Actual source code: linesearch.c

petsc-master 2016-04-27
Report Typos and Errors
  1: #include <petsc/private/linesearchimpl.h> /*I "petscsnes.h" I*/

  3: PetscBool         SNESLineSearchRegisterAllCalled = PETSC_FALSE;
  4: PetscFunctionList SNESLineSearchList              = NULL;

  6: PetscClassId  SNESLINESEARCH_CLASSID;
  7: PetscLogEvent SNESLineSearch_Apply;

 11: /*@
 12:    SNESLineSearchMonitorCancel - Clears all the monitor functions for a SNESLineSearch object.

 14:    Logically Collective on SNESLineSearch

 16:    Input Parameters:
 17: .  ls - the SNESLineSearch context

 19:    Options Database Key:
 20: .  -snes_linesearch_monitor_cancel - cancels all monitors that have been hardwired
 21:     into a code by calls to SNESLineSearchMonitorSet(), but does not cancel those
 22:     set via the options database

 24:    Notes:
 25:    There is no way to clear one specific monitor from a SNESLineSearch object.

 27:    This does not clear the monitor set with SNESLineSearchSetDefaultMonitor() use SNESLineSearchSetDefaultMonitor(ls,NULL) to cancel 
 28:    that one.

 30:    Level: intermediate

 32: .keywords: SNESLineSearch, nonlinear, set, monitor

 34: .seealso: SNESLineSearchMonitorDefault(), SNESLineSearchMonitorSet()
 35: @*/
 36: PetscErrorCode  SNESLineSearchMonitorCancel(SNESLineSearch ls)
 37: {
 39:   PetscInt       i;

 43:   for (i=0; i<ls->numbermonitors; i++) {
 44:     if (ls->monitordestroy[i]) {
 45:       (*ls->monitordestroy[i])(&ls->monitorcontext[i]);
 46:     }
 47:   }
 48:   ls->numbermonitors = 0;
 49:   return(0);
 50: }

 54: /*@
 55:    SNESLineSearchMonitor - runs the user provided monitor routines, if they exist

 57:    Collective on SNES

 59:    Input Parameters:
 60: .  ls - the linesearch object

 62:    Notes:
 63:    This routine is called by the SNES implementations.
 64:    It does not typically need to be called by the user.

 66:    Level: developer

 68: .seealso: SNESLineSearchMonitorSet()
 69: @*/
 70: PetscErrorCode  SNESLineSearchMonitor(SNESLineSearch ls)
 71: {
 73:   PetscInt       i,n = ls->numbermonitors;

 76:   for (i=0; i<n; i++) {
 77:     (*ls->monitorftns[i])(ls,ls->monitorcontext[i]);
 78:   }
 79:   return(0);
 80: }

 84: /*@C
 85:    SNESLineSearchMonitorSet - Sets an ADDITIONAL function that is to be used at every
 86:    iteration of the nonlinear solver to display the iteration's
 87:    progress.

 89:    Logically Collective on SNESLineSearch

 91:    Input Parameters:
 92: +  ls - the SNESLineSearch context
 93: .  f - the monitor function
 94: .  mctx - [optional] user-defined context for private data for the
 95:           monitor routine (use NULL if no context is desired)
 96: -  monitordestroy - [optional] routine that frees monitor context
 97:           (may be NULL)

 99:    Notes:
100:    Several different monitoring routines may be set by calling
101:    SNESLineSearchMonitorSet() multiple times; all will be called in the
102:    order in which they were set.

104:    Fortran notes: Only a single monitor function can be set for each SNESLineSearch object

106:    Level: intermediate

108: .keywords: SNESLineSearch, nonlinear, set, monitor

110: .seealso: SNESLineSearchMonitorDefault(), SNESLineSearchMonitorCancel()
111: @*/
112: PetscErrorCode  SNESLineSearchMonitorSet(SNESLineSearch ls,PetscErrorCode (*f)(SNESLineSearch,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
113: {
116:   if (ls->numbermonitors >= MAXSNESLSMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
117:   ls->monitorftns[ls->numbermonitors]          = f;
118:   ls->monitordestroy[ls->numbermonitors]   = monitordestroy;
119:   ls->monitorcontext[ls->numbermonitors++] = (void*)mctx;
120:   return(0);
121: }

125: /*@C
126:    SNESLineSearchMonitorSolutionUpdate - Monitors each update a new function value the linesearch tries

128:    Collective on SNESLineSearch

130:    Input Parameters:
131: +  ls - the SNES linesearch object
132: -  vf - the context for the monitor, in this case it is an ASCII PetscViewer and format

134:    Level: intermediate

136: .keywords: SNES, nonlinear, default, monitor, norm

138: .seealso: SNESMonitorSet(), SNESMonitorSolution()
139: @*/
140: PetscErrorCode  SNESLineSearchMonitorSolutionUpdate(SNESLineSearch ls,PetscViewerAndFormat *vf)
141: {
143:   PetscViewer    viewer = vf->viewer;
144:   Vec            Y,W,G;

147:   SNESLineSearchGetVecs(ls,NULL,NULL,&Y,&W,&G);
148:   PetscViewerPushFormat(viewer,vf->format);
149:   PetscViewerASCIIPrintf(viewer,"LineSearch attempted update to solution \n");
150:   VecView(Y,viewer);
151:   PetscViewerASCIIPrintf(viewer,"LineSearch attempted new solution \n");
152:   VecView(W,viewer);
153:   PetscViewerASCIIPrintf(viewer,"LineSearch attempted updated function value\n");
154:   VecView(G,viewer);
155:   PetscViewerPopFormat(viewer);
156:   return(0);
157: }

161: /*@
162:    SNESLineSearchCreate - Creates the line search context.

164:    Logically Collective on Comm

166:    Input Parameters:
167: .  comm - MPI communicator for the line search (typically from the associated SNES context).

169:    Output Parameters:
170: .  outlinesearch - the new linesearch context

172:    Level: developer

174:    Notes:
175:    The preferred calling sequence for users is to use SNESGetLineSearch() to acquire the SNESLineSearch instance
176:    already associated with the SNES.  This function is for developer use.

178: .keywords: LineSearch, create, context

180: .seealso: LineSearchDestroy(), SNESGetLineSearch()
181: @*/

183: PetscErrorCode SNESLineSearchCreate(MPI_Comm comm, SNESLineSearch *outlinesearch)
184: {
186:   SNESLineSearch linesearch;

190:   SNESInitializePackage();
191:   *outlinesearch = NULL;

193:   PetscHeaderCreate(linesearch,SNESLINESEARCH_CLASSID, "SNESLineSearch","Linesearch","SNESLineSearch",comm,SNESLineSearchDestroy,SNESLineSearchView);

195:   linesearch->vec_sol_new  = NULL;
196:   linesearch->vec_func_new = NULL;
197:   linesearch->vec_sol      = NULL;
198:   linesearch->vec_func     = NULL;
199:   linesearch->vec_update   = NULL;

201:   linesearch->lambda       = 1.0;
202:   linesearch->fnorm        = 1.0;
203:   linesearch->ynorm        = 1.0;
204:   linesearch->xnorm        = 1.0;
205:   linesearch->result       = SNES_LINESEARCH_SUCCEEDED;
206:   linesearch->norms        = PETSC_TRUE;
207:   linesearch->keeplambda   = PETSC_FALSE;
208:   linesearch->damping      = 1.0;
209:   linesearch->maxstep      = 1e8;
210:   linesearch->steptol      = 1e-12;
211:   linesearch->rtol         = 1e-8;
212:   linesearch->atol         = 1e-15;
213:   linesearch->ltol         = 1e-8;
214:   linesearch->precheckctx  = NULL;
215:   linesearch->postcheckctx = NULL;
216:   linesearch->max_its      = 1;
217:   linesearch->setupcalled  = PETSC_FALSE;
218:   *outlinesearch           = linesearch;
219:   return(0);
220: }

224: /*@
225:    SNESLineSearchSetUp - Prepares the line search for being applied by allocating
226:    any required vectors.

228:    Collective on SNESLineSearch

230:    Input Parameters:
231: .  linesearch - The LineSearch instance.

233:    Notes:
234:    For most cases, this needn't be called by users or outside of SNESLineSearchApply().
235:    The only current case where this is called outside of this is for the VI
236:    solvers, which modify the solution and work vectors before the first call
237:    of SNESLineSearchApply, requiring the SNESLineSearch work vectors to be
238:    allocated upfront.

240:    Level: advanced

242: .keywords: SNESLineSearch, SetUp

244: .seealso: SNESLineSearchReset()
245: @*/

247: PetscErrorCode SNESLineSearchSetUp(SNESLineSearch linesearch)
248: {

252:   if (!((PetscObject)linesearch)->type_name) {
253:     SNESLineSearchSetType(linesearch,SNESLINESEARCHBASIC);
254:   }
255:   if (!linesearch->setupcalled) {
256:     if (!linesearch->vec_sol_new) {
257:       VecDuplicate(linesearch->vec_sol, &linesearch->vec_sol_new);
258:     }
259:     if (!linesearch->vec_func_new) {
260:       VecDuplicate(linesearch->vec_sol, &linesearch->vec_func_new);
261:     }
262:     if (linesearch->ops->setup) {
263:       (*linesearch->ops->setup)(linesearch);
264:     }
265:     if (!linesearch->ops->snesfunc) {SNESLineSearchSetFunction(linesearch,SNESComputeFunction);}
266:     linesearch->lambda      = linesearch->damping;
267:     linesearch->setupcalled = PETSC_TRUE;
268:   }
269:   return(0);
270: }


275: /*@
276:    SNESLineSearchReset - Undoes the SNESLineSearchSetUp() and deletes any Vecs or Mats allocated by the line search.

278:    Collective on SNESLineSearch

280:    Input Parameters:
281: .  linesearch - The LineSearch instance.

283:    Notes: Usually only called by SNESReset()

285:    Level: developer

287: .keywords: SNESLineSearch, Reset

289: .seealso: SNESLineSearchSetUp()
290: @*/

292: PetscErrorCode SNESLineSearchReset(SNESLineSearch linesearch)
293: {

297:   if (linesearch->ops->reset) (*linesearch->ops->reset)(linesearch);

299:   VecDestroy(&linesearch->vec_sol_new);
300:   VecDestroy(&linesearch->vec_func_new);

302:   VecDestroyVecs(linesearch->nwork, &linesearch->work);

304:   linesearch->nwork       = 0;
305:   linesearch->setupcalled = PETSC_FALSE;
306:   return(0);
307: }

311: /*@C
312:    SNESLineSearchSetFunction - Sets the function evaluation used by the SNES line search

314:    Input Parameters:
315: .  linesearch - the SNESLineSearch context
316: +  func       - function evaluation routine

318:    Level: developer

320:    Notes: This is used internally by PETSc and not called by users

322: .keywords: get, linesearch, pre-check

324: .seealso: SNESSetFunction()
325: @*/
326: PetscErrorCode  SNESLineSearchSetFunction(SNESLineSearch linesearch, PetscErrorCode (*func)(SNES,Vec,Vec))
327: {
330:   linesearch->ops->snesfunc = func;
331:   return(0);
332: }


335: /*MC
336:     SNESLineSearchPreCheckFunction - form of function passed to check the search direction before line search is called

338:      Synopsis:
339:      #include <petscsnes.h>
340:      SNESLineSearchPreCheckFunction(SNESLineSearch snes,Vec x,Vec y, PetscBool *changed);

342:        Input Parameters:
343: +      x - solution vector
344: .      y - search direction vector
345: -      changed - flag to indicate the precheck changed x or y.

347:      Note: This is NOTE a PETSc function, rather it documents the calling sequence of functions passed to SNESLineSearchSetPreCheck()
348:            and SNESLineSearchGetPreCheck()

350:    Level: advanced

352: .seealso:   SNESLineSearchSetPreCheck(), SNESLineSearchGetPreCheck(), SNESLineSearchSetPostCheck(), SNESLineSearchGetPostCheck() 
353: M*/

357: /*@C
358:    SNESLineSearchSetPreCheck - Sets a user function that is called after the initial search direction has been computed but 
359:          before the line search routine has been applied. Allows the user to adjust the result of (usually a linear solve) that
360:          determined the search direction.

362:    Logically Collective on SNESLineSearch

364:    Input Parameters:
365: +  linesearch - the SNESLineSearch context
366: .  func - [optional] function evaluation routine, see SNESLineSearchPreCheckFunction for the calling sequence
367: -  ctx        - [optional] user-defined context for private data for the function evaluation routine (may be NULL)

369:    Level: intermediate

371: .keywords: set, linesearch, pre-check

373: .seealso: SNESLineSearchSetPostCheck(), SNESLineSearchGetPostCheck(), SNESLineSearchGetPreCheck()
374: @*/
375: PetscErrorCode  SNESLineSearchSetPreCheck(SNESLineSearch linesearch, PetscErrorCode (*func)(SNESLineSearch,Vec,Vec,PetscBool*,void*),void *ctx)
376: {
379:   if (func) linesearch->ops->precheck = func;
380:   if (ctx) linesearch->precheckctx = ctx;
381:   return(0);
382: }

386: /*@C
387:    SNESLineSearchGetPreCheck - Gets the pre-check function for the line search routine.

389:    Input Parameters:
390: .  linesearch - the SNESLineSearch context

392:    Output Parameters:
393: +  func       - [optional] function evaluation routine, see SNESLineSearchPreCheckFunction for calling sequence
394: -  ctx        - [optional] user-defined context for private data for the function evaluation routine (may be NULL)

396:    Level: intermediate

398: .keywords: get, linesearch, pre-check

400: .seealso: SNESLineSearchGetPostCheck(), SNESLineSearchSetPreCheck()
401: @*/
402: PetscErrorCode  SNESLineSearchGetPreCheck(SNESLineSearch linesearch, PetscErrorCode (**func)(SNESLineSearch,Vec,Vec,PetscBool*,void*),void **ctx)
403: {
406:   if (func) *func = linesearch->ops->precheck;
407:   if (ctx) *ctx = linesearch->precheckctx;
408:   return(0);
409: }

411: /*MC
412:     SNESLineSearchPostCheckFunction - form of function that is called after line search is complete

414:      Synopsis:
415:      #include <petscsnes.h>
416:      SNESLineSearchPostheckFunction(SNESLineSearch linesearch,Vec x,Vec y,  Vec w, *changed_y, PetscBool *changed_w);

418:      Input Parameters:
419: +      x - old solution vector
420: .      y - search direction vector
421: .      w - new solution vector
422: .      changed_y - indicates that the line search changed y
423: -      changed_w - indicates that the line search changed w

425:      Note: This is NOTE a PETSc function, rather it documents the calling sequence of functions passed to SNESLineSearchSetPostCheck()
426:            and SNESLineSearchGetPostCheck()

428:    Level: advanced

430: .seealso:   SNESLineSearchSetPreCheck(), SNESLineSearchSetPostCheck(), SNESLineSearchGetPreCheck(), SNESLineSearchGetPostCheck()
431: M*/

435: /*@C
436:    SNESLineSearchSetPostCheck - Sets a user function that is called after the line search has been applied to determine the step
437:        direction and length. Allows the user a chance to change or override the decision of the line search routine

439:    Logically Collective on SNESLineSearch

441:    Input Parameters:
442: +  linesearch - the SNESLineSearch context
443: .  func - [optional] function evaluation routine, see SNESLineSearchPostCheckFunction for the calling sequence
444: -  ctx        - [optional] user-defined context for private data for the function evaluation routine (may be NULL)

446:    Level: intermediate

448: .keywords: set, linesearch, post-check

450: .seealso: SNESLineSearchSetPreCheck()
451: @*/
452: PetscErrorCode  SNESLineSearchSetPostCheck(SNESLineSearch linesearch, PetscErrorCode (*func)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*),void *ctx)
453: {
456:   if (func) linesearch->ops->postcheck = func;
457:   if (ctx) linesearch->postcheckctx = ctx;
458:   return(0);
459: }

463: /*@C
464:    SNESLineSearchGetPostCheck - Gets the post-check function for the line search routine.

466:    Input Parameters:
467: .  linesearch - the SNESLineSearch context

469:    Output Parameters:
470: +  func - [optional] function evaluation routine, see for the calling sequence SNESLineSearchPostCheckFunction
471: -  ctx        - [optional] user-defined context for private data for the function evaluation routine (may be NULL)

473:    Level: intermediate

475: .keywords: get, linesearch, post-check

477: .seealso: SNESLineSearchGetPreCheck(), SNESLineSearchSetPostCheck()
478: @*/
479: PetscErrorCode  SNESLineSearchGetPostCheck(SNESLineSearch linesearch, PetscErrorCode (**func)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*),void **ctx)
480: {
483:   if (func) *func = linesearch->ops->postcheck;
484:   if (ctx) *ctx = linesearch->postcheckctx;
485:   return(0);
486: }

490: /*@
491:    SNESLineSearchPreCheck - Prepares the line search for being applied.

493:    Logically Collective on SNESLineSearch

495:    Input Parameters:
496: +  linesearch - The linesearch instance.
497: .  X - The current solution
498: -  Y - The step direction

500:    Output Parameters:
501: .  changed - Indicator that the precheck routine has changed anything

503:    Level: developer

505: .keywords: SNESLineSearch, Create

507: .seealso: SNESLineSearchPostCheck()
508: @*/
509: PetscErrorCode SNESLineSearchPreCheck(SNESLineSearch linesearch,Vec X,Vec Y,PetscBool *changed)
510: {

514:   *changed = PETSC_FALSE;
515:   if (linesearch->ops->precheck) {
516:     (*linesearch->ops->precheck)(linesearch, X, Y, changed, linesearch->precheckctx);
518:   }
519:   return(0);
520: }

524: /*@
525:    SNESLineSearchPostCheck - Prepares the line search for being applied.

527:    Logically Collective on SNESLineSearch

529:    Input Parameters:
530: +  linesearch - The linesearch context
531: .  X - The last solution
532: .  Y - The step direction
533: -  W - The updated solution, W = X + lambda*Y for some lambda

535:    Output Parameters:
536: +  changed_Y - Indicator if the direction Y has been changed.
537: -  changed_W - Indicator if the new candidate solution W has been changed.

539:    Level: developer

541: .keywords: SNESLineSearch, Create

543: .seealso: SNESLineSearchPreCheck()
544: @*/
545: PetscErrorCode SNESLineSearchPostCheck(SNESLineSearch linesearch,Vec X,Vec Y,Vec W,PetscBool *changed_Y,PetscBool *changed_W)
546: {

550:   *changed_Y = PETSC_FALSE;
551:   *changed_W = PETSC_FALSE;
552:   if (linesearch->ops->postcheck) {
553:     (*linesearch->ops->postcheck)(linesearch,X,Y,W,changed_Y,changed_W,linesearch->postcheckctx);
556:   }
557:   return(0);
558: }

562: /*@C
563:    SNESLineSearchPreCheckPicard - Implements a correction that is sometimes useful to improve the convergence rate of Picard iteration

565:    Logically Collective on SNESLineSearch

567:    Input Arguments:
568: +  linesearch - linesearch context
569: .  X - base state for this step
570: .  Y - initial correction
571: -  ctx - context for this function

573:    Output Arguments:
574: +  Y - correction, possibly modified
575: -  changed - flag indicating that Y was modified

577:    Options Database Key:
578: +  -snes_linesearch_precheck_picard - activate this routine
579: -  -snes_linesearch_precheck_picard_angle - angle

581:    Level: advanced

583:    Notes:
584:    This function should be passed to SNESLineSearchSetPreCheck()

586:    The justification for this method involves the linear convergence of a Picard iteration
587:    so the Picard linearization should be provided in place of the "Jacobian". This correction
588:    is generally not useful when using a Newton linearization.

590:    Reference:
591:    Hindmarsh and Payne (1996) Time step limits for stable solutions of the ice sheet equation, Annals of Glaciology.

593: .seealso: SNESLineSearchSetPreCheck()
594: @*/
595: PetscErrorCode SNESLineSearchPreCheckPicard(SNESLineSearch linesearch,Vec X,Vec Y,PetscBool *changed,void *ctx)
596: {
598:   PetscReal      angle = *(PetscReal*)linesearch->precheckctx;
599:   Vec            Ylast;
600:   PetscScalar    dot;
601:   PetscInt       iter;
602:   PetscReal      ynorm,ylastnorm,theta,angle_radians;
603:   SNES           snes;

606:   SNESLineSearchGetSNES(linesearch, &snes);
607:   PetscObjectQuery((PetscObject)snes,"SNESLineSearchPreCheckPicard_Ylast",(PetscObject*)&Ylast);
608:   if (!Ylast) {
609:     VecDuplicate(Y,&Ylast);
610:     PetscObjectCompose((PetscObject)snes,"SNESLineSearchPreCheckPicard_Ylast",(PetscObject)Ylast);
611:     PetscObjectDereference((PetscObject)Ylast);
612:   }
613:   SNESGetIterationNumber(snes,&iter);
614:   if (iter < 2) {
615:     VecCopy(Y,Ylast);
616:     *changed = PETSC_FALSE;
617:     return(0);
618:   }

620:   VecDot(Y,Ylast,&dot);
621:   VecNorm(Y,NORM_2,&ynorm);
622:   VecNorm(Ylast,NORM_2,&ylastnorm);
623:   /* Compute the angle between the vectors Y and Ylast, clip to keep inside the domain of acos() */
624:   theta         = PetscAcosReal((PetscReal)PetscClipInterval(PetscAbsScalar(dot) / (ynorm * ylastnorm),-1.0,1.0));
625:   angle_radians = angle * PETSC_PI / 180.;
626:   if (PetscAbsReal(theta) < angle_radians || PetscAbsReal(theta - PETSC_PI) < angle_radians) {
627:     /* Modify the step Y */
628:     PetscReal alpha,ydiffnorm;
629:     VecAXPY(Ylast,-1.0,Y);
630:     VecNorm(Ylast,NORM_2,&ydiffnorm);
631:     alpha = ylastnorm / ydiffnorm;
632:     VecCopy(Y,Ylast);
633:     VecScale(Y,alpha);
634:     PetscInfo3(snes,"Angle %14.12e degrees less than threshold %14.12e, corrected step by alpha=%14.12e\n",(double)(theta*180./PETSC_PI),(double)angle,(double)alpha);
635:   } else {
636:     PetscInfo2(snes,"Angle %14.12e degrees exceeds threshold %14.12e, no correction applied\n",(double)(theta*180./PETSC_PI),(double)angle);
637:     VecCopy(Y,Ylast);
638:     *changed = PETSC_FALSE;
639:   }
640:   return(0);
641: }

645: /*@
646:    SNESLineSearchApply - Computes the line-search update.

648:    Collective on SNESLineSearch

650:    Input Parameters:
651: +  linesearch - The linesearch context
652: .  X - The current solution
653: .  F - The current function
654: .  fnorm - The current norm
655: -  Y - The search direction

657:    Output Parameters:
658: +  X - The new solution
659: .  F - The new function
660: -  fnorm - The new function norm

662:    Options Database Keys:
663: + -snes_linesearch_type - basic, bt, l2, cp, nleqerr, shell
664: . -snes_linesearch_monitor [:filename] - Print progress of line searches
665: . -snes_linesearch_damping - The linesearch damping parameter
666: . -snes_linesearch_norms   - Turn on/off the linesearch norms
667: . -snes_linesearch_keeplambda - Keep the previous search length as the initial guess
668: - -snes_linesearch_max_it - The number of iterations for iterative line searches

670:    Notes:
671:    This is typically called from within a SNESSolve() implementation in order to
672:    help with convergence of the nonlinear method.  Various SNES types use line searches
673:    in different ways, but the overarching theme is that a line search is used to determine
674:    an optimal damping parameter of a step at each iteration of the method.  Each
675:    application of the line search may invoke SNESComputeFunction several times, and
676:    therefore may be fairly expensive.

678:    Level: Intermediate

680: .keywords: SNESLineSearch, Create

682: .seealso: SNESLineSearchCreate(), SNESLineSearchPreCheck(), SNESLineSearchPostCheck(), SNESSolve(), SNESComputeFunction()
683: @*/
684: PetscErrorCode SNESLineSearchApply(SNESLineSearch linesearch, Vec X, Vec F, PetscReal * fnorm, Vec Y)
685: {


694:   linesearch->result = SNES_LINESEARCH_SUCCEEDED;

696:   linesearch->vec_sol    = X;
697:   linesearch->vec_update = Y;
698:   linesearch->vec_func   = F;

700:   SNESLineSearchSetUp(linesearch);

702:   if (!linesearch->keeplambda) linesearch->lambda = linesearch->damping; /* set the initial guess to lambda */

704:   if (fnorm) linesearch->fnorm = *fnorm;
705:   else {
706:     VecNorm(F, NORM_2, &linesearch->fnorm);
707:   }

709:   PetscLogEventBegin(SNESLineSearch_Apply,linesearch,X,F,Y);

711:   (*linesearch->ops->apply)(linesearch);

713:   PetscLogEventEnd(SNESLineSearch_Apply,linesearch,X,F,Y);

715:   if (fnorm) *fnorm = linesearch->fnorm;
716:   return(0);
717: }

721: /*@
722:    SNESLineSearchDestroy - Destroys the line search instance.

724:    Collective on SNESLineSearch

726:    Input Parameters:
727: .  linesearch - The linesearch context

729:    Level: Intermediate

731: .keywords: SNESLineSearch, Destroy

733: .seealso: SNESLineSearchCreate(), SNESLineSearchReset(), SNESDestroy()
734: @*/
735: PetscErrorCode SNESLineSearchDestroy(SNESLineSearch * linesearch)
736: {

740:   if (!*linesearch) return(0);
742:   if (--((PetscObject)(*linesearch))->refct > 0) {*linesearch = 0; return(0);}
743:   PetscObjectSAWsViewOff((PetscObject)*linesearch);
744:   SNESLineSearchReset(*linesearch);
745:   if ((*linesearch)->ops->destroy) (*linesearch)->ops->destroy(*linesearch);
746:   PetscViewerDestroy(&(*linesearch)->monitor);
747:   SNESLineSearchMonitorCancel((*linesearch));
748:   PetscHeaderDestroy(linesearch);
749:   return(0);
750: }

754: /*@
755:    SNESLineSearchSetDefaultMonitor - Turns on/off printing useful information and debugging output about the line search.

757:    Input Parameters:
758: +  linesearch - the linesearch object
759: -  viewer - an ASCII PetscViewer or NULL to turn off monitor

761:    Logically Collective on SNESLineSearch

763:    Options Database:
764: .   -snes_linesearch_monitor [:filename] - enables the monitor

766:    Level: intermediate

768:    Developer Note: This monitor is implemented differently than the other SNESLineSearchMonitors that are set with 
769:      SNESLineSearchMonitorSet() since it is called in many locations of the line search routines to display aspects of the 
770:      line search that are not visible to the other monitors.

772: .seealso: SNESLineSearchGetDefaultMonitor(), PetscViewer, SNESLineSearchSetMonitor()
773: @*/
774: PetscErrorCode  SNESLineSearchSetDefaultMonitor(SNESLineSearch linesearch, PetscViewer viewer)
775: {

779:   if (viewer) {PetscObjectReference((PetscObject)viewer);}
780:   PetscViewerDestroy(&linesearch->monitor);
781:   linesearch->monitor = viewer;
782:   return(0);
783: }

787: /*@
788:    SNESLineSearchGetDefaultMonitor - Gets the PetscViewer instance for the line search monitor.

790:    Input Parameter:
791: .  linesearch - linesearch context

793:    Output Parameter:
794: .  monitor - monitor context

796:    Logically Collective on SNES

798:    Options Database Keys:
799: .   -snes_linesearch_monitor - enables the monitor

801:    Level: intermediate

803: .seealso: SNESLineSearchSetDefaultMonitor(), PetscViewer
804: @*/
805: PetscErrorCode  SNESLineSearchGetDefaultMonitor(SNESLineSearch linesearch, PetscViewer *monitor)
806: {
809:   if (monitor) {
811:     *monitor = linesearch->monitor;
812:   }
813:   return(0);
814: }

818: /*@C
819:    SNESLineSearchMonitorSetFromOptions - Sets a monitor function and viewer appropriate for the type indicated by the user

821:    Collective on SNESLineSearch

823:    Input Parameters:
824: +  ls - LineSearch object you wish to monitor
825: .  name - the monitor type one is seeking
826: .  help - message indicating what monitoring is done
827: .  manual - manual page for the monitor
828: .  monitor - the monitor function
829: -  monitorsetup - a function that is called once ONLY if the user selected this monitor that may set additional features of the SNESLineSearch or PetscViewer objects

831:    Level: developer

833: .seealso: PetscOptionsGetViewer(), PetscOptionsGetReal(), PetscOptionsHasName(), PetscOptionsGetString(),
834:           PetscOptionsGetIntArray(), PetscOptionsGetRealArray(), PetscOptionsBool()
835:           PetscOptionsInt(), PetscOptionsString(), PetscOptionsReal(), PetscOptionsBool(),
836:           PetscOptionsName(), PetscOptionsBegin(), PetscOptionsEnd(), PetscOptionsHead(),
837:           PetscOptionsStringArray(),PetscOptionsRealArray(), PetscOptionsScalar(),
838:           PetscOptionsBoolGroupBegin(), PetscOptionsBoolGroup(), PetscOptionsBoolGroupEnd(),
839:           PetscOptionsFList(), PetscOptionsEList()
840: @*/
841: PetscErrorCode  SNESLineSearchMonitorSetFromOptions(SNESLineSearch ls,const char name[],const char help[], const char manual[],PetscErrorCode (*monitor)(SNESLineSearch,PetscViewerAndFormat*),PetscErrorCode (*monitorsetup)(SNESLineSearch,PetscViewerAndFormat*))
842: {
843:   PetscErrorCode    ierr;
844:   PetscViewer       viewer;
845:   PetscViewerFormat format;
846:   PetscBool         flg;

849:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)ls),((PetscObject)ls)->prefix,name,&viewer,&format,&flg);
850:   if (flg) {
851:     PetscViewerAndFormat *vf;
852:     PetscViewerAndFormatCreate(viewer,format,&vf);
853:     PetscObjectDereference((PetscObject)viewer);
854:     if (monitorsetup) {
855:       (*monitorsetup)(ls,vf);
856:     }
857:     SNESLineSearchMonitorSet(ls,(PetscErrorCode (*)(SNESLineSearch,void*))monitor,vf,(PetscErrorCode (*)(void**))PetscViewerAndFormatDestroy);
858:   }
859:   return(0);
860: }

864: /*@
865:    SNESLineSearchSetFromOptions - Sets options for the line search

867:    Input Parameters:
868: .  linesearch - linesearch context

870:    Options Database Keys:
871: + -snes_linesearch_type <type> - basic, bt, l2, cp, nleqerr, shell
872: . -snes_linesearch_order <order> - 1, 2, 3.  Most types only support certain orders (bt supports 2 or 3)
873: . -snes_linesearch_norms   - Turn on/off the linesearch norms for the basic linesearch type
874: . -snes_linesearch_minlambda - The minimum step length
875: . -snes_linesearch_maxstep - The maximum step size
876: . -snes_linesearch_rtol - Relative tolerance for iterative line searches
877: . -snes_linesearch_atol - Absolute tolerance for iterative line searches
878: . -snes_linesearch_ltol - Change in lambda tolerance for iterative line searches
879: . -snes_linesearch_max_it - The number of iterations for iterative line searches
880: . -snes_linesearch_monitor [:filename] - Print progress of line searches
881: . -snes_linesearch_monitor_solution_update [viewer:filename:format] - view each update tried by line search routine
882: . -snes_linesearch_damping - The linesearch damping parameter
883: . -snes_linesearch_keeplambda - Keep the previous search length as the initial guess.
884: . -snes_linesearch_precheck_picard - Use precheck that speeds up convergence of picard method
885: - -snes_linesearch_precheck_picard_angle - Angle used in picard precheck method

887:    Logically Collective on SNESLineSearch

889:    Level: intermediate

891: .seealso: SNESLineSearchCreate(), SNESLineSearchSetOrder(), SNESLineSearchSetType(), SNESLineSearchSetTolerances(), SNESLineSearchSetDamping(), SNESLineSearchPreCheckPicard()
892: @*/
893: PetscErrorCode SNESLineSearchSetFromOptions(SNESLineSearch linesearch)
894: {
895:   PetscErrorCode    ierr;
896:   const char        *deft = SNESLINESEARCHBASIC;
897:   char              type[256];
898:   PetscBool         flg, set;
899:   PetscViewer       viewer;

902:   SNESLineSearchRegisterAll();

904:   PetscObjectOptionsBegin((PetscObject)linesearch);
905:   if (((PetscObject)linesearch)->type_name) deft = ((PetscObject)linesearch)->type_name;
906:   PetscOptionsFList("-snes_linesearch_type","Linesearch type","SNESLineSearchSetType",SNESLineSearchList,deft,type,256,&flg);
907:   if (flg) {
908:     SNESLineSearchSetType(linesearch,type);
909:   } else if (!((PetscObject)linesearch)->type_name) {
910:     SNESLineSearchSetType(linesearch,deft);
911:   }

913:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)linesearch),((PetscObject)linesearch)->prefix,"-snes_linesearch_monitor",&viewer,NULL,&set);
914:   if (set) {
915:     SNESLineSearchSetDefaultMonitor(linesearch,viewer);
916:     PetscViewerDestroy(&viewer);
917:   }
918:   SNESLineSearchMonitorSetFromOptions(linesearch,"-snes_linesearch_monitor_solution_update","View correction at each iteration","SNESLineSearchMonitorSolutionUpdate",SNESLineSearchMonitorSolutionUpdate,NULL);
919: 
920:   /* tolerances */
921:   PetscOptionsReal("-snes_linesearch_minlambda","Minimum step length","SNESLineSearchSetTolerances",linesearch->steptol,&linesearch->steptol,NULL);
922:   PetscOptionsReal("-snes_linesearch_maxstep","Maximum step size","SNESLineSearchSetTolerances",linesearch->maxstep,&linesearch->maxstep,NULL);
923:   PetscOptionsReal("-snes_linesearch_rtol","Relative tolerance for iterative line search","SNESLineSearchSetTolerances",linesearch->rtol,&linesearch->rtol,NULL);
924:   PetscOptionsReal("-snes_linesearch_atol","Absolute tolerance for iterative line search","SNESLineSearchSetTolerances",linesearch->atol,&linesearch->atol,NULL);
925:   PetscOptionsReal("-snes_linesearch_ltol","Change in lambda tolerance for iterative line search","SNESLineSearchSetTolerances",linesearch->ltol,&linesearch->ltol,NULL);
926:   PetscOptionsInt("-snes_linesearch_max_it","Maximum iterations for iterative line searches","SNESLineSearchSetTolerances",linesearch->max_its,&linesearch->max_its,NULL);

928:   /* damping parameters */
929:   PetscOptionsReal("-snes_linesearch_damping","Line search damping and initial step guess","SNESLineSearchSetDamping",linesearch->damping,&linesearch->damping,NULL);

931:   PetscOptionsBool("-snes_linesearch_keeplambda","Use previous lambda as damping","SNESLineSearchSetKeepLambda",linesearch->keeplambda,&linesearch->keeplambda,NULL);

933:   /* precheck */
934:   PetscOptionsBool("-snes_linesearch_precheck_picard","Use a correction that sometimes improves convergence of Picard iteration","SNESLineSearchPreCheckPicard",flg,&flg,&set);
935:   if (set) {
936:     if (flg) {
937:       linesearch->precheck_picard_angle = 10.; /* correction only active if angle is less than 10 degrees */

939:       PetscOptionsReal("-snes_linesearch_precheck_picard_angle","Maximum angle at which to activate the correction",
940:                               "none",linesearch->precheck_picard_angle,&linesearch->precheck_picard_angle,NULL);
941:       SNESLineSearchSetPreCheck(linesearch,SNESLineSearchPreCheckPicard,&linesearch->precheck_picard_angle);
942:     } else {
943:       SNESLineSearchSetPreCheck(linesearch,NULL,NULL);
944:     }
945:   }
946:   PetscOptionsInt("-snes_linesearch_order","Order of approximation used in the line search","SNESLineSearchSetOrder",linesearch->order,&linesearch->order,NULL);
947:   PetscOptionsBool("-snes_linesearch_norms","Compute final norms in line search","SNESLineSearchSetComputeNorms",linesearch->norms,&linesearch->norms,NULL);

949:   if (linesearch->ops->setfromoptions) {
950:     (*linesearch->ops->setfromoptions)(PetscOptionsObject,linesearch);
951:   }

953:   PetscObjectProcessOptionsHandlers(PetscOptionsObject,(PetscObject)linesearch);
954:   PetscOptionsEnd();
955:   return(0);
956: }

960: /*@
961:    SNESLineSearchView - Prints useful information about the line search

963:    Input Parameters:
964: .  linesearch - linesearch context

966:    Logically Collective on SNESLineSearch

968:    Level: intermediate

970: .seealso: SNESLineSearchCreate()
971: @*/
972: PetscErrorCode SNESLineSearchView(SNESLineSearch linesearch, PetscViewer viewer)
973: {
975:   PetscBool      iascii;

979:   if (!viewer) {
980:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)linesearch),&viewer);
981:   }

985:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
986:   if (iascii) {
987:     PetscObjectPrintClassNamePrefixType((PetscObject)linesearch,viewer);
988:     if (linesearch->ops->view) {
989:       PetscViewerASCIIPushTab(viewer);
990:       (*linesearch->ops->view)(linesearch,viewer);
991:       PetscViewerASCIIPopTab(viewer);
992:     }
993:     PetscViewerASCIIPrintf(viewer,"  maxstep=%e, minlambda=%e\n", (double)linesearch->maxstep,(double)linesearch->steptol);
994:     PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%e, absolute=%e, lambda=%e\n", (double)linesearch->rtol,(double)linesearch->atol,(double)linesearch->ltol);
995:     PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D\n", linesearch->max_its);
996:     if (linesearch->ops->precheck) {
997:       if (linesearch->ops->precheck == SNESLineSearchPreCheckPicard) {
998:         PetscViewerASCIIPrintf(viewer,"  using precheck step to speed up Picard convergence\n", linesearch->max_its);
999:       } else {
1000:         PetscViewerASCIIPrintf(viewer,"  using user-defined precheck step\n", linesearch->max_its);
1001:       }
1002:     }
1003:     if (linesearch->ops->postcheck) {
1004:       PetscViewerASCIIPrintf(viewer,"  using user-defined postcheck step\n", linesearch->max_its);
1005:     }
1006:   }
1007:   return(0);
1008: }

1012: /*@C
1013:    SNESLineSearchSetType - Sets the linesearch type

1015:    Logically Collective on SNESLineSearch

1017:    Input Parameters:
1018: +  linesearch - linesearch context
1019: -  type - The type of line search to be used

1021:    Available Types:
1022: +  basic - Simple damping line search.
1023: .  bt - Backtracking line search over the L2 norm of the function
1024: .  l2 - Secant line search over the L2 norm of the function
1025: .  cp - Critical point secant line search assuming F(x) = grad G(x) for some unknown G(x)
1026: .  nleqerr - Affine-covariant error-oriented linesearch
1027: -  shell - User provided SNESLineSearch implementation

1029:    Level: intermediate

1031: .seealso: SNESLineSearchCreate()
1032: @*/
1033: PetscErrorCode SNESLineSearchSetType(SNESLineSearch linesearch, SNESLineSearchType type)
1034: {
1035:   PetscErrorCode ierr,(*r)(SNESLineSearch);
1036:   PetscBool      match;


1042:   PetscObjectTypeCompare((PetscObject)linesearch,type,&match);
1043:   if (match) return(0);

1045:   PetscFunctionListFind(SNESLineSearchList,type,&r);
1046:   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested Line Search type %s",type);
1047:   /* Destroy the previous private linesearch context */
1048:   if (linesearch->ops->destroy) {
1049:     (*(linesearch)->ops->destroy)(linesearch);

1051:     linesearch->ops->destroy = NULL;
1052:   }
1053:   /* Reinitialize function pointers in SNESLineSearchOps structure */
1054:   linesearch->ops->apply          = 0;
1055:   linesearch->ops->view           = 0;
1056:   linesearch->ops->setfromoptions = 0;
1057:   linesearch->ops->destroy        = 0;

1059:   PetscObjectChangeTypeName((PetscObject)linesearch,type);
1060:   (*r)(linesearch);
1061:   return(0);
1062: }

1066: /*@
1067:    SNESLineSearchSetSNES - Sets the SNES for the linesearch for function evaluation.

1069:    Input Parameters:
1070: +  linesearch - linesearch context
1071: -  snes - The snes instance

1073:    Level: developer

1075:    Notes:
1076:    This happens automatically when the line search is obtained/created with
1077:    SNESGetLineSearch().  This routine is therefore mainly called within SNES
1078:    implementations.

1080:    Level: developer

1082: .seealso: SNESLineSearchGetSNES(), SNESLineSearchSetVecs(), SNES
1083: @*/
1084: PetscErrorCode  SNESLineSearchSetSNES(SNESLineSearch linesearch, SNES snes)
1085: {
1089:   linesearch->snes = snes;
1090:   return(0);
1091: }

1095: /*@
1096:    SNESLineSearchGetSNES - Gets the SNES instance associated with the line search.
1097:    Having an associated SNES is necessary because most line search implementations must be able to
1098:    evaluate the function using SNESComputeFunction() for the associated SNES.  This routine
1099:    is used in the line search implementations when one must get this associated SNES instance.

1101:    Input Parameters:
1102: .  linesearch - linesearch context

1104:    Output Parameters:
1105: .  snes - The snes instance

1107:    Level: developer

1109: .seealso: SNESLineSearchGetSNES(), SNESLineSearchSetVecs(), SNES
1110: @*/
1111: PetscErrorCode  SNESLineSearchGetSNES(SNESLineSearch linesearch, SNES *snes)
1112: {
1116:   *snes = linesearch->snes;
1117:   return(0);
1118: }

1122: /*@
1123:    SNESLineSearchGetLambda - Gets the last linesearch steplength discovered.

1125:    Input Parameters:
1126: .  linesearch - linesearch context

1128:    Output Parameters:
1129: .  lambda - The last steplength computed during SNESLineSearchApply()

1131:    Level: advanced

1133:    Notes:
1134:    This is useful in methods where the solver is ill-scaled and
1135:    requires some adaptive notion of the difference in scale between the
1136:    solution and the function.  For instance, SNESQN may be scaled by the
1137:    line search lambda using the argument -snes_qn_scaling ls.

1139: .seealso: SNESLineSearchSetLambda(), SNESLineSearchGetDamping(), SNESLineSearchApply()
1140: @*/
1141: PetscErrorCode  SNESLineSearchGetLambda(SNESLineSearch linesearch,PetscReal *lambda)
1142: {
1146:   *lambda = linesearch->lambda;
1147:   return(0);
1148: }

1152: /*@
1153:    SNESLineSearchSetLambda - Sets the linesearch steplength.

1155:    Input Parameters:
1156: +  linesearch - linesearch context
1157: -  lambda - The last steplength.

1159:    Notes:
1160:    This routine is typically used within implementations of SNESLineSearchApply()
1161:    to set the final steplength.  This routine (and SNESLineSearchGetLambda()) were
1162:    added in order to facilitate Quasi-Newton methods that use the previous steplength
1163:    as an inner scaling parameter.

1165:    Level: advanced

1167: .seealso: SNESLineSearchGetLambda()
1168: @*/
1169: PetscErrorCode  SNESLineSearchSetLambda(SNESLineSearch linesearch, PetscReal lambda)
1170: {
1173:   linesearch->lambda = lambda;
1174:   return(0);
1175: }

1177: #undef  __FUNCT__
1179: /*@
1180:    SNESLineSearchGetTolerances - Gets the tolerances for the linesearch.  These include
1181:    tolerances for the relative and absolute change in the function norm, the change
1182:    in lambda for iterative line searches, the minimum steplength, the maximum steplength,
1183:    and the maximum number of iterations the line search procedure may take.

1185:    Input Parameters:
1186: .  linesearch - linesearch context

1188:    Output Parameters:
1189: +  steptol - The minimum steplength
1190: .  maxstep - The maximum steplength
1191: .  rtol    - The relative tolerance for iterative line searches
1192: .  atol    - The absolute tolerance for iterative line searches
1193: .  ltol    - The change in lambda tolerance for iterative line searches
1194: -  max_it  - The maximum number of iterations of the line search

1196:    Level: intermediate

1198:    Notes:
1199:    Different line searches may implement these parameters slightly differently as
1200:    the type requires.

1202: .seealso: SNESLineSearchSetTolerances()
1203: @*/
1204: PetscErrorCode  SNESLineSearchGetTolerances(SNESLineSearch linesearch,PetscReal *steptol,PetscReal *maxstep, PetscReal *rtol, PetscReal *atol, PetscReal *ltol, PetscInt *max_its)
1205: {
1208:   if (steptol) {
1210:     *steptol = linesearch->steptol;
1211:   }
1212:   if (maxstep) {
1214:     *maxstep = linesearch->maxstep;
1215:   }
1216:   if (rtol) {
1218:     *rtol = linesearch->rtol;
1219:   }
1220:   if (atol) {
1222:     *atol = linesearch->atol;
1223:   }
1224:   if (ltol) {
1226:     *ltol = linesearch->ltol;
1227:   }
1228:   if (max_its) {
1230:     *max_its = linesearch->max_its;
1231:   }
1232:   return(0);
1233: }

1235: #undef  __FUNCT__
1237: /*@
1238:    SNESLineSearchSetTolerances -  Gets the tolerances for the linesearch.  These include
1239:    tolerances for the relative and absolute change in the function norm, the change
1240:    in lambda for iterative line searches, the minimum steplength, the maximum steplength,
1241:    and the maximum number of iterations the line search procedure may take.

1243:    Input Parameters:
1244: +  linesearch - linesearch context
1245: .  steptol - The minimum steplength
1246: .  maxstep - The maximum steplength
1247: .  rtol    - The relative tolerance for iterative line searches
1248: .  atol    - The absolute tolerance for iterative line searches
1249: .  ltol    - The change in lambda tolerance for iterative line searches
1250: -  max_it  - The maximum number of iterations of the line search

1252:    Notes:
1253:    The user may choose to not set any of the tolerances using PETSC_DEFAULT in
1254:    place of an argument.

1256:    Level: intermediate

1258: .seealso: SNESLineSearchGetTolerances()
1259: @*/
1260: PetscErrorCode  SNESLineSearchSetTolerances(SNESLineSearch linesearch,PetscReal steptol,PetscReal maxstep, PetscReal rtol, PetscReal atol, PetscReal ltol, PetscInt max_its)
1261: {

1271:   if (steptol!= PETSC_DEFAULT) {
1272:     if (steptol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Minimum step length %14.12e must be non-negative",(double)steptol);
1273:     linesearch->steptol = steptol;
1274:   }

1276:   if (maxstep!= PETSC_DEFAULT) {
1277:     if (maxstep < 0.0) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Maximum step length %14.12e must be non-negative",(double)maxstep);
1278:     linesearch->maxstep = maxstep;
1279:   }

1281:   if (rtol != PETSC_DEFAULT) {
1282:     if (rtol < 0.0 || 1.0 <= rtol) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Relative tolerance %14.12e must be non-negative and less than 1.0",(double)rtol);
1283:     linesearch->rtol = rtol;
1284:   }

1286:   if (atol != PETSC_DEFAULT) {
1287:     if (atol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %14.12e must be non-negative",(double)atol);
1288:     linesearch->atol = atol;
1289:   }

1291:   if (ltol != PETSC_DEFAULT) {
1292:     if (ltol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Labmda tolerance %14.12e must be non-negative",(double)ltol);
1293:     linesearch->ltol = ltol;
1294:   }

1296:   if (max_its != PETSC_DEFAULT) {
1297:     if (max_its < 0) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",max_its);
1298:     linesearch->max_its = max_its;
1299:   }
1300:   return(0);
1301: }

1305: /*@
1306:    SNESLineSearchGetDamping - Gets the line search damping parameter.

1308:    Input Parameters:
1309: .  linesearch - linesearch context

1311:    Output Parameters:
1312: .  damping - The damping parameter

1314:    Level: advanced

1316: .seealso: SNESLineSearchGetStepTolerance(), SNESQN
1317: @*/

1319: PetscErrorCode  SNESLineSearchGetDamping(SNESLineSearch linesearch,PetscReal *damping)
1320: {
1324:   *damping = linesearch->damping;
1325:   return(0);
1326: }

1330: /*@
1331:    SNESLineSearchSetDamping - Sets the line search damping paramter.

1333:    Input Parameters:
1334: +  linesearch - linesearch context
1335: -  damping - The damping parameter

1337:    Options Database:
1338: .   -snes_linesearch_damping
1339:    Level: intermediate

1341:    Notes:
1342:    The basic line search merely takes the update step scaled by the damping parameter.
1343:    The use of the damping parameter in the l2 and cp line searches is much more subtle;
1344:    it is used as a starting point in calculating the secant step. However, the eventual
1345:    step may be of greater length than the damping parameter.  In the bt line search it is
1346:    used as the maximum possible step length, as the bt line search only backtracks.

1348: .seealso: SNESLineSearchGetDamping()
1349: @*/
1350: PetscErrorCode  SNESLineSearchSetDamping(SNESLineSearch linesearch,PetscReal damping)
1351: {
1354:   linesearch->damping = damping;
1355:   return(0);
1356: }

1360: /*@
1361:    SNESLineSearchGetOrder - Gets the line search approximation order.

1363:    Input Parameters:
1364: .  linesearch - linesearch context

1366:    Output Parameters:
1367: .  order - The order

1369:    Possible Values for order:
1370: +  1 or SNES_LINESEARCH_ORDER_LINEAR - linear order
1371: .  2 or SNES_LINESEARCH_ORDER_QUADRATIC - quadratic order
1372: -  3 or SNES_LINESEARCH_ORDER_CUBIC - cubic order

1374:    Level: intermediate

1376: .seealso: SNESLineSearchSetOrder()
1377: @*/

1379: PetscErrorCode  SNESLineSearchGetOrder(SNESLineSearch linesearch,PetscInt *order)
1380: {
1384:   *order = linesearch->order;
1385:   return(0);
1386: }

1390: /*@
1391:    SNESLineSearchSetOrder - Sets the line search damping paramter.

1393:    Input Parameters:
1394: .  linesearch - linesearch context
1395: .  order - The damping parameter

1397:    Level: intermediate

1399:    Possible Values for order:
1400: +  1 or SNES_LINESEARCH_ORDER_LINEAR - linear order
1401: .  2 or SNES_LINESEARCH_ORDER_QUADRATIC - quadratic order
1402: -  3 or SNES_LINESEARCH_ORDER_CUBIC - cubic order

1404:    Notes:
1405:    Variable orders are supported by the following line searches:
1406: +  bt - cubic and quadratic
1407: -  cp - linear and quadratic

1409: .seealso: SNESLineSearchGetOrder()
1410: @*/
1411: PetscErrorCode  SNESLineSearchSetOrder(SNESLineSearch linesearch,PetscInt order)
1412: {
1415:   linesearch->order = order;
1416:   return(0);
1417: }

1421: /*@
1422:    SNESLineSearchGetNorms - Gets the norms for for X, Y, and F.

1424:    Input Parameters:
1425: .  linesearch - linesearch context

1427:    Output Parameters:
1428: +  xnorm - The norm of the current solution
1429: .  fnorm - The norm of the current function
1430: -  ynorm - The norm of the current update

1432:    Notes:
1433:    This function is mainly called from SNES implementations.

1435:    Level: developer

1437: .seealso: SNESLineSearchSetNorms() SNESLineSearchGetVecs()
1438: @*/
1439: PetscErrorCode  SNESLineSearchGetNorms(SNESLineSearch linesearch, PetscReal * xnorm, PetscReal * fnorm, PetscReal * ynorm)
1440: {
1443:   if (xnorm) *xnorm = linesearch->xnorm;
1444:   if (fnorm) *fnorm = linesearch->fnorm;
1445:   if (ynorm) *ynorm = linesearch->ynorm;
1446:   return(0);
1447: }

1451: /*@
1452:    SNESLineSearchSetNorms - Gets the computed norms for for X, Y, and F.

1454:    Input Parameters:
1455: +  linesearch - linesearch context
1456: .  xnorm - The norm of the current solution
1457: .  fnorm - The norm of the current function
1458: -  ynorm - The norm of the current update

1460:    Level: advanced

1462: .seealso: SNESLineSearchGetNorms(), SNESLineSearchSetVecs()
1463: @*/
1464: PetscErrorCode  SNESLineSearchSetNorms(SNESLineSearch linesearch, PetscReal xnorm, PetscReal fnorm, PetscReal ynorm)
1465: {
1468:   linesearch->xnorm = xnorm;
1469:   linesearch->fnorm = fnorm;
1470:   linesearch->ynorm = ynorm;
1471:   return(0);
1472: }

1476: /*@
1477:    SNESLineSearchComputeNorms - Computes the norms of X, F, and Y.

1479:    Input Parameters:
1480: .  linesearch - linesearch context

1482:    Options Database Keys:
1483: .   -snes_linesearch_norms - turn norm computation on or off

1485:    Level: intermediate

1487: .seealso: SNESLineSearchGetNorms, SNESLineSearchSetNorms(), SNESLineSearchSetComputeNorms()
1488: @*/
1489: PetscErrorCode SNESLineSearchComputeNorms(SNESLineSearch linesearch)
1490: {
1492:   SNES           snes;

1495:   if (linesearch->norms) {
1496:     if (linesearch->ops->vinorm) {
1497:       SNESLineSearchGetSNES(linesearch, &snes);
1498:       VecNorm(linesearch->vec_sol, NORM_2, &linesearch->xnorm);
1499:       VecNorm(linesearch->vec_update, NORM_2, &linesearch->ynorm);
1500:       (*linesearch->ops->vinorm)(snes, linesearch->vec_func, linesearch->vec_sol, &linesearch->fnorm);
1501:     } else {
1502:       VecNormBegin(linesearch->vec_func,   NORM_2, &linesearch->fnorm);
1503:       VecNormBegin(linesearch->vec_sol,    NORM_2, &linesearch->xnorm);
1504:       VecNormBegin(linesearch->vec_update, NORM_2, &linesearch->ynorm);
1505:       VecNormEnd(linesearch->vec_func,     NORM_2, &linesearch->fnorm);
1506:       VecNormEnd(linesearch->vec_sol,      NORM_2, &linesearch->xnorm);
1507:       VecNormEnd(linesearch->vec_update,   NORM_2, &linesearch->ynorm);
1508:     }
1509:   }
1510:   return(0);
1511: }

1515: /*@
1516:    SNESLineSearchSetComputeNorms - Turns on or off the computation of final norms in the line search.

1518:    Input Parameters:
1519: +  linesearch  - linesearch context
1520: -  flg  - indicates whether or not to compute norms

1522:    Options Database Keys:
1523: .   -snes_linesearch_norms - turn norm computation on or off

1525:    Notes:
1526:    This is most relevant to the SNESLINESEARCHBASIC line search type.

1528:    Level: intermediate

1530: .seealso: SNESLineSearchGetNorms(), SNESLineSearchSetNorms(), SNESLineSearchComputeNorms(), SNESLINESEARCHBASIC
1531: @*/
1532: PetscErrorCode SNESLineSearchSetComputeNorms(SNESLineSearch linesearch, PetscBool flg)
1533: {
1535:   linesearch->norms = flg;
1536:   return(0);
1537: }

1541: /*@
1542:    SNESLineSearchGetVecs - Gets the vectors from the SNESLineSearch context

1544:    Input Parameters:
1545: .  linesearch - linesearch context

1547:    Output Parameters:
1548: +  X - Solution vector
1549: .  F - Function vector
1550: .  Y - Search direction vector
1551: .  W - Solution work vector
1552: -  G - Function work vector

1554:    Notes:
1555:    At the beginning of a line search application, X should contain a
1556:    solution and the vector F the function computed at X.  At the end of the
1557:    line search application, X should contain the new solution, and F the
1558:    function evaluated at the new solution.

1560:    These vectors are owned by the SNESLineSearch and should not be destroyed by the caller

1562:    Level: advanced

1564: .seealso: SNESLineSearchGetNorms(), SNESLineSearchSetVecs()
1565: @*/
1566: PetscErrorCode SNESLineSearchGetVecs(SNESLineSearch linesearch,Vec *X,Vec *F, Vec *Y,Vec *W,Vec *G)
1567: {
1570:   if (X) {
1572:     *X = linesearch->vec_sol;
1573:   }
1574:   if (F) {
1576:     *F = linesearch->vec_func;
1577:   }
1578:   if (Y) {
1580:     *Y = linesearch->vec_update;
1581:   }
1582:   if (W) {
1584:     *W = linesearch->vec_sol_new;
1585:   }
1586:   if (G) {
1588:     *G = linesearch->vec_func_new;
1589:   }
1590:   return(0);
1591: }

1595: /*@
1596:    SNESLineSearchSetVecs - Sets the vectors on the SNESLineSearch context

1598:    Input Parameters:
1599: +  linesearch - linesearch context
1600: .  X - Solution vector
1601: .  F - Function vector
1602: .  Y - Search direction vector
1603: .  W - Solution work vector
1604: -  G - Function work vector

1606:    Level: advanced

1608: .seealso: SNESLineSearchSetNorms(), SNESLineSearchGetVecs()
1609: @*/
1610: PetscErrorCode SNESLineSearchSetVecs(SNESLineSearch linesearch,Vec X,Vec F,Vec Y,Vec W, Vec G)
1611: {
1614:   if (X) {
1616:     linesearch->vec_sol = X;
1617:   }
1618:   if (F) {
1620:     linesearch->vec_func = F;
1621:   }
1622:   if (Y) {
1624:     linesearch->vec_update = Y;
1625:   }
1626:   if (W) {
1628:     linesearch->vec_sol_new = W;
1629:   }
1630:   if (G) {
1632:     linesearch->vec_func_new = G;
1633:   }
1634:   return(0);
1635: }

1639: /*@C
1640:    SNESLineSearchAppendOptionsPrefix - Appends to the prefix used for searching for all
1641:    SNES options in the database.

1643:    Logically Collective on SNESLineSearch

1645:    Input Parameters:
1646: +  snes - the SNES context
1647: -  prefix - the prefix to prepend to all option names

1649:    Notes:
1650:    A hyphen (-) must NOT be given at the beginning of the prefix name.
1651:    The first character of all runtime options is AUTOMATICALLY the hyphen.

1653:    Level: advanced

1655: .keywords: SNESLineSearch, append, options, prefix, database

1657: .seealso: SNESGetOptionsPrefix()
1658: @*/
1659: PetscErrorCode  SNESLineSearchAppendOptionsPrefix(SNESLineSearch linesearch,const char prefix[])
1660: {

1665:   PetscObjectAppendOptionsPrefix((PetscObject)linesearch,prefix);
1666:   return(0);
1667: }

1671: /*@C
1672:    SNESLineSearchGetOptionsPrefix - Sets the prefix used for searching for all
1673:    SNESLineSearch options in the database.

1675:    Not Collective

1677:    Input Parameter:
1678: .  linesearch - the SNESLineSearch context

1680:    Output Parameter:
1681: .  prefix - pointer to the prefix string used

1683:    Notes:
1684:    On the fortran side, the user should pass in a string 'prefix' of
1685:    sufficient length to hold the prefix.

1687:    Level: advanced

1689: .keywords: SNESLineSearch, get, options, prefix, database

1691: .seealso: SNESAppendOptionsPrefix()
1692: @*/
1693: PetscErrorCode  SNESLineSearchGetOptionsPrefix(SNESLineSearch linesearch,const char *prefix[])
1694: {

1699:   PetscObjectGetOptionsPrefix((PetscObject)linesearch,prefix);
1700:   return(0);
1701: }

1705: /*@C
1706:    SNESLineSearchSetWorkVecs - Gets work vectors for the line search.

1708:    Input Parameter:
1709: +  linesearch - the SNESLineSearch context
1710: -  nwork - the number of work vectors

1712:    Level: developer

1714:    Developers Note: This is PETSC_EXTERN because it may be used by user written plugin SNES implementations

1716: .keywords: SNESLineSearch, work, vector

1718: .seealso: SNESSetWorkVecs()
1719: @*/
1720: PetscErrorCode  SNESLineSearchSetWorkVecs(SNESLineSearch linesearch, PetscInt nwork)
1721: {

1725:   if (linesearch->vec_sol) {
1726:     VecDuplicateVecs(linesearch->vec_sol, nwork, &linesearch->work);
1727:   } else SETERRQ(PetscObjectComm((PetscObject)linesearch), PETSC_ERR_USER, "Cannot get linesearch work-vectors without setting a solution vec!");
1728:   return(0);
1729: }

1733: /*@
1734:    SNESLineSearchGetReason - Gets the success/failure status of the last line search application

1736:    Input Parameters:
1737: .  linesearch - linesearch context

1739:    Output Parameters:
1740: .  result - The success or failure status

1742:    Notes:
1743:    This is typically called after SNESLineSearchApply() in order to determine if the line-search failed
1744:    (and set the SNES convergence accordingly).

1746:    Level: intermediate

1748: .seealso: SNESLineSearchSetReason(), SNESLineSearchReason
1749: @*/
1750: PetscErrorCode  SNESLineSearchGetReason(SNESLineSearch linesearch, SNESLineSearchReason *result)
1751: {
1755:   *result = linesearch->result;
1756:   return(0);
1757: }

1761: /*@
1762:    SNESLineSearchSetReason - Sets the success/failure status of the last line search application

1764:    Input Parameters:
1765: +  linesearch - linesearch context
1766: -  result - The success or failure status

1768:    Notes:
1769:    This is typically called in a SNESLineSearchApply() or SNESLineSearchShell implementation to set
1770:    the success or failure of the line search method.

1772:    Level: developer

1774: .seealso: SNESLineSearchGetSResult()
1775: @*/
1776: PetscErrorCode  SNESLineSearchSetReason(SNESLineSearch linesearch, SNESLineSearchReason result)
1777: {
1780:   linesearch->result = result;
1781:   return(0);
1782: }

1786: /*@C
1787:    SNESLineSearchSetVIFunctions - Sets VI-specific functions for line search computation.

1789:    Input Parameters:
1790: +  snes - nonlinear context obtained from SNESCreate()
1791: .  projectfunc - function for projecting the function to the bounds
1792: -  normfunc - function for computing the norm of an active set

1794:    Logically Collective on SNES

1796:    Calling sequence of projectfunc:
1797: .vb
1798:    projectfunc (SNES snes, Vec X)
1799: .ve

1801:     Input parameters for projectfunc:
1802: +   snes - nonlinear context
1803: -   X - current solution

1805:     Output parameters for projectfunc:
1806: .   X - Projected solution

1808:    Calling sequence of normfunc:
1809: .vb
1810:    projectfunc (SNES snes, Vec X, Vec F, PetscScalar * fnorm)
1811: .ve

1813:     Input parameters for normfunc:
1814: +   snes - nonlinear context
1815: .   X - current solution
1816: -   F - current residual

1818:     Output parameters for normfunc:
1819: .   fnorm - VI-specific norm of the function

1821:     Notes:
1822:     The VI solvers require projection of the solution to the feasible set.  projectfunc should implement this.

1824:     The VI solvers require special evaluation of the function norm such that the norm is only calculated
1825:     on the inactive set.  This should be implemented by normfunc.

1827:     Level: developer

1829: .keywords: SNES, line search, VI, nonlinear, set, line search

1831: .seealso: SNESLineSearchGetVIFunctions(), SNESLineSearchSetPostCheck(), SNESLineSearchSetPreCheck()
1832: @*/
1833: extern PetscErrorCode SNESLineSearchSetVIFunctions(SNESLineSearch linesearch, SNESLineSearchVIProjectFunc projectfunc, SNESLineSearchVINormFunc normfunc)
1834: {
1837:   if (projectfunc) linesearch->ops->viproject = projectfunc;
1838:   if (normfunc) linesearch->ops->vinorm = normfunc;
1839:   return(0);
1840: }

1844: /*@C
1845:    SNESLineSearchGetVIFunctions - Sets VI-specific functions for line search computation.

1847:    Input Parameters:
1848: .  linesearch - the line search context, obtain with SNESGetLineSearch()

1850:    Output Parameters:
1851: +  projectfunc - function for projecting the function to the bounds
1852: -  normfunc - function for computing the norm of an active set

1854:    Logically Collective on SNES

1856:     Level: developer

1858: .keywords: SNES, line search, VI, nonlinear, get, line search

1860: .seealso: SNESLineSearchSetVIFunctions(), SNESLineSearchGetPostCheck(), SNESLineSearchGetPreCheck()
1861: @*/
1862: extern PetscErrorCode SNESLineSearchGetVIFunctions(SNESLineSearch linesearch, SNESLineSearchVIProjectFunc *projectfunc, SNESLineSearchVINormFunc *normfunc)
1863: {
1865:   if (projectfunc) *projectfunc = linesearch->ops->viproject;
1866:   if (normfunc) *normfunc = linesearch->ops->vinorm;
1867:   return(0);
1868: }

1872: /*@C
1873:   SNESLineSearchRegister - See SNESLineSearchRegister()

1875:   Level: advanced
1876: @*/
1877: PetscErrorCode  SNESLineSearchRegister(const char sname[],PetscErrorCode (*function)(SNESLineSearch))
1878: {

1882:   PetscFunctionListAdd(&SNESLineSearchList,sname,function);
1883:   return(0);
1884: }