) 2002-2011, Universitat Politecnica de Valencia, Spain

  8:    This file is part of SLEPc.
  9:       
 10:    SLEPc is free software: you can redistribute it and/or modify it under  the
 11:    terms of version 3 of the GNU Lesser General Public License as published by
 12:    the Free Software Foundation.

 14:    SLEPc  is  distributed in the hope that it will be useful, but WITHOUT  ANY 
 15:    WARRANTY;  without even the implied warranty of MERCHANTABILITY or  FITNESS 
 16:    FOR  A  PARTICULAR PURPOSE. See the GNU Lesser General Public  License  for 
 17:    more details.

 19:    You  should have received a copy of the GNU Lesser General  Public  License
 20:    along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
 21:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 22: */

 24: #include <private/stimpl.h>          /*I "slepcst.h" I*/

 26: typedef struct {
 27:   PetscBool setmat;
 28: } ST_PRECOND;

 32: PetscErrorCode STSetFromOptions_Precond(ST st)
 33: {
 35:   PC             pc;
 36:   const PCType   pctype;
 37:   Mat            P;
 38:   PetscBool      t0,t1;
 39:   KSP            ksp;

 42:   STGetKSP(st,&ksp);
 43:   KSPGetPC(ksp,&pc);
 44:   PetscObjectGetType((PetscObject)pc,&pctype);
 45:   STPrecondGetMatForPC(st,&P);
 46:   if (!pctype && st->A) {
 47:     if (P || st->shift_matrix == ST_MATMODE_SHELL) {
 48:       PCSetType(pc,PCJACOBI);
 49:     } else {
 50:       MatHasOperation(st->A,MATOP_DUPLICATE,&t0);
 51:       if (st->B) {
 52:         MatHasOperation(st->A,MATOP_AXPY,&t1);
 53:       } else {
 54:         t1 = PETSC_TRUE;
 55:       }
 56:       PCSetType(pc,(t0 && t1)?PCJACOBI:PCNONE);
 57:     }
 58:   }
 59:   return(0);
 60: }

 64: PetscErrorCode STSetUp_Precond(ST st)
 65: {
 66:   Mat            P;
 67:   PC             pc;
 68:   PetscBool      t0,setmat,destroyP=PETSC_FALSE,builtP;

 72:   /* if the user did not set the shift, use the target value */
 73:   if (!st->sigma_set) st->sigma = st->defsigma;

 75:   /* If pc is none and no matrix has to be set, exit */
 76:   STSetFromOptions_Precond(st);
 77:   if (!st->ksp) { STGetKSP(st,&st->ksp); }
 78:   KSPGetPC(st->ksp,&pc);
 79:   PetscTypeCompare((PetscObject)pc,PCNONE,&t0);
 80:   STPrecondGetKSPHasMat(st,&setmat);
 81:   if (t0 && !setmat) return(0);

 83:   /* Check if a user matrix is set */
 84:   STPrecondGetMatForPC(st,&P);

 86:   /* If not, create A - shift*B */
 87:   if (P) {
 88:     builtP = PETSC_FALSE;
 89:     destroyP = PETSC_TRUE;
 90:     PetscObjectReference((PetscObject)P);
 91:   } else {
 92:     builtP = PETSC_TRUE;

 94:     if (!(PetscAbsScalar(st->sigma) < PETSC_MAX_REAL) && st->B) {
 95:       P = st->B;
 96:       destroyP = PETSC_FALSE;
 97:     } else if (st->sigma == 0.0) {
 98:       P = st->A;
 99:       destroyP = PETSC_FALSE;
100:     } else if (PetscAbsScalar(st->sigma) < PETSC_MAX_REAL && st->shift_matrix != ST_MATMODE_SHELL) {
101:       if (st->shift_matrix == ST_MATMODE_INPLACE) {
102:         P = st->A;
103:         destroyP = PETSC_FALSE;
104:       } else {
105:         MatDuplicate(st->A,MAT_COPY_VALUES,&P);
106:         destroyP = PETSC_TRUE;
107:       }
108:       if (st->B) {
109:         MatAXPY(P,-st->sigma,st->B,st->str);
110:       } else {
111:         MatShift(P,-st->sigma);
112:       }
113:     } else
114:       builtP = PETSC_FALSE;
115:   }

117:   /* If P was not possible to obtain, set pc to PCNONE */
118:   if (!P) {
119:     PCSetType(pc,PCNONE);

121:     /* If some matrix has to be set to ksp, a shell matrix is created */
122:     if (setmat) {
123:       STMatShellCreate(st,&P);
124:       destroyP = PETSC_TRUE;
125:     }
126:   }

128:   KSPSetOperators(st->ksp,setmat?P:PETSC_NULL,P,DIFFERENT_NONZERO_PATTERN);

130:   if (destroyP) {
131:     MatDestroy(&P);
132:   } else if (st->shift_matrix == ST_MATMODE_INPLACE && builtP) {
133:     if (st->sigma != 0.0 && PetscAbsScalar(st->sigma) < PETSC_MAX_REAL) {
134:       if (st->B) {
135:         MatAXPY(st->A,st->sigma,st->B,st->str);
136:       } else {
137:         MatShift(st->A,st->sigma);
138:       }
139:     }
140:   }
141:   return(0);
142: }

146: PetscErrorCode STSetShift_Precond(ST st,PetscScalar newshift)
147: {

151:   /* Nothing to be done if STSetUp has not been called yet */
152:   if (!st->setupcalled) return(0);
153:   st->sigma = newshift;
154:   if (st->shift_matrix != ST_MATMODE_SHELL) {
155:     STSetUp_Precond(st);
156:   }
157:   return(0);
158: }

163: PetscErrorCode STPrecondGetMatForPC_Precond(ST st,Mat *mat)
164: {
166:   PC             pc;
167:   PetscBool      flag;

170:   if (!st->ksp) { STGetKSP(st,&st->ksp); }
171:   KSPGetPC(st->ksp,&pc);
172:   PCGetOperatorsSet(pc,PETSC_NULL,&flag);
173:   if (flag) {
174:     PCGetOperators(pc,PETSC_NULL,mat,PETSC_NULL);
175:   } else *mat = PETSC_NULL;
176:   return(0);
177: }

182: /*@
183:    STPrecondGetMatForPC - Returns the matrix previously set by STPrecondSetMatForPC().

185:    Not Collective, but the Mat is shared by all processors that share the ST

187:    Input Parameter:
188: .  st - the spectral transformation context

190:    Output Parameter:
191: .  mat - the matrix that will be used in constructing the preconditioner or
192:    PETSC_NULL if no matrix was set by STPrecondSetMatForPC().

194:    Level: advanced

196: .seealso: STPrecondSetMatForPC()
197: @*/
198: PetscErrorCode STPrecondGetMatForPC(ST st,Mat *mat)
199: {

205:   PetscTryMethod(st,"STPrecondGetMatForPC_C",(ST,Mat*),(st,mat));
206:   return(0);
207: }

212: PetscErrorCode STPrecondSetMatForPC_Precond(ST st,Mat mat)
213: {
214:   PC             pc;
215:   Mat            A;
216:   PetscBool      flag;

220:   if (!st->ksp) { STGetKSP(st,&st->ksp); }
221:   KSPGetPC(st->ksp,&pc);
222:   /* Yes, all these lines are needed to safely set mat as the preconditioner
223:      matrix in pc */
224:   PCGetOperatorsSet(pc,&flag,PETSC_NULL);
225:   if (flag) {
226:     PCGetOperators(pc,&A,PETSC_NULL,PETSC_NULL);
227:     PetscObjectReference((PetscObject)A);
228:   } else
229:     A = PETSC_NULL;
230:   PetscObjectReference((PetscObject)mat);
231:   PCSetOperators(pc,A,mat,DIFFERENT_NONZERO_PATTERN);
232:   MatDestroy(&A);
233:   MatDestroy(&mat);
234:   STPrecondSetKSPHasMat(st,PETSC_TRUE);
235:   return(0);
236: }

241: /*@
242:    STPrecondSetMatForPC - Sets the matrix that must be used to build the preconditioner.

244:    Logically Collective on ST and Mat

246:    Input Parameter:
247: +  st - the spectral transformation context
248: -  mat - the matrix that will be used in constructing the preconditioner

250:    Level: advanced

252:    Notes:
253:    This matrix will be passed to the KSP object (via KSPSetOperators) as
254:    the matrix to be used when constructing the preconditioner.
255:    If no matrix is set or mat is set to PETSC_NULL, A - sigma*B will
256:    be used to build the preconditioner, being sigma the value set by STSetShift().

258: .seealso: STPrecondSetMatForPC(), STSetShift()
259: @*/
260: PetscErrorCode STPrecondSetMatForPC(ST st,Mat mat)
261: {

268:   PetscTryMethod(st,"STPrecondSetMatForPC_C",(ST,Mat),(st,mat));
269:   return(0);
270: }

275: PetscErrorCode STPrecondSetKSPHasMat_Precond(ST st,PetscBool setmat)
276: {
277:   ST_PRECOND *data = (ST_PRECOND*)st->data;

280:   data->setmat = setmat;
281:   return(0);
282: }

287: /*@
288:    STPrecondSetKSPHasMat - Sets a flag indicating that during STSetUp the coefficient
289:    matrix of the KSP linear system (A) must be set to be the same matrix as the 
290:    preconditioner (P).

292:    Collective on ST

294:    Input Parameter:
295: +  st - the spectral transformation context
296: -  setmat - the flag

298:    Notes:
299:    In most cases, the preconditioner matrix is used only in the PC object, but
300:    in external solvers this matrix must be provided also as the A-matrix in
301:    the KSP object.

303:    Level: developer

305: .seealso: STPrecondGetKSPHasMat(), STSetShift()
306: @*/
307: PetscErrorCode STPrecondSetKSPHasMat(ST st,PetscBool setmat)
308: {

314:   PetscTryMethod(st,"STPrecondSetKSPHasMat_C",(ST,PetscBool),(st,setmat));
315:   return(0);
316: }

321: PetscErrorCode STPrecondGetKSPHasMat_Precond(ST st,PetscBool *setmat)
322: {
323:   ST_PRECOND *data = (ST_PRECOND*)st->data;

326:   *setmat = data->setmat;
327:   return(0);
328: }

333: /*@
334:    STPrecondGetKSPHasMat - Returns the flag indicating if the coefficient
335:    matrix of the KSP linear system (A) is set to be the same matrix as the 
336:    preconditioner (P).

338:    Not Collective

340:    Input Parameter:
341: .  st - the spectral transformation context

343:    Output Parameter:
344: .  setmat - the flag

346:    Level: developer

348: .seealso: STPrecondSetKSPHasMat(), STSetShift()
349: @*/
350: PetscErrorCode STPrecondGetKSPHasMat(ST st,PetscBool *setmat)
351: {

357:   PetscTryMethod(st,"STPrecondGetKSPHasMat_C",(ST,PetscBool*),(st,setmat));
358:   return(0);
359: }

363: PetscErrorCode STDestroy_Precond(ST st)
364: {

368:   PetscFree(st->data);
369:   PetscObjectComposeFunctionDynamic((PetscObject)st,"STPrecondGetMatForPC_C","",PETSC_NULL);
370:   PetscObjectComposeFunctionDynamic((PetscObject)st,"STPrecondSetMatForPC_C","",PETSC_NULL);
371:   PetscObjectComposeFunctionDynamic((PetscObject)st,"STPrecondGetKSPHasMat_C","",PETSC_NULL);
372:   PetscObjectComposeFunctionDynamic((PetscObject)st,"STPrecondSetKSPHasMat_C","",PETSC_NULL);
373:   return(0);
374: }

379: PetscErrorCode STCreate_Precond(ST st)
380: {

384:   PetscNewLog(st,ST_PRECOND,&st->data);
385:   st->ops->getbilinearform = STGetBilinearForm_Default;
386:   st->ops->setup           = STSetUp_Precond;
387:   st->ops->setshift        = STSetShift_Precond;
388:   st->ops->destroy         = STDestroy_Precond;
389:   st->ops->setfromoptions  = STSetFromOptions_Precond;

391:   PetscObjectComposeFunctionDynamic((PetscObject)st,"STPrecondGetMatForPC_C","STPrecondGetMatForPC_Precond",STPrecondGetMatForPC_Precond);
392:   PetscObjectComposeFunctionDynamic((PetscObject)st,"STPrecondSetMatForPC_C","STPrecondSetMatForPC_Precond",STPrecondSetMatForPC_Precond);
393:   PetscObjectComposeFunctionDynamic((PetscObject)st,"STPrecondGetKSPHasMat_C","STPrecondGetKSPHasMat_Precond",STPrecondGetKSPHasMat_Precond);
394:   PetscObjectComposeFunctionDynamic((PetscObject)st,"STPrecondSetKSPHasMat_C","STPrecondSetKSPHasMat_Precond",STPrecondSetKSPHasMat_Precond);

396:   STPrecondSetKSPHasMat_Precond(st,PETSC_TRUE);
397:   return(0);
398: }