Actual source code: itfunc.c

  1: /*$Id: itfunc.c,v 1.159 2001/08/07 03:03:45 balay Exp $*/
  2: /*
  3:       Interface KSP routines that the user calls.
  4: */

 6:  #include src/sles/ksp/kspimpl.h

  8: /*@
  9:    KSPComputeExtremeSingularValues - Computes the extreme singular values
 10:    for the preconditioned operator. Called after or during KSPSolve()
 11:    (SLESSolve()).

 13:    Not Collective

 15:    Input Parameter:
 16: .  ksp - iterative context obtained from KSPCreate()

 18:    Output Parameters:
 19: .  emin, emax - extreme singular values

 21:    Notes:
 22:    One must call KSPSetComputeSingularValues() before calling KSPSetUp() 
 23:    (or use the option -ksp_compute_eigenvalues) in order for this routine to work correctly.

 25:    Many users may just want to use the monitoring routine
 26:    KSPSingularValueMonitor() (which can be set with option -ksp_singmonitor)
 27:    to print the extreme singular values at each iteration of the linear solve.

 29:    Level: advanced

 31: .keywords: KSP, compute, extreme, singular, values

 33: .seealso: KSPSetComputeSingularValues(), KSPSingularValueMonitor(), KSPComputeEigenvalues()
 34: @*/
 35: int KSPComputeExtremeSingularValues(KSP ksp,PetscReal *emax,PetscReal *emin)
 36: {

 43:   if (!ksp->calc_sings) {
 44:     SETERRQ(4,"Singular values not requested before KSPSetUp()");
 45:   }

 47:   if (ksp->ops->computeextremesingularvalues) {
 48:     (*ksp->ops->computeextremesingularvalues)(ksp,emax,emin);
 49:   }
 50:   return(0);
 51: }

 53: /*@
 54:    KSPComputeEigenvalues - Computes the extreme eigenvalues for the
 55:    preconditioned operator. Called after or during KSPSolve() (SLESSolve()).

 57:    Not Collective

 59:    Input Parameter:
 60: +  ksp - iterative context obtained from KSPCreate()
 61: -  n - size of arrays r and c. The number of eigenvalues computed (neig) will, in 
 62:        general, be less than this.

 64:    Output Parameters:
 65: +  r - real part of computed eigenvalues
 66: .  c - complex part of computed eigenvalues
 67: -  neig - number of eigenvalues computed (will be less than or equal to n)

 69:    Options Database Keys:
 70: +  -ksp_compute_eigenvalues - Prints eigenvalues to stdout
 71: -  -ksp_plot_eigenvalues - Plots eigenvalues in an x-window display

 73:    Notes:
 74:    The number of eigenvalues estimated depends on the size of the Krylov space
 75:    generated during the KSPSolve() (that is the SLESSolve); for example, with 
 76:    CG it corresponds to the number of CG iterations, for GMRES it is the number 
 77:    of GMRES iterations SINCE the last restart. Any extra space in r[] and c[]
 78:    will be ignored.

 80:    KSPComputeEigenvalues() does not usually provide accurate estimates; it is
 81:    intended only for assistance in understanding the convergence of iterative 
 82:    methods, not for eigenanalysis. 

 84:    One must call KSPSetComputeEigenvalues() before calling KSPSetUp() 
 85:    in order for this routine to work correctly.

 87:    Many users may just want to use the monitoring routine
 88:    KSPSingularValueMonitor() (which can be set with option -ksp_singmonitor)
 89:    to print the singular values at each iteration of the linear solve.

 91:    Level: advanced

 93: .keywords: KSP, compute, extreme, singular, values

 95: .seealso: KSPSetComputeSingularValues(), KSPSingularValueMonitor(), KSPComputeExtremeSingularValues()
 96: @*/
 97: int KSPComputeEigenvalues(KSP ksp,int n,PetscReal *r,PetscReal *c,int *neig)
 98: {

105:   if (!ksp->calc_sings) {
106:     SETERRQ(4,"Eigenvalues not requested before KSPSetUp()");
107:   }

109:   if (ksp->ops->computeeigenvalues) {
110:     (*ksp->ops->computeeigenvalues)(ksp,n,r,c,neig);
111:   }
112:   return(0);
113: }

115: /*@
116:    KSPSetUp - Sets up the internal data structures for the
117:    later use of an iterative solver.

119:    Collective on KSP

121:    Input Parameter:
122: .  ksp   - iterative context obtained from KSPCreate()

124:    Level: developer

126: .keywords: KSP, setup

128: .seealso: KSPCreate(), KSPSolve(), KSPDestroy()
129: @*/
130: int KSPSetUp(KSP ksp)
131: {


137:   /* reset the convergence flag from the previous solves */
138:   ksp->reason = KSP_CONVERGED_ITERATING;

140:   if (!ksp->type_name){
141:     KSPSetType(ksp,KSPGMRES);
142:   }

144:   if (ksp->setupcalled) return(0);
145:   ksp->setupcalled = 1;
146:   (*ksp->ops->setup)(ksp);
147:   return(0);
148: }


151: /*@
152:    KSPSolve - Solves linear system; usually not called directly, rather 
153:    it is called by a call to SLESSolve().

155:    Collective on KSP

157:    Input Parameter:
158: .  ksp - iterative context obtained from KSPCreate()

160:    Output Parameter:
161: .  its - number of iterations required

163:    Options Database:
164: +  -ksp_compute_eigenvalues - compute preconditioned operators eigenvalues
165: .  -ksp_plot_eigenvalues - plot the computed eigenvalues in an X-window
166: .  -ksp_compute_eigenvalues_explicitly - compute the eigenvalues by forming the 
167:       dense operator and useing LAPACK
168: -  -ksp_plot_eigenvalues_explicitly - plot the explicitly computing eigenvalues

170:    Notes:
171:    On return, the parameter "its" contains either the iteration
172:    number at which convergence was successfully reached or failure was detected.

174:    Call KSPGetConvergedReason() to determine if the solver converged or failed and 
175:    why.
176:    
177:    If using a direct method (e.g., via the KSP solver
178:    KSPPREONLY and a preconditioner such as PCLU/PCILU),
179:    then its=1.  See KSPSetTolerances() and KSPDefaultConverged()
180:    for more details.

182:    Understanding Convergence:
183:    The routines KSPSetMonitor(), KSPComputeEigenvalues(), and
184:    KSPComputeEigenvaluesExplicitly() provide information on additional
185:    options to monitor convergence and print eigenvalue information.

187:    Level: developer

189: .keywords: KSP, solve, linear system

191: .seealso: KSPCreate(), KSPSetUp(), KSPDestroy(), KSPSetTolerances(), KSPDefaultConverged(),
192:           SLESSolve(), KSPSolveTranspose(), SLESGetKSP()
193: @*/
194: int KSPSolve(KSP ksp,int *its)
195: {
196:   int          ierr,rank,nits;
197:   PetscTruth   flag1,flag2;
198:   PetscScalar  zero = 0.0;


203:   if (!ksp->setupcalled){ KSPSetUp(ksp);}
204:   if (ksp->guess_zero) { VecSet(&zero,ksp->vec_sol);}
205:   /* reset the residual history list if requested */
206:   if (ksp->res_hist_reset) ksp->res_hist_len = 0;

208:   ksp->transpose_solve = PETSC_FALSE;
209:   (*ksp->ops->solve)(ksp,&nits);
210:   if (!ksp->reason) {
211:     SETERRQ(1,"Internal error, solver returned without setting converged reason");
212:   }
213:   if (its) *its = nits;

215:   MPI_Comm_rank(ksp->comm,&rank);

217:   PetscOptionsHasName(ksp->prefix,"-ksp_compute_eigenvalues",&flag1);
218:   PetscOptionsHasName(ksp->prefix,"-ksp_plot_eigenvalues",&flag2);
219:   if (flag1 || flag2) {
220:     int       n = nits + 2,i,neig;
221:     PetscReal *r,*c;

223:     if (!n) {
224:       PetscPrintf(ksp->comm,"Zero iterations in solver, cannot approximate any eigenvaluesn");
225:     } else {
226:       PetscMalloc(2*n*sizeof(PetscReal),&r);
227:       c = r + n;
228:       KSPComputeEigenvalues(ksp,n,r,c,&neig);
229:       if (flag1) {
230:         PetscPrintf(ksp->comm,"Iteratively computed eigenvaluesn");
231:         for (i=0; i<neig; i++) {
232:           if (c[i] >= 0.0) {PetscPrintf(ksp->comm,"%g + %gin",r[i],c[i]);}
233:           else             {PetscPrintf(ksp->comm,"%g - %gin",r[i],-c[i]);}
234:         }
235:       }
236:       if (flag2 && !rank) {
237:         PetscViewer viewer;
238:         PetscDraw   draw;
239:         PetscDrawSP drawsp;

241:         PetscViewerDrawOpen(PETSC_COMM_SELF,0,"Iteratively Computed Eigenvalues",
242:                                PETSC_DECIDE,PETSC_DECIDE,300,300,&viewer);
243:         PetscViewerDrawGetDraw(viewer,0,&draw);
244:         PetscDrawSPCreate(draw,1,&drawsp);
245:         for (i=0; i<neig; i++) {
246:           PetscDrawSPAddPoint(drawsp,r+i,c+i);
247:         }
248:         PetscDrawSPDraw(drawsp);
249:         PetscDrawSPDestroy(drawsp);
250:         PetscViewerDestroy(viewer);
251:       }
252:       PetscFree(r);
253:     }
254:   }

256:   PetscOptionsHasName(ksp->prefix,"-ksp_compute_eigenvalues_explicitly",&flag1);
257:   PetscOptionsHasName(ksp->prefix,"-ksp_plot_eigenvalues_explicitly",&flag2);
258:   if (flag1 || flag2) {
259:     int       n,i;
260:     PetscReal *r,*c;
261:     VecGetSize(ksp->vec_sol,&n);
262:     PetscMalloc(2*n*sizeof(PetscReal),&r);
263:     c = r + n;
264:     KSPComputeEigenvaluesExplicitly(ksp,n,r,c);
265:     if (flag1) {
266:       PetscPrintf(ksp->comm,"Explicitly computed eigenvaluesn");
267:       for (i=0; i<n; i++) {
268:         if (c[i] >= 0.0) {PetscPrintf(ksp->comm,"%g + %gin",r[i],c[i]);}
269:         else             {PetscPrintf(ksp->comm,"%g - %gin",r[i],-c[i]);}
270:       }
271:     }
272:     if (flag2 && !rank) {
273:       PetscViewer viewer;
274:       PetscDraw   draw;
275:       PetscDrawSP drawsp;

277:       PetscViewerDrawOpen(PETSC_COMM_SELF,0,"Explicitly Computed Eigenvalues",0,320,300,300,&viewer);
278:       PetscViewerDrawGetDraw(viewer,0,&draw);
279:       PetscDrawSPCreate(draw,1,&drawsp);
280:       for (i=0; i<n; i++) {
281:         PetscDrawSPAddPoint(drawsp,r+i,c+i);
282:       }
283:       PetscDrawSPDraw(drawsp);
284:       PetscDrawSPDestroy(drawsp);
285:       PetscViewerDestroy(viewer);
286:     }
287:     PetscFree(r);
288:   }

290:   PetscOptionsHasName(ksp->prefix,"-ksp_view_operator",&flag2);
291:   if (flag2) {
292:     Mat A,B;
293:     PCGetOperators(ksp->B,&A,PETSC_NULL,PETSC_NULL);
294:     MatComputeExplicitOperator(A,&B);
295:     PetscViewerPushFormat(PETSC_VIEWER_STDOUT_(ksp->comm),PETSC_VIEWER_ASCII_MATLAB);
296:     MatView(B,PETSC_VIEWER_STDOUT_(ksp->comm));
297:     PetscViewerPopFormat(PETSC_VIEWER_STDOUT_(ksp->comm));
298:     MatDestroy(B);
299:   }
300:   return(0);
301: }

303: /*@
304:    KSPSolveTranspose - Solves the transpose of a linear system. Usually
305:    accessed through SLESSolveTranspose().

307:    Collective on KSP

309:    Input Parameter:
310: .  ksp - iterative context obtained from KSPCreate()

312:    Output Parameter:
313: .  its - number of iterations required

315:    Notes:
316:    On return, the parameter "its" contains either the iteration
317:    number at which convergence was successfully reached, or the
318:    negative of the iteration at which divergence or breakdown was detected.

320:    Currently only supported by KSPType of KSPPREONLY. This routine is usally 
321:    only used internally by the BiCG solver on the subblocks in BJacobi and ASM.

323:    Level: developer

325: .keywords: KSP, solve, linear system

327: .seealso: KSPCreate(), KSPSetUp(), KSPDestroy(), KSPSetTolerances(), KSPDefaultConverged(),
328:           SLESSolve(), SLESGetKSP()
329: @*/
330: int KSPSolveTranspose(KSP ksp,int *its)
331: {
332:   int           ierr;
333:   PetscScalar   zero = 0.0;


338:   if (!ksp->setupcalled){ KSPSetUp(ksp);}
339:   if (ksp->guess_zero) { VecSet(&zero,ksp->vec_sol);}
340:   ksp->transpose_solve = PETSC_TRUE;
341:   (*ksp->ops->solve)(ksp,its);
342:   return(0);
343: }

345: /*@C
346:    KSPDestroy - Destroys KSP context.

348:    Collective on KSP

350:    Input Parameter:
351: .  ksp - iterative context obtained from KSPCreate()

353:    Level: developer

355: .keywords: KSP, destroy

357: .seealso: KSPCreate(), KSPSetUp(), KSPSolve()
358: @*/
359: int KSPDestroy(KSP ksp)
360: {
361:   int i,ierr;

365:   if (--ksp->refct > 0) return(0);

367:   /* if memory was published with AMS then destroy it */
368:   PetscObjectDepublish(ksp);

370:   if (ksp->ops->destroy) {
371:     (*ksp->ops->destroy)(ksp);
372:   }
373:   for (i=0; i<ksp->numbermonitors; i++) {
374:     if (ksp->monitordestroy[i]) {
375:       (*ksp->monitordestroy[i])(ksp->monitorcontext[i]);
376:     }
377:   }
378:   PetscLogObjectDestroy(ksp);
379:   PetscHeaderDestroy(ksp);
380:   return(0);
381: }

383: /*@
384:     KSPSetPreconditionerSide - Sets the preconditioning side.

386:     Collective on KSP

388:     Input Parameter:
389: .   ksp - iterative context obtained from KSPCreate()

391:     Output Parameter:
392: .   side - the preconditioning side, where side is one of
393: .vb
394:       PC_LEFT - left preconditioning (default)
395:       PC_RIGHT - right preconditioning
396:       PC_SYMMETRIC - symmetric preconditioning
397: .ve

399:     Options Database Keys:
400: +   -ksp_left_pc - Sets left preconditioning
401: .   -ksp_right_pc - Sets right preconditioning
402: -   -ksp_symmetric_pc - Sets symmetric preconditioning

404:     Notes:
405:     Left preconditioning is used by default.  Symmetric preconditioning is
406:     currently available only for the KSPQCG method. Note, however, that
407:     symmetric preconditioning can be emulated by using either right or left
408:     preconditioning and a pre or post processing step.

410:     Level: intermediate

412: .keywords: KSP, set, right, left, symmetric, side, preconditioner, flag

414: .seealso: KSPGetPreconditionerSide()
415: @*/
416: int KSPSetPreconditionerSide(KSP ksp,PCSide side)
417: {
420:   ksp->pc_side = side;
421:   return(0);
422: }

424: /*@C
425:     KSPGetPreconditionerSide - Gets the preconditioning side.

427:     Not Collective

429:     Input Parameter:
430: .   ksp - iterative context obtained from KSPCreate()

432:     Output Parameter:
433: .   side - the preconditioning side, where side is one of
434: .vb
435:       PC_LEFT - left preconditioning (default)
436:       PC_RIGHT - right preconditioning
437:       PC_SYMMETRIC - symmetric preconditioning
438: .ve

440:     Level: intermediate

442: .keywords: KSP, get, right, left, symmetric, side, preconditioner, flag

444: .seealso: KSPSetPreconditionerSide()
445: @*/
446: int KSPGetPreconditionerSide(KSP ksp,PCSide *side)
447: {
450:   *side = ksp->pc_side;
451:   return(0);
452: }

454: /*@
455:    KSPGetTolerances - Gets the relative, absolute, divergence, and maximum
456:    iteration tolerances used by the default KSP convergence tests. 

458:    Not Collective

460:    Input Parameter:
461: .  ksp - the Krylov subspace context
462:   
463:    Output Parameters:
464: +  rtol - the relative convergence tolerance
465: .  atol - the absolute convergence tolerance
466: .  dtol - the divergence tolerance
467: -  maxits - maximum number of iterations

469:    Notes:
470:    The user can specify PETSC_NULL for any parameter that is not needed.

472:    Level: intermediate

474: .keywords: KSP, get, tolerance, absolute, relative, divergence, convergence,
475:            maximum, iterations

477: .seealso: KSPSetTolerances()
478: @*/
479: int KSPGetTolerances(KSP ksp,PetscReal *rtol,PetscReal *atol,PetscReal *dtol,int *maxits)
480: {
483:   if (atol)   *atol   = ksp->atol;
484:   if (rtol)   *rtol   = ksp->rtol;
485:   if (dtol)   *dtol   = ksp->divtol;
486:   if (maxits) *maxits = ksp->max_it;
487:   return(0);
488: }

490: /*@
491:    KSPSetTolerances - Sets the relative, absolute, divergence, and maximum
492:    iteration tolerances used by the default KSP convergence testers. 

494:    Collective on KSP

496:    Input Parameters:
497: +  ksp - the Krylov subspace context
498: .  rtol - the relative convergence tolerance
499:    (relative decrease in the residual norm)
500: .  atol - the absolute convergence tolerance 
501:    (absolute size of the residual norm)
502: .  dtol - the divergence tolerance
503:    (amount residual can increase before KSPDefaultConverged()
504:    concludes that the method is diverging)
505: -  maxits - maximum number of iterations to use

507:    Options Database Keys:
508: +  -ksp_atol <atol> - Sets atol
509: .  -ksp_rtol <rtol> - Sets rtol
510: .  -ksp_divtol <dtol> - Sets dtol
511: -  -ksp_max_it <maxits> - Sets maxits

513:    Notes:
514:    Use PETSC_DEFAULT to retain the default value of any of the tolerances.

516:    See KSPDefaultConverged() for details on the use of these parameters
517:    in the default convergence test.  See also KSPSetConvergenceTest() 
518:    for setting user-defined stopping criteria.

520:    Level: intermediate

522: .keywords: KSP, set, tolerance, absolute, relative, divergence, 
523:            convergence, maximum, iterations

525: .seealso: KSPGetTolerances(), KSPDefaultConverged(), KSPSetConvergenceTest()
526: @*/
527: int KSPSetTolerances(KSP ksp,PetscReal rtol,PetscReal atol,PetscReal dtol,int maxits)
528: {
531:   if (atol != PETSC_DEFAULT)   ksp->atol   = atol;
532:   if (rtol != PETSC_DEFAULT)   ksp->rtol   = rtol;
533:   if (dtol != PETSC_DEFAULT)   ksp->divtol = dtol;
534:   if (maxits != PETSC_DEFAULT) ksp->max_it = maxits;
535:   return(0);
536: }

538: /*@
539:    KSPSetInitialGuessNonzero - Tells the iterative solver that the 
540:    initial guess is nonzero; otherwise KSP assumes the initial guess
541:    is to be zero (and thus zeros it out before solving).

543:    Collective on KSP

545:    Input Parameters:
546: +  ksp - iterative context obtained from SLESGetKSP() or KSPCreate()
547: -  flg - PETSC_TRUE or PETSC_FALSE

549:    Level: beginner

551:    Notes:
552:     If this is not called the X vector is zeroed in the call to 
553: SLESSolve() (or KSPSolve()).

555: .keywords: KSP, set, initial guess, nonzero

557: .seealso: KSPGetIntialGuessNonzero()
558: @*/
559: int KSPSetInitialGuessNonzero(KSP ksp,PetscTruth flg)
560: {
562:   ksp->guess_zero   = (PetscTruth)!(int)flg;
563:   return(0);
564: }

566: /*@
567:    KSPGetInitialGuessNonzero - Determines whether the KSP solver is using
568:    a zero initial guess.

570:    Not Collective

572:    Input Parameter:
573: .  ksp - iterative context obtained from KSPCreate()

575:    Output Parameter:
576: .  flag - PETSC_TRUE if guess is nonzero, else PETSC_FALSE

578:    Level: intermediate

580: .keywords: KSP, set, initial guess, nonzero

582: .seealso: KSPSetIntialGuessNonzero()
583: @*/
584: int KSPGetInitialGuessNonzero(KSP ksp,PetscTruth *flag)
585: {
587:   if (ksp->guess_zero) *flag = PETSC_FALSE;
588:   else                 *flag = PETSC_TRUE;
589:   return(0);
590: }

592: /*@
593:    KSPSetComputeSingularValues - Sets a flag so that the extreme singular 
594:    values will be calculated via a Lanczos or Arnoldi process as the linear 
595:    system is solved.

597:    Collective on KSP

599:    Input Parameters:
600: +  ksp - iterative context obtained from KSPCreate()
601: -  flg - PETSC_TRUE or PETSC_FALSE

603:    Options Database Key:
604: .  -ksp_singmonitor - Activates KSPSetComputeSingularValues()

606:    Notes:
607:    Currently this option is not valid for all iterative methods.

609:    Many users may just want to use the monitoring routine
610:    KSPSingularValueMonitor() (which can be set with option -ksp_singmonitor)
611:    to print the singular values at each iteration of the linear solve.

613:    Level: advanced

615: .keywords: KSP, set, compute, singular values

617: .seealso: KSPComputeExtremeSingularValues(), KSPSingularValueMonitor()
618: @*/
619: int KSPSetComputeSingularValues(KSP ksp,PetscTruth flg)
620: {
623:   ksp->calc_sings  = flg;
624:   return(0);
625: }

627: /*@
628:    KSPSetComputeEigenvalues - Sets a flag so that the extreme eigenvalues
629:    values will be calculated via a Lanczos or Arnoldi process as the linear 
630:    system is solved.

632:    Collective on KSP

634:    Input Parameters:
635: +  ksp - iterative context obtained from KSPCreate()
636: -  flg - PETSC_TRUE or PETSC_FALSE

638:    Notes:
639:    Currently this option is not valid for all iterative methods.

641:    Level: advanced

643: .keywords: KSP, set, compute, eigenvalues

645: .seealso: KSPComputeEigenvalues(), KSPComputeEigenvaluesExplicitly()
646: @*/
647: int KSPSetComputeEigenvalues(KSP ksp,PetscTruth flg)
648: {
651:   ksp->calc_sings  = flg;
652:   return(0);
653: }

655: /*@
656:    KSPSetRhs - Sets the right-hand-side vector for the linear system to
657:    be solved.

659:    Collective on KSP and Vec

661:    Input Parameters:
662: +  ksp - iterative context obtained from KSPCreate()
663: -  b   - right-hand-side vector

665:    Level: developer

667: .keywords: KSP, set, right-hand-side, rhs

669: .seealso: KSPGetRhs(), KSPSetSolution()
670: @*/
671: int KSPSetRhs(KSP ksp,Vec b)
672: {
676:   ksp->vec_rhs    = (b);
677:   return(0);
678: }

680: /*@C
681:    KSPGetRhs - Gets the right-hand-side vector for the linear system to
682:    be solved.

684:    Not Collective

686:    Input Parameter:
687: .  ksp - iterative context obtained from KSPCreate()

689:    Output Parameter:
690: .  r - right-hand-side vector

692:    Level: developer

694: .keywords: KSP, get, right-hand-side, rhs

696: .seealso: KSPSetRhs(), KSPGetSolution()
697: @*/
698: int KSPGetRhs(KSP ksp,Vec *r)
699: {
702:   *r = ksp->vec_rhs;
703:   return(0);
704: }

706: /*@
707:    KSPSetSolution - Sets the location of the solution for the 
708:    linear system to be solved.

710:    Collective on KSP and Vec

712:    Input Parameters:
713: +  ksp - iterative context obtained from KSPCreate()
714: -  x   - solution vector

716:    Level: developer

718: .keywords: KSP, set, solution

720: .seealso: KSPSetRhs(), KSPGetSolution()
721: @*/
722: int KSPSetSolution(KSP ksp,Vec x)
723: {
727:   ksp->vec_sol    = (x);
728:   return(0);
729: }

731: /*@C
732:    KSPGetSolution - Gets the location of the solution for the 
733:    linear system to be solved.  Note that this may not be where the solution
734:    is stored during the iterative process; see KSPBuildSolution().

736:    Not Collective

738:    Input Parameters:
739: .  ksp - iterative context obtained from KSPCreate()

741:    Output Parameters:
742: .  v - solution vector

744:    Level: developer

746: .keywords: KSP, get, solution

748: .seealso: KSPGetRhs(), KSPSetSolution(), KSPBuildSolution()
749: @*/
750: int KSPGetSolution(KSP ksp,Vec *v)
751: {
754:   *v = ksp->vec_sol;
755:   return(0);
756: }

758: /*@
759:    KSPSetPC - Sets the preconditioner to be used to calculate the 
760:    application of the preconditioner on a vector. 

762:    Collective on KSP

764:    Input Parameters:
765: +  ksp - iterative context obtained from KSPCreate()
766: -  B   - the preconditioner object

768:    Notes:
769:    Use KSPGetPC() to retrieve the preconditioner context (for example,
770:    to free it at the end of the computations).

772:    Level: developer

774: .keywords: KSP, set, precondition, Binv

776: .seealso: KSPGetPC()
777: @*/
778: int KSPSetPC(KSP ksp,PC B)
779: {
784:   ksp->B = B;
785:   return(0);
786: }

788: /*@C
789:    KSPGetPC - Returns a pointer to the preconditioner context
790:    set with KSPSetPC().

792:    Not Collective

794:    Input Parameters:
795: .  ksp - iterative context obtained from KSPCreate()

797:    Output Parameter:
798: .  B - preconditioner context

800:    Level: developer

802: .keywords: KSP, get, preconditioner, Binv

804: .seealso: KSPSetPC()
805: @*/
806: int KSPGetPC(KSP ksp,PC *B)
807: {
810:   *B = ksp->B;
811:   return(0);
812: }

814: /*@C
815:    KSPSetMonitor - Sets an ADDITIONAL function to be called at every iteration to monitor 
816:    the residual/error etc.
817:       
818:    Collective on KSP

820:    Input Parameters:
821: +  ksp - iterative context obtained from KSPCreate()
822: .  monitor - pointer to function (if this is PETSC_NULL, it turns off monitoring
823: .  mctx    - [optional] context for private data for the
824:              monitor routine (use PETSC_NULL if no context is desired)
825: -  monitordestroy - [optional] routine that frees monitor context
826:           (may be PETSC_NULL)

828:    Calling Sequence of monitor:
829: $     monitor (KSP ksp, int it, PetscReal rnorm, void *mctx)

831: +  ksp - iterative context obtained from KSPCreate()
832: .  it - iteration number
833: .  rnorm - (estimated) 2-norm of (preconditioned) residual
834: -  mctx  - optional monitoring context, as set by KSPSetMonitor()

836:    Options Database Keys:
837: +    -ksp_monitor        - sets KSPDefaultMonitor()
838: .    -ksp_truemonitor    - sets KSPTrueMonitor()
839: .    -ksp_xmonitor       - sets line graph monitor,
840:                            uses KSPLGMonitorCreate()
841: .    -ksp_xtruemonitor   - sets line graph monitor,
842:                            uses KSPLGMonitorCreate()
843: .    -ksp_singmonitor    - sets KSPSingularValueMonitor()
844: -    -ksp_cancelmonitors - cancels all monitors that have
845:                           been hardwired into a code by 
846:                           calls to KSPSetMonitor(), but
847:                           does not cancel those set via
848:                           the options database.

850:    Notes:  
851:    The default is to do nothing.  To print the residual, or preconditioned 
852:    residual if KSPSetNormType(ksp,KSP_PRECONDITIONED_NORM) was called, use 
853:    KSPDefaultMonitor() as the monitoring routine, with a null monitoring 
854:    context. 

856:    Several different monitoring routines may be set by calling
857:    KSPSetMonitor() multiple times; all will be called in the 
858:    order in which they were set.

860:    Level: beginner

862: .keywords: KSP, set, monitor

864: .seealso: KSPDefaultMonitor(), KSPLGMonitorCreate(), KSPClearMonitor()
865: @*/
866: int KSPSetMonitor(KSP ksp,int (*monitor)(KSP,int,PetscReal,void*),void *mctx,int (*monitordestroy)(void*))
867: {
870:   if (ksp->numbermonitors >= MAXKSPMONITORS) {
871:     SETERRQ(PETSC_ERR_ARG_OUTOFRANGE,"Too many KSP monitors set");
872:   }
873:   ksp->monitor[ksp->numbermonitors]           = monitor;
874:   ksp->monitordestroy[ksp->numbermonitors]    = monitordestroy;
875:   ksp->monitorcontext[ksp->numbermonitors++]  = (void*)mctx;
876:   return(0);
877: }

879: /*@
880:    KSPClearMonitor - Clears all monitors for a KSP object.

882:    Collective on KSP

884:    Input Parameters:
885: .  ksp - iterative context obtained from KSPCreate()

887:    Options Database Key:
888: .  -ksp_cancelmonitors - Cancels all monitors that have
889:     been hardwired into a code by calls to KSPSetMonitor(), 
890:     but does not cancel those set via the options database.

892:    Level: intermediate

894: .keywords: KSP, set, monitor

896: .seealso: KSPDefaultMonitor(), KSPLGMonitorCreate(), KSPSetMonitor()
897: @*/
898: int KSPClearMonitor(KSP ksp)
899: {
902:   ksp->numbermonitors = 0;
903:   return(0);
904: }

906: /*@C
907:    KSPGetMonitorContext - Gets the monitoring context, as set by 
908:    KSPSetMonitor() for the FIRST monitor only.

910:    Not Collective

912:    Input Parameter:
913: .  ksp - iterative context obtained from KSPCreate()

915:    Output Parameter:
916: .  ctx - monitoring context

918:    Level: intermediate

920: .keywords: KSP, get, monitor, context

922: .seealso: KSPDefaultMonitor(), KSPLGMonitorCreate()
923: @*/
924: int KSPGetMonitorContext(KSP ksp,void **ctx)
925: {
928:   *ctx =      (ksp->monitorcontext[0]);
929:   return(0);
930: }

932: /*@
933:    KSPSetResidualHistory - Sets the array used to hold the residual history.
934:    If set, this array will contain the residual norms computed at each
935:    iteration of the solver.

937:    Not Collective

939:    Input Parameters:
940: +  ksp - iterative context obtained from KSPCreate()
941: .  a   - array to hold history
942: .  na  - size of a
943: -  reset - PETSC_TRUE indicates the history counter is reset to zero
944:            for each new linear solve

946:    Level: advanced

948: .keywords: KSP, set, residual, history, norm

950: .seealso: KSPGetResidualHistory()

952: @*/
953: int KSPSetResidualHistory(KSP ksp,PetscReal *a,int na,PetscTruth reset)
954: {

959:   if (na != PETSC_DECIDE && a != PETSC_NULL) {
960:     ksp->res_hist        = a;
961:     ksp->res_hist_max    = na;
962:   } else {
963:     ksp->res_hist_max    = 1000;
964:     PetscMalloc(ksp->res_hist_max*sizeof(PetscReal),&ksp->res_hist);
965:   }
966:   ksp->res_hist_len    = 0;
967:   ksp->res_hist_reset  = reset;


970:   return(0);
971: }

973: /*@C
974:    KSPGetResidualHistory - Gets the array used to hold the residual history
975:    and the number of residuals it contains.

977:    Not Collective

979:    Input Parameter:
980: .  ksp - iterative context obtained from KSPCreate()

982:    Output Parameters:
983: +  a   - pointer to array to hold history (or PETSC_NULL)
984: -  na  - number of used entries in a (or PETSC_NULL)

986:    Level: advanced

988:    Notes:
989:      Can only call after a KSPSetResidualHistory() otherwise returns 0.

991:      The Fortran version of this routine has a calling sequence
992: $   call KSPGetResidualHistory(KSP ksp, integer na, integer ierr)

994: .keywords: KSP, get, residual, history, norm

996: .seealso: KSPGetResidualHistory()

998: @*/
999: int KSPGetResidualHistory(KSP ksp,PetscReal **a,int *na)
1000: {
1003:   if (a)  *a = ksp->res_hist;
1004:   if (na) *na = ksp->res_hist_len;
1005:   return(0);
1006: }

1008: /*@C
1009:    KSPSetConvergenceTest - Sets the function to be used to determine
1010:    convergence.  

1012:    Collective on KSP

1014:    Input Parameters:
1015: +  ksp - iterative context obtained from KSPCreate()
1016: .  converge - pointer to int function
1017: -  cctx    - context for private data for the convergence routine (may be null)

1019:    Calling sequence of converge:
1020: $     converge (KSP ksp, int it, PetscReal rnorm, KSPConvergedReason *reason,void *mctx)

1022: +  ksp - iterative context obtained from KSPCreate()
1023: .  it - iteration number
1024: .  rnorm - (estimated) 2-norm of (preconditioned) residual
1025: .  reason - the reason why it has converged or diverged
1026: -  cctx  - optional convergence context, as set by KSPSetConvergenceTest()


1029:    Notes:
1030:    Must be called after the KSP type has been set so put this after
1031:    a call to KSPSetType(), or KSPSetFromOptions().

1033:    The default convergence test, KSPDefaultConverged(), aborts if the 
1034:    residual grows to more than 10000 times the initial residual.

1036:    The default is a combination of relative and absolute tolerances.  
1037:    The residual value that is tested may be an approximation; routines 
1038:    that need exact values should compute them.

1040:    Level: advanced

1042: .keywords: KSP, set, convergence, test, context

1044: .seealso: KSPDefaultConverged(), KSPGetConvergenceContext()
1045: @*/
1046: int KSPSetConvergenceTest(KSP ksp,int (*converge)(KSP,int,PetscReal,KSPConvergedReason*,void*),void *cctx)
1047: {
1050:   ksp->converged = converge;
1051:   ksp->cnvP      = (void*)cctx;
1052:   return(0);
1053: }

1055: /*@C
1056:    KSPGetConvergenceContext - Gets the convergence context set with 
1057:    KSPSetConvergenceTest().  

1059:    Not Collective

1061:    Input Parameter:
1062: .  ksp - iterative context obtained from KSPCreate()

1064:    Output Parameter:
1065: .  ctx - monitoring context

1067:    Level: advanced

1069: .keywords: KSP, get, convergence, test, context

1071: .seealso: KSPDefaultConverged(), KSPSetConvergenceTest()
1072: @*/
1073: int KSPGetConvergenceContext(KSP ksp,void **ctx)
1074: {
1077:   *ctx = ksp->cnvP;
1078:   return(0);
1079: }

1081: /*@C
1082:    KSPBuildSolution - Builds the approximate solution in a vector provided.
1083:    This routine is NOT commonly needed (see SLESSolve()).

1085:    Collective on KSP

1087:    Input Parameter:
1088: .  ctx - iterative context obtained from KSPCreate()

1090:    Output Parameter: 
1091:    Provide exactly one of
1092: +  v - location to stash solution.   
1093: -  V - the solution is returned in this location. This vector is created 
1094:        internally. This vector should NOT be destroyed by the user with
1095:        VecDestroy().

1097:    Notes:
1098:    This routine can be used in one of two ways
1099: .vb
1100:       KSPBuildSolution(ksp,PETSC_NULL,&V);
1101:    or
1102:       KSPBuildSolution(ksp,v,PETSC_NULL); 
1103: .ve
1104:    In the first case an internal vector is allocated to store the solution
1105:    (the user cannot destroy this vector). In the second case the solution
1106:    is generated in the vector that the user provides. Note that for certain 
1107:    methods, such as KSPCG, the second case requires a copy of the solution,
1108:    while in the first case the call is essentially free since it simply 
1109:    returns the vector where the solution already is stored.

1111:    Level: advanced

1113: .keywords: KSP, build, solution

1115: .seealso: KSPGetSolution(), KSPBuildResidual()
1116: @*/
1117: int KSPBuildSolution(KSP ksp,Vec v,Vec *V)
1118: {

1123:   if (!V && !v) SETERRQ(PETSC_ERR_ARG_WRONG,"Must provide either v or V");
1124:   if (!V) V = &v;
1125:   (*ksp->ops->buildsolution)(ksp,v,V);
1126:   return(0);
1127: }

1129: /*@C
1130:    KSPBuildResidual - Builds the residual in a vector provided.

1132:    Collective on KSP

1134:    Input Parameter:
1135: .  ksp - iterative context obtained from KSPCreate()

1137:    Output Parameters:
1138: +  v - optional location to stash residual.  If v is not provided,
1139:        then a location is generated.
1140: .  t - work vector.  If not provided then one is generated.
1141: -  V - the residual

1143:    Notes:
1144:    Regardless of whether or not v is provided, the residual is 
1145:    returned in V.

1147:    Level: advanced

1149: .keywords: KSP, build, residual

1151: .seealso: KSPBuildSolution()
1152: @*/
1153: int KSPBuildResidual(KSP ksp,Vec t,Vec v,Vec *V)
1154: {
1155:   int flag = 0,ierr;
1156:   Vec w = v,tt = t;

1160:   if (!w) {
1161:     VecDuplicate(ksp->vec_rhs,&w);
1162:     PetscLogObjectParent((PetscObject)ksp,w);
1163:   }
1164:   if (!tt) {
1165:     VecDuplicate(ksp->vec_rhs,&tt); flag = 1;
1166:     PetscLogObjectParent((PetscObject)ksp,tt);
1167:   }
1168:   (*ksp->ops->buildresidual)(ksp,tt,w,V);
1169:   if (flag) {VecDestroy(tt);}
1170:   return(0);
1171: }