Actual source code: linesearch.c

petsc-master 2017-01-16
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  1:  #include <petsc/private/linesearchimpl.h>

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

  6: PetscClassId  SNESLINESEARCH_CLASSID;
  7: PetscLogEvent SNESLINESEARCH_Apply;

  9: /*@
 10:    SNESLineSearchMonitorCancel - Clears all the monitor functions for a SNESLineSearch object.

 12:    Logically Collective on SNESLineSearch

 14:    Input Parameters:
 15: .  ls - the SNESLineSearch context

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

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

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

 28:    Level: intermediate

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

 32: .seealso: SNESLineSearchMonitorDefault(), SNESLineSearchMonitorSet()
 33: @*/
 34: PetscErrorCode  SNESLineSearchMonitorCancel(SNESLineSearch ls)
 35: {
 37:   PetscInt       i;

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

 50: /*@
 51:    SNESLineSearchMonitor - runs the user provided monitor routines, if they exist

 53:    Collective on SNES

 55:    Input Parameters:
 56: .  ls - the linesearch object

 58:    Notes:
 59:    This routine is called by the SNES implementations.
 60:    It does not typically need to be called by the user.

 62:    Level: developer

 64: .seealso: SNESLineSearchMonitorSet()
 65: @*/
 66: PetscErrorCode  SNESLineSearchMonitor(SNESLineSearch ls)
 67: {
 69:   PetscInt       i,n = ls->numbermonitors;

 72:   for (i=0; i<n; i++) {
 73:     (*ls->monitorftns[i])(ls,ls->monitorcontext[i]);
 74:   }
 75:   return(0);
 76: }

 78: /*@C
 79:    SNESLineSearchMonitorSet - Sets an ADDITIONAL function that is to be used at every
 80:    iteration of the nonlinear solver to display the iteration's
 81:    progress.

 83:    Logically Collective on SNESLineSearch

 85:    Input Parameters:
 86: +  ls - the SNESLineSearch context
 87: .  f - the monitor function
 88: .  mctx - [optional] user-defined context for private data for the
 89:           monitor routine (use NULL if no context is desired)
 90: -  monitordestroy - [optional] routine that frees monitor context
 91:           (may be NULL)

 93:    Notes:
 94:    Several different monitoring routines may be set by calling
 95:    SNESLineSearchMonitorSet() multiple times; all will be called in the
 96:    order in which they were set.

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

100:    Level: intermediate

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

104: .seealso: SNESLineSearchMonitorDefault(), SNESLineSearchMonitorCancel()
105: @*/
106: PetscErrorCode  SNESLineSearchMonitorSet(SNESLineSearch ls,PetscErrorCode (*f)(SNESLineSearch,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
107: {
109:   PetscInt       i;
110:   PetscBool      identical;
111: 
114:   for (i=0; i<ls->numbermonitors;i++) {
115:     PetscMonitorCompare((PetscErrorCode (*)(void))f,mctx,monitordestroy,(PetscErrorCode (*)(void))ls->monitorftns[i],ls->monitorcontext[i],ls->monitordestroy[i],&identical);
116:     if (identical) return(0);
117:   }
118:   if (ls->numbermonitors >= MAXSNESLSMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
119:   ls->monitorftns[ls->numbermonitors]          = f;
120:   ls->monitordestroy[ls->numbermonitors]   = monitordestroy;
121:   ls->monitorcontext[ls->numbermonitors++] = (void*)mctx;
122:   return(0);
123: }

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: }

159: /*@
160:    SNESLineSearchCreate - Creates the line search context.

162:    Logically Collective on Comm

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

167:    Output Parameters:
168: .  outlinesearch - the new linesearch context

170:    Level: developer

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

176: .keywords: LineSearch, create, context

178: .seealso: LineSearchDestroy(), SNESGetLineSearch()
179: @*/

181: PetscErrorCode SNESLineSearchCreate(MPI_Comm comm, SNESLineSearch *outlinesearch)
182: {
184:   SNESLineSearch linesearch;

188:   SNESInitializePackage();
189:   *outlinesearch = NULL;

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

193:   linesearch->vec_sol_new  = NULL;
194:   linesearch->vec_func_new = NULL;
195:   linesearch->vec_sol      = NULL;
196:   linesearch->vec_func     = NULL;
197:   linesearch->vec_update   = NULL;

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

220: /*@
221:    SNESLineSearchSetUp - Prepares the line search for being applied by allocating
222:    any required vectors.

224:    Collective on SNESLineSearch

226:    Input Parameters:
227: .  linesearch - The LineSearch instance.

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

236:    Level: advanced

238: .keywords: SNESLineSearch, SetUp

240: .seealso: SNESLineSearchReset()
241: @*/

243: PetscErrorCode SNESLineSearchSetUp(SNESLineSearch linesearch)
244: {

248:   if (!((PetscObject)linesearch)->type_name) {
249:     SNESLineSearchSetType(linesearch,SNESLINESEARCHBASIC);
250:   }
251:   if (!linesearch->setupcalled) {
252:     if (!linesearch->vec_sol_new) {
253:       VecDuplicate(linesearch->vec_sol, &linesearch->vec_sol_new);
254:     }
255:     if (!linesearch->vec_func_new) {
256:       VecDuplicate(linesearch->vec_sol, &linesearch->vec_func_new);
257:     }
258:     if (linesearch->ops->setup) {
259:       (*linesearch->ops->setup)(linesearch);
260:     }
261:     if (!linesearch->ops->snesfunc) {SNESLineSearchSetFunction(linesearch,SNESComputeFunction);}
262:     linesearch->lambda      = linesearch->damping;
263:     linesearch->setupcalled = PETSC_TRUE;
264:   }
265:   return(0);
266: }


269: /*@
270:    SNESLineSearchReset - Undoes the SNESLineSearchSetUp() and deletes any Vecs or Mats allocated by the line search.

272:    Collective on SNESLineSearch

274:    Input Parameters:
275: .  linesearch - The LineSearch instance.

277:    Notes: Usually only called by SNESReset()

279:    Level: developer

281: .keywords: SNESLineSearch, Reset

283: .seealso: SNESLineSearchSetUp()
284: @*/

286: PetscErrorCode SNESLineSearchReset(SNESLineSearch linesearch)
287: {

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

293:   VecDestroy(&linesearch->vec_sol_new);
294:   VecDestroy(&linesearch->vec_func_new);

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

298:   linesearch->nwork       = 0;
299:   linesearch->setupcalled = PETSC_FALSE;
300:   return(0);
301: }

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

306:    Input Parameters:
307: .  linesearch - the SNESLineSearch context
308: +  func       - function evaluation routine

310:    Level: developer

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

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

316: .seealso: SNESSetFunction()
317: @*/
318: PetscErrorCode  SNESLineSearchSetFunction(SNESLineSearch linesearch, PetscErrorCode (*func)(SNES,Vec,Vec))
319: {
322:   linesearch->ops->snesfunc = func;
323:   return(0);
324: }


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

330:      Synopsis:
331:      #include <petscsnes.h>
332:      SNESLineSearchPreCheckFunction(SNESLineSearch snes,Vec x,Vec y, PetscBool *changed);

334:        Input Parameters:
335: +      x - solution vector
336: .      y - search direction vector
337: -      changed - flag to indicate the precheck changed x or y.

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

342:    Level: advanced

344: .seealso:   SNESLineSearchSetPreCheck(), SNESLineSearchGetPreCheck(), SNESLineSearchSetPostCheck(), SNESLineSearchGetPostCheck() 
345: M*/

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

352:    Logically Collective on SNESLineSearch

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

359:    Level: intermediate

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

363: .seealso: SNESLineSearchSetPostCheck(), SNESLineSearchGetPostCheck(), SNESLineSearchGetPreCheck()
364: @*/
365: PetscErrorCode  SNESLineSearchSetPreCheck(SNESLineSearch linesearch, PetscErrorCode (*func)(SNESLineSearch,Vec,Vec,PetscBool*,void*),void *ctx)
366: {
369:   if (func) linesearch->ops->precheck = func;
370:   if (ctx) linesearch->precheckctx = ctx;
371:   return(0);
372: }

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

377:    Input Parameters:
378: .  linesearch - the SNESLineSearch context

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

384:    Level: intermediate

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

388: .seealso: SNESLineSearchGetPostCheck(), SNESLineSearchSetPreCheck()
389: @*/
390: PetscErrorCode  SNESLineSearchGetPreCheck(SNESLineSearch linesearch, PetscErrorCode (**func)(SNESLineSearch,Vec,Vec,PetscBool*,void*),void **ctx)
391: {
394:   if (func) *func = linesearch->ops->precheck;
395:   if (ctx) *ctx = linesearch->precheckctx;
396:   return(0);
397: }

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

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

406:      Input Parameters:
407: +      x - old solution vector
408: .      y - search direction vector
409: .      w - new solution vector
410: .      changed_y - indicates that the line search changed y
411: -      changed_w - indicates that the line search changed w

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

416:    Level: advanced

418: .seealso:   SNESLineSearchSetPreCheck(), SNESLineSearchSetPostCheck(), SNESLineSearchGetPreCheck(), SNESLineSearchGetPostCheck()
419: M*/

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

425:    Logically Collective on SNESLineSearch

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

432:    Level: intermediate

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

436: .seealso: SNESLineSearchSetPreCheck()
437: @*/
438: PetscErrorCode  SNESLineSearchSetPostCheck(SNESLineSearch linesearch, PetscErrorCode (*func)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*),void *ctx)
439: {
442:   if (func) linesearch->ops->postcheck = func;
443:   if (ctx) linesearch->postcheckctx = ctx;
444:   return(0);
445: }

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

450:    Input Parameters:
451: .  linesearch - the SNESLineSearch context

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

457:    Level: intermediate

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

461: .seealso: SNESLineSearchGetPreCheck(), SNESLineSearchSetPostCheck()
462: @*/
463: PetscErrorCode  SNESLineSearchGetPostCheck(SNESLineSearch linesearch, PetscErrorCode (**func)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*),void **ctx)
464: {
467:   if (func) *func = linesearch->ops->postcheck;
468:   if (ctx) *ctx = linesearch->postcheckctx;
469:   return(0);
470: }

472: /*@
473:    SNESLineSearchPreCheck - Prepares the line search for being applied.

475:    Logically Collective on SNESLineSearch

477:    Input Parameters:
478: +  linesearch - The linesearch instance.
479: .  X - The current solution
480: -  Y - The step direction

482:    Output Parameters:
483: .  changed - Indicator that the precheck routine has changed anything

485:    Level: developer

487: .keywords: SNESLineSearch, Create

489: .seealso: SNESLineSearchPostCheck()
490: @*/
491: PetscErrorCode SNESLineSearchPreCheck(SNESLineSearch linesearch,Vec X,Vec Y,PetscBool *changed)
492: {

496:   *changed = PETSC_FALSE;
497:   if (linesearch->ops->precheck) {
498:     (*linesearch->ops->precheck)(linesearch, X, Y, changed, linesearch->precheckctx);
500:   }
501:   return(0);
502: }

504: /*@
505:    SNESLineSearchPostCheck - Prepares the line search for being applied.

507:    Logically Collective on SNESLineSearch

509:    Input Parameters:
510: +  linesearch - The linesearch context
511: .  X - The last solution
512: .  Y - The step direction
513: -  W - The updated solution, W = X + lambda*Y for some lambda

515:    Output Parameters:
516: +  changed_Y - Indicator if the direction Y has been changed.
517: -  changed_W - Indicator if the new candidate solution W has been changed.

519:    Level: developer

521: .keywords: SNESLineSearch, Create

523: .seealso: SNESLineSearchPreCheck()
524: @*/
525: PetscErrorCode SNESLineSearchPostCheck(SNESLineSearch linesearch,Vec X,Vec Y,Vec W,PetscBool *changed_Y,PetscBool *changed_W)
526: {

530:   *changed_Y = PETSC_FALSE;
531:   *changed_W = PETSC_FALSE;
532:   if (linesearch->ops->postcheck) {
533:     (*linesearch->ops->postcheck)(linesearch,X,Y,W,changed_Y,changed_W,linesearch->postcheckctx);
536:   }
537:   return(0);
538: }

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

543:    Logically Collective on SNESLineSearch

545:    Input Arguments:
546: +  linesearch - linesearch context
547: .  X - base state for this step
548: .  Y - initial correction
549: -  ctx - context for this function

551:    Output Arguments:
552: +  Y - correction, possibly modified
553: -  changed - flag indicating that Y was modified

555:    Options Database Key:
556: +  -snes_linesearch_precheck_picard - activate this routine
557: -  -snes_linesearch_precheck_picard_angle - angle

559:    Level: advanced

561:    Notes:
562:    This function should be passed to SNESLineSearchSetPreCheck()

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

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

571: .seealso: SNESLineSearchSetPreCheck()
572: @*/
573: PetscErrorCode SNESLineSearchPreCheckPicard(SNESLineSearch linesearch,Vec X,Vec Y,PetscBool *changed,void *ctx)
574: {
576:   PetscReal      angle = *(PetscReal*)linesearch->precheckctx;
577:   Vec            Ylast;
578:   PetscScalar    dot;
579:   PetscInt       iter;
580:   PetscReal      ynorm,ylastnorm,theta,angle_radians;
581:   SNES           snes;

584:   SNESLineSearchGetSNES(linesearch, &snes);
585:   PetscObjectQuery((PetscObject)snes,"SNESLineSearchPreCheckPicard_Ylast",(PetscObject*)&Ylast);
586:   if (!Ylast) {
587:     VecDuplicate(Y,&Ylast);
588:     PetscObjectCompose((PetscObject)snes,"SNESLineSearchPreCheckPicard_Ylast",(PetscObject)Ylast);
589:     PetscObjectDereference((PetscObject)Ylast);
590:   }
591:   SNESGetIterationNumber(snes,&iter);
592:   if (iter < 2) {
593:     VecCopy(Y,Ylast);
594:     *changed = PETSC_FALSE;
595:     return(0);
596:   }

598:   VecDot(Y,Ylast,&dot);
599:   VecNorm(Y,NORM_2,&ynorm);
600:   VecNorm(Ylast,NORM_2,&ylastnorm);
601:   /* Compute the angle between the vectors Y and Ylast, clip to keep inside the domain of acos() */
602:   theta         = PetscAcosReal((PetscReal)PetscClipInterval(PetscAbsScalar(dot) / (ynorm * ylastnorm),-1.0,1.0));
603:   angle_radians = angle * PETSC_PI / 180.;
604:   if (PetscAbsReal(theta) < angle_radians || PetscAbsReal(theta - PETSC_PI) < angle_radians) {
605:     /* Modify the step Y */
606:     PetscReal alpha,ydiffnorm;
607:     VecAXPY(Ylast,-1.0,Y);
608:     VecNorm(Ylast,NORM_2,&ydiffnorm);
609:     alpha = ylastnorm / ydiffnorm;
610:     VecCopy(Y,Ylast);
611:     VecScale(Y,alpha);
612:     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);
613:   } else {
614:     PetscInfo2(snes,"Angle %14.12e degrees exceeds threshold %14.12e, no correction applied\n",(double)(theta*180./PETSC_PI),(double)angle);
615:     VecCopy(Y,Ylast);
616:     *changed = PETSC_FALSE;
617:   }
618:   return(0);
619: }

621: /*@
622:    SNESLineSearchApply - Computes the line-search update.

624:    Collective on SNESLineSearch

626:    Input Parameters:
627: +  linesearch - The linesearch context
628: .  X - The current solution
629: .  F - The current function
630: .  fnorm - The current norm
631: -  Y - The search direction

633:    Output Parameters:
634: +  X - The new solution
635: .  F - The new function
636: -  fnorm - The new function norm

638:    Options Database Keys:
639: + -snes_linesearch_type - basic, bt, l2, cp, nleqerr, shell
640: . -snes_linesearch_monitor [:filename] - Print progress of line searches
641: . -snes_linesearch_damping - The linesearch damping parameter
642: . -snes_linesearch_norms   - Turn on/off the linesearch norms
643: . -snes_linesearch_keeplambda - Keep the previous search length as the initial guess
644: - -snes_linesearch_max_it - The number of iterations for iterative line searches

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

654:    Level: Intermediate

656: .keywords: SNESLineSearch, Create

658: .seealso: SNESLineSearchCreate(), SNESLineSearchPreCheck(), SNESLineSearchPostCheck(), SNESSolve(), SNESComputeFunction()
659: @*/
660: PetscErrorCode SNESLineSearchApply(SNESLineSearch linesearch, Vec X, Vec F, PetscReal * fnorm, Vec Y)
661: {


670:   linesearch->result = SNES_LINESEARCH_SUCCEEDED;

672:   linesearch->vec_sol    = X;
673:   linesearch->vec_update = Y;
674:   linesearch->vec_func   = F;

676:   SNESLineSearchSetUp(linesearch);

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

680:   if (fnorm) linesearch->fnorm = *fnorm;
681:   else {
682:     VecNorm(F, NORM_2, &linesearch->fnorm);
683:   }

685:   PetscLogEventBegin(SNESLINESEARCH_Apply,linesearch,X,F,Y);

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

689:   PetscLogEventEnd(SNESLINESEARCH_Apply,linesearch,X,F,Y);

691:   if (fnorm) *fnorm = linesearch->fnorm;
692:   return(0);
693: }

695: /*@
696:    SNESLineSearchDestroy - Destroys the line search instance.

698:    Collective on SNESLineSearch

700:    Input Parameters:
701: .  linesearch - The linesearch context

703:    Level: Intermediate

705: .keywords: SNESLineSearch, Destroy

707: .seealso: SNESLineSearchCreate(), SNESLineSearchReset(), SNESDestroy()
708: @*/
709: PetscErrorCode SNESLineSearchDestroy(SNESLineSearch * linesearch)
710: {

714:   if (!*linesearch) return(0);
716:   if (--((PetscObject)(*linesearch))->refct > 0) {*linesearch = 0; return(0);}
717:   PetscObjectSAWsViewOff((PetscObject)*linesearch);
718:   SNESLineSearchReset(*linesearch);
719:   if ((*linesearch)->ops->destroy) (*linesearch)->ops->destroy(*linesearch);
720:   PetscViewerDestroy(&(*linesearch)->monitor);
721:   SNESLineSearchMonitorCancel((*linesearch));
722:   PetscHeaderDestroy(linesearch);
723:   return(0);
724: }

726: /*@
727:    SNESLineSearchSetDefaultMonitor - Turns on/off printing useful information and debugging output about the line search.

729:    Input Parameters:
730: +  linesearch - the linesearch object
731: -  viewer - an ASCII PetscViewer or NULL to turn off monitor

733:    Logically Collective on SNESLineSearch

735:    Options Database:
736: .   -snes_linesearch_monitor [:filename] - enables the monitor

738:    Level: intermediate

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

744: .seealso: SNESLineSearchGetDefaultMonitor(), PetscViewer, SNESLineSearchSetMonitor()
745: @*/
746: PetscErrorCode  SNESLineSearchSetDefaultMonitor(SNESLineSearch linesearch, PetscViewer viewer)
747: {

751:   if (viewer) {PetscObjectReference((PetscObject)viewer);}
752:   PetscViewerDestroy(&linesearch->monitor);
753:   linesearch->monitor = viewer;
754:   return(0);
755: }

757: /*@
758:    SNESLineSearchGetDefaultMonitor - Gets the PetscViewer instance for the line search monitor.

760:    Input Parameter:
761: .  linesearch - linesearch context

763:    Output Parameter:
764: .  monitor - monitor context

766:    Logically Collective on SNES

768:    Options Database Keys:
769: .   -snes_linesearch_monitor - enables the monitor

771:    Level: intermediate

773: .seealso: SNESLineSearchSetDefaultMonitor(), PetscViewer
774: @*/
775: PetscErrorCode  SNESLineSearchGetDefaultMonitor(SNESLineSearch linesearch, PetscViewer *monitor)
776: {
779:   if (monitor) {
781:     *monitor = linesearch->monitor;
782:   }
783:   return(0);
784: }

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

789:    Collective on SNESLineSearch

791:    Input Parameters:
792: +  ls - LineSearch object you wish to monitor
793: .  name - the monitor type one is seeking
794: .  help - message indicating what monitoring is done
795: .  manual - manual page for the monitor
796: .  monitor - the monitor function
797: -  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

799:    Level: developer

801: .seealso: PetscOptionsGetViewer(), PetscOptionsGetReal(), PetscOptionsHasName(), PetscOptionsGetString(),
802:           PetscOptionsGetIntArray(), PetscOptionsGetRealArray(), PetscOptionsBool()
803:           PetscOptionsInt(), PetscOptionsString(), PetscOptionsReal(), PetscOptionsBool(),
804:           PetscOptionsName(), PetscOptionsBegin(), PetscOptionsEnd(), PetscOptionsHead(),
805:           PetscOptionsStringArray(),PetscOptionsRealArray(), PetscOptionsScalar(),
806:           PetscOptionsBoolGroupBegin(), PetscOptionsBoolGroup(), PetscOptionsBoolGroupEnd(),
807:           PetscOptionsFList(), PetscOptionsEList()
808: @*/
809: PetscErrorCode  SNESLineSearchMonitorSetFromOptions(SNESLineSearch ls,const char name[],const char help[], const char manual[],PetscErrorCode (*monitor)(SNESLineSearch,PetscViewerAndFormat*),PetscErrorCode (*monitorsetup)(SNESLineSearch,PetscViewerAndFormat*))
810: {
811:   PetscErrorCode    ierr;
812:   PetscViewer       viewer;
813:   PetscViewerFormat format;
814:   PetscBool         flg;

817:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)ls),((PetscObject)ls)->prefix,name,&viewer,&format,&flg);
818:   if (flg) {
819:     PetscViewerAndFormat *vf;
820:     PetscViewerAndFormatCreate(viewer,format,&vf);
821:     PetscObjectDereference((PetscObject)viewer);
822:     if (monitorsetup) {
823:       (*monitorsetup)(ls,vf);
824:     }
825:     SNESLineSearchMonitorSet(ls,(PetscErrorCode (*)(SNESLineSearch,void*))monitor,vf,(PetscErrorCode (*)(void**))PetscViewerAndFormatDestroy);
826:   }
827:   return(0);
828: }

830: /*@
831:    SNESLineSearchSetFromOptions - Sets options for the line search

833:    Input Parameters:
834: .  linesearch - linesearch context

836:    Options Database Keys:
837: + -snes_linesearch_type <type> - basic, bt, l2, cp, nleqerr, shell
838: . -snes_linesearch_order <order> - 1, 2, 3.  Most types only support certain orders (bt supports 2 or 3)
839: . -snes_linesearch_norms   - Turn on/off the linesearch norms for the basic linesearch type
840: . -snes_linesearch_minlambda - The minimum step length
841: . -snes_linesearch_maxstep - The maximum step size
842: . -snes_linesearch_rtol - Relative tolerance for iterative line searches
843: . -snes_linesearch_atol - Absolute tolerance for iterative line searches
844: . -snes_linesearch_ltol - Change in lambda tolerance for iterative line searches
845: . -snes_linesearch_max_it - The number of iterations for iterative line searches
846: . -snes_linesearch_monitor [:filename] - Print progress of line searches
847: . -snes_linesearch_monitor_solution_update [viewer:filename:format] - view each update tried by line search routine
848: . -snes_linesearch_damping - The linesearch damping parameter
849: . -snes_linesearch_keeplambda - Keep the previous search length as the initial guess.
850: . -snes_linesearch_precheck_picard - Use precheck that speeds up convergence of picard method
851: - -snes_linesearch_precheck_picard_angle - Angle used in picard precheck method

853:    Logically Collective on SNESLineSearch

855:    Level: intermediate

857: .seealso: SNESLineSearchCreate(), SNESLineSearchSetOrder(), SNESLineSearchSetType(), SNESLineSearchSetTolerances(), SNESLineSearchSetDamping(), SNESLineSearchPreCheckPicard()
858: @*/
859: PetscErrorCode SNESLineSearchSetFromOptions(SNESLineSearch linesearch)
860: {
861:   PetscErrorCode    ierr;
862:   const char        *deft = SNESLINESEARCHBASIC;
863:   char              type[256];
864:   PetscBool         flg, set;
865:   PetscViewer       viewer;

868:   SNESLineSearchRegisterAll();

870:   PetscObjectOptionsBegin((PetscObject)linesearch);
871:   if (((PetscObject)linesearch)->type_name) deft = ((PetscObject)linesearch)->type_name;
872:   PetscOptionsFList("-snes_linesearch_type","Linesearch type","SNESLineSearchSetType",SNESLineSearchList,deft,type,256,&flg);
873:   if (flg) {
874:     SNESLineSearchSetType(linesearch,type);
875:   } else if (!((PetscObject)linesearch)->type_name) {
876:     SNESLineSearchSetType(linesearch,deft);
877:   }

879:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)linesearch),((PetscObject)linesearch)->prefix,"-snes_linesearch_monitor",&viewer,NULL,&set);
880:   if (set) {
881:     SNESLineSearchSetDefaultMonitor(linesearch,viewer);
882:     PetscViewerDestroy(&viewer);
883:   }
884:   SNESLineSearchMonitorSetFromOptions(linesearch,"-snes_linesearch_monitor_solution_update","View correction at each iteration","SNESLineSearchMonitorSolutionUpdate",SNESLineSearchMonitorSolutionUpdate,NULL);
885: 
886:   /* tolerances */
887:   PetscOptionsReal("-snes_linesearch_minlambda","Minimum step length","SNESLineSearchSetTolerances",linesearch->steptol,&linesearch->steptol,NULL);
888:   PetscOptionsReal("-snes_linesearch_maxstep","Maximum step size","SNESLineSearchSetTolerances",linesearch->maxstep,&linesearch->maxstep,NULL);
889:   PetscOptionsReal("-snes_linesearch_rtol","Relative tolerance for iterative line search","SNESLineSearchSetTolerances",linesearch->rtol,&linesearch->rtol,NULL);
890:   PetscOptionsReal("-snes_linesearch_atol","Absolute tolerance for iterative line search","SNESLineSearchSetTolerances",linesearch->atol,&linesearch->atol,NULL);
891:   PetscOptionsReal("-snes_linesearch_ltol","Change in lambda tolerance for iterative line search","SNESLineSearchSetTolerances",linesearch->ltol,&linesearch->ltol,NULL);
892:   PetscOptionsInt("-snes_linesearch_max_it","Maximum iterations for iterative line searches","SNESLineSearchSetTolerances",linesearch->max_its,&linesearch->max_its,NULL);

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

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

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

905:       PetscOptionsReal("-snes_linesearch_precheck_picard_angle","Maximum angle at which to activate the correction",
906:                               "none",linesearch->precheck_picard_angle,&linesearch->precheck_picard_angle,NULL);
907:       SNESLineSearchSetPreCheck(linesearch,SNESLineSearchPreCheckPicard,&linesearch->precheck_picard_angle);
908:     } else {
909:       SNESLineSearchSetPreCheck(linesearch,NULL,NULL);
910:     }
911:   }
912:   PetscOptionsInt("-snes_linesearch_order","Order of approximation used in the line search","SNESLineSearchSetOrder",linesearch->order,&linesearch->order,NULL);
913:   PetscOptionsBool("-snes_linesearch_norms","Compute final norms in line search","SNESLineSearchSetComputeNorms",linesearch->norms,&linesearch->norms,NULL);

915:   if (linesearch->ops->setfromoptions) {
916:     (*linesearch->ops->setfromoptions)(PetscOptionsObject,linesearch);
917:   }

919:   PetscObjectProcessOptionsHandlers(PetscOptionsObject,(PetscObject)linesearch);
920:   PetscOptionsEnd();
921:   return(0);
922: }

924: /*@
925:    SNESLineSearchView - Prints useful information about the line search

927:    Input Parameters:
928: .  linesearch - linesearch context

930:    Logically Collective on SNESLineSearch

932:    Level: intermediate

934: .seealso: SNESLineSearchCreate()
935: @*/
936: PetscErrorCode SNESLineSearchView(SNESLineSearch linesearch, PetscViewer viewer)
937: {
939:   PetscBool      iascii;

943:   if (!viewer) {
944:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)linesearch),&viewer);
945:   }

949:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
950:   if (iascii) {
951:     PetscObjectPrintClassNamePrefixType((PetscObject)linesearch,viewer);
952:     if (linesearch->ops->view) {
953:       PetscViewerASCIIPushTab(viewer);
954:       (*linesearch->ops->view)(linesearch,viewer);
955:       PetscViewerASCIIPopTab(viewer);
956:     }
957:     PetscViewerASCIIPrintf(viewer,"  maxstep=%e, minlambda=%e\n", (double)linesearch->maxstep,(double)linesearch->steptol);
958:     PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%e, absolute=%e, lambda=%e\n", (double)linesearch->rtol,(double)linesearch->atol,(double)linesearch->ltol);
959:     PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D\n", linesearch->max_its);
960:     if (linesearch->ops->precheck) {
961:       if (linesearch->ops->precheck == SNESLineSearchPreCheckPicard) {
962:         PetscViewerASCIIPrintf(viewer,"  using precheck step to speed up Picard convergence\n", linesearch->max_its);
963:       } else {
964:         PetscViewerASCIIPrintf(viewer,"  using user-defined precheck step\n", linesearch->max_its);
965:       }
966:     }
967:     if (linesearch->ops->postcheck) {
968:       PetscViewerASCIIPrintf(viewer,"  using user-defined postcheck step\n", linesearch->max_its);
969:     }
970:   }
971:   return(0);
972: }

974: /*@C
975:    SNESLineSearchSetType - Sets the linesearch type

977:    Logically Collective on SNESLineSearch

979:    Input Parameters:
980: +  linesearch - linesearch context
981: -  type - The type of line search to be used

983:    Available Types:
984: +  basic - Simple damping line search.
985: .  bt - Backtracking line search over the L2 norm of the function
986: .  l2 - Secant line search over the L2 norm of the function
987: .  cp - Critical point secant line search assuming F(x) = grad G(x) for some unknown G(x)
988: .  nleqerr - Affine-covariant error-oriented linesearch
989: -  shell - User provided SNESLineSearch implementation

991:    Level: intermediate

993: .seealso: SNESLineSearchCreate()
994: @*/
995: PetscErrorCode SNESLineSearchSetType(SNESLineSearch linesearch, SNESLineSearchType type)
996: {
997:   PetscErrorCode ierr,(*r)(SNESLineSearch);
998:   PetscBool      match;


1004:   PetscObjectTypeCompare((PetscObject)linesearch,type,&match);
1005:   if (match) return(0);

1007:   PetscFunctionListFind(SNESLineSearchList,type,&r);
1008:   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested Line Search type %s",type);
1009:   /* Destroy the previous private linesearch context */
1010:   if (linesearch->ops->destroy) {
1011:     (*(linesearch)->ops->destroy)(linesearch);

1013:     linesearch->ops->destroy = NULL;
1014:   }
1015:   /* Reinitialize function pointers in SNESLineSearchOps structure */
1016:   linesearch->ops->apply          = 0;
1017:   linesearch->ops->view           = 0;
1018:   linesearch->ops->setfromoptions = 0;
1019:   linesearch->ops->destroy        = 0;

1021:   PetscObjectChangeTypeName((PetscObject)linesearch,type);
1022:   (*r)(linesearch);
1023:   return(0);
1024: }

1026: /*@
1027:    SNESLineSearchSetSNES - Sets the SNES for the linesearch for function evaluation.

1029:    Input Parameters:
1030: +  linesearch - linesearch context
1031: -  snes - The snes instance

1033:    Level: developer

1035:    Notes:
1036:    This happens automatically when the line search is obtained/created with
1037:    SNESGetLineSearch().  This routine is therefore mainly called within SNES
1038:    implementations.

1040:    Level: developer

1042: .seealso: SNESLineSearchGetSNES(), SNESLineSearchSetVecs(), SNES
1043: @*/
1044: PetscErrorCode  SNESLineSearchSetSNES(SNESLineSearch linesearch, SNES snes)
1045: {
1049:   linesearch->snes = snes;
1050:   return(0);
1051: }

1053: /*@
1054:    SNESLineSearchGetSNES - Gets the SNES instance associated with the line search.
1055:    Having an associated SNES is necessary because most line search implementations must be able to
1056:    evaluate the function using SNESComputeFunction() for the associated SNES.  This routine
1057:    is used in the line search implementations when one must get this associated SNES instance.

1059:    Input Parameters:
1060: .  linesearch - linesearch context

1062:    Output Parameters:
1063: .  snes - The snes instance

1065:    Level: developer

1067: .seealso: SNESLineSearchGetSNES(), SNESLineSearchSetVecs(), SNES
1068: @*/
1069: PetscErrorCode  SNESLineSearchGetSNES(SNESLineSearch linesearch, SNES *snes)
1070: {
1074:   *snes = linesearch->snes;
1075:   return(0);
1076: }

1078: /*@
1079:    SNESLineSearchGetLambda - Gets the last linesearch steplength discovered.

1081:    Input Parameters:
1082: .  linesearch - linesearch context

1084:    Output Parameters:
1085: .  lambda - The last steplength computed during SNESLineSearchApply()

1087:    Level: advanced

1089:    Notes:
1090:    This is useful in methods where the solver is ill-scaled and
1091:    requires some adaptive notion of the difference in scale between the
1092:    solution and the function.  For instance, SNESQN may be scaled by the
1093:    line search lambda using the argument -snes_qn_scaling ls.

1095: .seealso: SNESLineSearchSetLambda(), SNESLineSearchGetDamping(), SNESLineSearchApply()
1096: @*/
1097: PetscErrorCode  SNESLineSearchGetLambda(SNESLineSearch linesearch,PetscReal *lambda)
1098: {
1102:   *lambda = linesearch->lambda;
1103:   return(0);
1104: }

1106: /*@
1107:    SNESLineSearchSetLambda - Sets the linesearch steplength.

1109:    Input Parameters:
1110: +  linesearch - linesearch context
1111: -  lambda - The last steplength.

1113:    Notes:
1114:    This routine is typically used within implementations of SNESLineSearchApply()
1115:    to set the final steplength.  This routine (and SNESLineSearchGetLambda()) were
1116:    added in order to facilitate Quasi-Newton methods that use the previous steplength
1117:    as an inner scaling parameter.

1119:    Level: advanced

1121: .seealso: SNESLineSearchGetLambda()
1122: @*/
1123: PetscErrorCode  SNESLineSearchSetLambda(SNESLineSearch linesearch, PetscReal lambda)
1124: {
1127:   linesearch->lambda = lambda;
1128:   return(0);
1129: }

1131: /*@
1132:    SNESLineSearchGetTolerances - Gets the tolerances for the linesearch.  These include
1133:    tolerances for the relative and absolute change in the function norm, the change
1134:    in lambda for iterative line searches, the minimum steplength, the maximum steplength,
1135:    and the maximum number of iterations the line search procedure may take.

1137:    Input Parameters:
1138: .  linesearch - linesearch context

1140:    Output Parameters:
1141: +  steptol - The minimum steplength
1142: .  maxstep - The maximum steplength
1143: .  rtol    - The relative tolerance for iterative line searches
1144: .  atol    - The absolute tolerance for iterative line searches
1145: .  ltol    - The change in lambda tolerance for iterative line searches
1146: -  max_it  - The maximum number of iterations of the line search

1148:    Level: intermediate

1150:    Notes:
1151:    Different line searches may implement these parameters slightly differently as
1152:    the type requires.

1154: .seealso: SNESLineSearchSetTolerances()
1155: @*/
1156: PetscErrorCode  SNESLineSearchGetTolerances(SNESLineSearch linesearch,PetscReal *steptol,PetscReal *maxstep, PetscReal *rtol, PetscReal *atol, PetscReal *ltol, PetscInt *max_its)
1157: {
1160:   if (steptol) {
1162:     *steptol = linesearch->steptol;
1163:   }
1164:   if (maxstep) {
1166:     *maxstep = linesearch->maxstep;
1167:   }
1168:   if (rtol) {
1170:     *rtol = linesearch->rtol;
1171:   }
1172:   if (atol) {
1174:     *atol = linesearch->atol;
1175:   }
1176:   if (ltol) {
1178:     *ltol = linesearch->ltol;
1179:   }
1180:   if (max_its) {
1182:     *max_its = linesearch->max_its;
1183:   }
1184:   return(0);
1185: }

1187: /*@
1188:    SNESLineSearchSetTolerances -  Gets the tolerances for the linesearch.  These include
1189:    tolerances for the relative and absolute change in the function norm, the change
1190:    in lambda for iterative line searches, the minimum steplength, the maximum steplength,
1191:    and the maximum number of iterations the line search procedure may take.

1193:    Input Parameters:
1194: +  linesearch - linesearch context
1195: .  steptol - The minimum steplength
1196: .  maxstep - The maximum steplength
1197: .  rtol    - The relative tolerance for iterative line searches
1198: .  atol    - The absolute tolerance for iterative line searches
1199: .  ltol    - The change in lambda tolerance for iterative line searches
1200: -  max_it  - The maximum number of iterations of the line search

1202:    Notes:
1203:    The user may choose to not set any of the tolerances using PETSC_DEFAULT in
1204:    place of an argument.

1206:    Level: intermediate

1208: .seealso: SNESLineSearchGetTolerances()
1209: @*/
1210: PetscErrorCode  SNESLineSearchSetTolerances(SNESLineSearch linesearch,PetscReal steptol,PetscReal maxstep, PetscReal rtol, PetscReal atol, PetscReal ltol, PetscInt max_its)
1211: {

1221:   if (steptol!= PETSC_DEFAULT) {
1222:     if (steptol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Minimum step length %14.12e must be non-negative",(double)steptol);
1223:     linesearch->steptol = steptol;
1224:   }

1226:   if (maxstep!= PETSC_DEFAULT) {
1227:     if (maxstep < 0.0) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Maximum step length %14.12e must be non-negative",(double)maxstep);
1228:     linesearch->maxstep = maxstep;
1229:   }

1231:   if (rtol != PETSC_DEFAULT) {
1232:     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);
1233:     linesearch->rtol = rtol;
1234:   }

1236:   if (atol != PETSC_DEFAULT) {
1237:     if (atol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %14.12e must be non-negative",(double)atol);
1238:     linesearch->atol = atol;
1239:   }

1241:   if (ltol != PETSC_DEFAULT) {
1242:     if (ltol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Labmda tolerance %14.12e must be non-negative",(double)ltol);
1243:     linesearch->ltol = ltol;
1244:   }

1246:   if (max_its != PETSC_DEFAULT) {
1247:     if (max_its < 0) SETERRQ1(PetscObjectComm((PetscObject)linesearch),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",max_its);
1248:     linesearch->max_its = max_its;
1249:   }
1250:   return(0);
1251: }

1253: /*@
1254:    SNESLineSearchGetDamping - Gets the line search damping parameter.

1256:    Input Parameters:
1257: .  linesearch - linesearch context

1259:    Output Parameters:
1260: .  damping - The damping parameter

1262:    Level: advanced

1264: .seealso: SNESLineSearchGetStepTolerance(), SNESQN
1265: @*/

1267: PetscErrorCode  SNESLineSearchGetDamping(SNESLineSearch linesearch,PetscReal *damping)
1268: {
1272:   *damping = linesearch->damping;
1273:   return(0);
1274: }

1276: /*@
1277:    SNESLineSearchSetDamping - Sets the line search damping paramter.

1279:    Input Parameters:
1280: +  linesearch - linesearch context
1281: -  damping - The damping parameter

1283:    Options Database:
1284: .   -snes_linesearch_damping
1285:    Level: intermediate

1287:    Notes:
1288:    The basic line search merely takes the update step scaled by the damping parameter.
1289:    The use of the damping parameter in the l2 and cp line searches is much more subtle;
1290:    it is used as a starting point in calculating the secant step. However, the eventual
1291:    step may be of greater length than the damping parameter.  In the bt line search it is
1292:    used as the maximum possible step length, as the bt line search only backtracks.

1294: .seealso: SNESLineSearchGetDamping()
1295: @*/
1296: PetscErrorCode  SNESLineSearchSetDamping(SNESLineSearch linesearch,PetscReal damping)
1297: {
1300:   linesearch->damping = damping;
1301:   return(0);
1302: }

1304: /*@
1305:    SNESLineSearchGetOrder - Gets the line search approximation order.

1307:    Input Parameters:
1308: .  linesearch - linesearch context

1310:    Output Parameters:
1311: .  order - The order

1313:    Possible Values for order:
1314: +  1 or SNES_LINESEARCH_ORDER_LINEAR - linear order
1315: .  2 or SNES_LINESEARCH_ORDER_QUADRATIC - quadratic order
1316: -  3 or SNES_LINESEARCH_ORDER_CUBIC - cubic order

1318:    Level: intermediate

1320: .seealso: SNESLineSearchSetOrder()
1321: @*/

1323: PetscErrorCode  SNESLineSearchGetOrder(SNESLineSearch linesearch,PetscInt *order)
1324: {
1328:   *order = linesearch->order;
1329:   return(0);
1330: }

1332: /*@
1333:    SNESLineSearchSetOrder - Sets the line search damping paramter.

1335:    Input Parameters:
1336: .  linesearch - linesearch context
1337: .  order - The damping parameter

1339:    Level: intermediate

1341:    Possible Values for order:
1342: +  1 or SNES_LINESEARCH_ORDER_LINEAR - linear order
1343: .  2 or SNES_LINESEARCH_ORDER_QUADRATIC - quadratic order
1344: -  3 or SNES_LINESEARCH_ORDER_CUBIC - cubic order

1346:    Notes:
1347:    Variable orders are supported by the following line searches:
1348: +  bt - cubic and quadratic
1349: -  cp - linear and quadratic

1351: .seealso: SNESLineSearchGetOrder()
1352: @*/
1353: PetscErrorCode  SNESLineSearchSetOrder(SNESLineSearch linesearch,PetscInt order)
1354: {
1357:   linesearch->order = order;
1358:   return(0);
1359: }

1361: /*@
1362:    SNESLineSearchGetNorms - Gets the norms for for X, Y, and F.

1364:    Input Parameters:
1365: .  linesearch - linesearch context

1367:    Output Parameters:
1368: +  xnorm - The norm of the current solution
1369: .  fnorm - The norm of the current function
1370: -  ynorm - The norm of the current update

1372:    Notes:
1373:    This function is mainly called from SNES implementations.

1375:    Level: developer

1377: .seealso: SNESLineSearchSetNorms() SNESLineSearchGetVecs()
1378: @*/
1379: PetscErrorCode  SNESLineSearchGetNorms(SNESLineSearch linesearch, PetscReal * xnorm, PetscReal * fnorm, PetscReal * ynorm)
1380: {
1383:   if (xnorm) *xnorm = linesearch->xnorm;
1384:   if (fnorm) *fnorm = linesearch->fnorm;
1385:   if (ynorm) *ynorm = linesearch->ynorm;
1386:   return(0);
1387: }

1389: /*@
1390:    SNESLineSearchSetNorms - Gets the computed norms for for X, Y, and F.

1392:    Input Parameters:
1393: +  linesearch - linesearch context
1394: .  xnorm - The norm of the current solution
1395: .  fnorm - The norm of the current function
1396: -  ynorm - The norm of the current update

1398:    Level: advanced

1400: .seealso: SNESLineSearchGetNorms(), SNESLineSearchSetVecs()
1401: @*/
1402: PetscErrorCode  SNESLineSearchSetNorms(SNESLineSearch linesearch, PetscReal xnorm, PetscReal fnorm, PetscReal ynorm)
1403: {
1406:   linesearch->xnorm = xnorm;
1407:   linesearch->fnorm = fnorm;
1408:   linesearch->ynorm = ynorm;
1409:   return(0);
1410: }

1412: /*@
1413:    SNESLineSearchComputeNorms - Computes the norms of X, F, and Y.

1415:    Input Parameters:
1416: .  linesearch - linesearch context

1418:    Options Database Keys:
1419: .   -snes_linesearch_norms - turn norm computation on or off

1421:    Level: intermediate

1423: .seealso: SNESLineSearchGetNorms, SNESLineSearchSetNorms(), SNESLineSearchSetComputeNorms()
1424: @*/
1425: PetscErrorCode SNESLineSearchComputeNorms(SNESLineSearch linesearch)
1426: {
1428:   SNES           snes;

1431:   if (linesearch->norms) {
1432:     if (linesearch->ops->vinorm) {
1433:       SNESLineSearchGetSNES(linesearch, &snes);
1434:       VecNorm(linesearch->vec_sol, NORM_2, &linesearch->xnorm);
1435:       VecNorm(linesearch->vec_update, NORM_2, &linesearch->ynorm);
1436:       (*linesearch->ops->vinorm)(snes, linesearch->vec_func, linesearch->vec_sol, &linesearch->fnorm);
1437:     } else {
1438:       VecNormBegin(linesearch->vec_func,   NORM_2, &linesearch->fnorm);
1439:       VecNormBegin(linesearch->vec_sol,    NORM_2, &linesearch->xnorm);
1440:       VecNormBegin(linesearch->vec_update, NORM_2, &linesearch->ynorm);
1441:       VecNormEnd(linesearch->vec_func,     NORM_2, &linesearch->fnorm);
1442:       VecNormEnd(linesearch->vec_sol,      NORM_2, &linesearch->xnorm);
1443:       VecNormEnd(linesearch->vec_update,   NORM_2, &linesearch->ynorm);
1444:     }
1445:   }
1446:   return(0);
1447: }

1449: /*@
1450:    SNESLineSearchSetComputeNorms - Turns on or off the computation of final norms in the line search.

1452:    Input Parameters:
1453: +  linesearch  - linesearch context
1454: -  flg  - indicates whether or not to compute norms

1456:    Options Database Keys:
1457: .   -snes_linesearch_norms - turn norm computation on or off

1459:    Notes:
1460:    This is most relevant to the SNESLINESEARCHBASIC line search type.

1462:    Level: intermediate

1464: .seealso: SNESLineSearchGetNorms(), SNESLineSearchSetNorms(), SNESLineSearchComputeNorms(), SNESLINESEARCHBASIC
1465: @*/
1466: PetscErrorCode SNESLineSearchSetComputeNorms(SNESLineSearch linesearch, PetscBool flg)
1467: {
1469:   linesearch->norms = flg;
1470:   return(0);
1471: }

1473: /*@
1474:    SNESLineSearchGetVecs - Gets the vectors from the SNESLineSearch context

1476:    Input Parameters:
1477: .  linesearch - linesearch context

1479:    Output Parameters:
1480: +  X - Solution vector
1481: .  F - Function vector
1482: .  Y - Search direction vector
1483: .  W - Solution work vector
1484: -  G - Function work vector

1486:    Notes:
1487:    At the beginning of a line search application, X should contain a
1488:    solution and the vector F the function computed at X.  At the end of the
1489:    line search application, X should contain the new solution, and F the
1490:    function evaluated at the new solution.

1492:    These vectors are owned by the SNESLineSearch and should not be destroyed by the caller

1494:    Level: advanced

1496: .seealso: SNESLineSearchGetNorms(), SNESLineSearchSetVecs()
1497: @*/
1498: PetscErrorCode SNESLineSearchGetVecs(SNESLineSearch linesearch,Vec *X,Vec *F, Vec *Y,Vec *W,Vec *G)
1499: {
1502:   if (X) {
1504:     *X = linesearch->vec_sol;
1505:   }
1506:   if (F) {
1508:     *F = linesearch->vec_func;
1509:   }
1510:   if (Y) {
1512:     *Y = linesearch->vec_update;
1513:   }
1514:   if (W) {
1516:     *W = linesearch->vec_sol_new;
1517:   }
1518:   if (G) {
1520:     *G = linesearch->vec_func_new;
1521:   }
1522:   return(0);
1523: }

1525: /*@
1526:    SNESLineSearchSetVecs - Sets the vectors on the SNESLineSearch context

1528:    Input Parameters:
1529: +  linesearch - linesearch context
1530: .  X - Solution vector
1531: .  F - Function vector
1532: .  Y - Search direction vector
1533: .  W - Solution work vector
1534: -  G - Function work vector

1536:    Level: advanced

1538: .seealso: SNESLineSearchSetNorms(), SNESLineSearchGetVecs()
1539: @*/
1540: PetscErrorCode SNESLineSearchSetVecs(SNESLineSearch linesearch,Vec X,Vec F,Vec Y,Vec W, Vec G)
1541: {
1544:   if (X) {
1546:     linesearch->vec_sol = X;
1547:   }
1548:   if (F) {
1550:     linesearch->vec_func = F;
1551:   }
1552:   if (Y) {
1554:     linesearch->vec_update = Y;
1555:   }
1556:   if (W) {
1558:     linesearch->vec_sol_new = W;
1559:   }
1560:   if (G) {
1562:     linesearch->vec_func_new = G;
1563:   }
1564:   return(0);
1565: }

1567: /*@C
1568:    SNESLineSearchAppendOptionsPrefix - Appends to the prefix used for searching for all
1569:    SNES options in the database.

1571:    Logically Collective on SNESLineSearch

1573:    Input Parameters:
1574: +  snes - the SNES context
1575: -  prefix - the prefix to prepend to all option names

1577:    Notes:
1578:    A hyphen (-) must NOT be given at the beginning of the prefix name.
1579:    The first character of all runtime options is AUTOMATICALLY the hyphen.

1581:    Level: advanced

1583: .keywords: SNESLineSearch, append, options, prefix, database

1585: .seealso: SNESGetOptionsPrefix()
1586: @*/
1587: PetscErrorCode  SNESLineSearchAppendOptionsPrefix(SNESLineSearch linesearch,const char prefix[])
1588: {

1593:   PetscObjectAppendOptionsPrefix((PetscObject)linesearch,prefix);
1594:   return(0);
1595: }

1597: /*@C
1598:    SNESLineSearchGetOptionsPrefix - Sets the prefix used for searching for all
1599:    SNESLineSearch options in the database.

1601:    Not Collective

1603:    Input Parameter:
1604: .  linesearch - the SNESLineSearch context

1606:    Output Parameter:
1607: .  prefix - pointer to the prefix string used

1609:    Notes:
1610:    On the fortran side, the user should pass in a string 'prefix' of
1611:    sufficient length to hold the prefix.

1613:    Level: advanced

1615: .keywords: SNESLineSearch, get, options, prefix, database

1617: .seealso: SNESAppendOptionsPrefix()
1618: @*/
1619: PetscErrorCode  SNESLineSearchGetOptionsPrefix(SNESLineSearch linesearch,const char *prefix[])
1620: {

1625:   PetscObjectGetOptionsPrefix((PetscObject)linesearch,prefix);
1626:   return(0);
1627: }

1629: /*@C
1630:    SNESLineSearchSetWorkVecs - Gets work vectors for the line search.

1632:    Input Parameter:
1633: +  linesearch - the SNESLineSearch context
1634: -  nwork - the number of work vectors

1636:    Level: developer

1638:    Developers Note: This is PETSC_EXTERN because it may be used by user written plugin SNES implementations

1640: .keywords: SNESLineSearch, work, vector

1642: .seealso: SNESSetWorkVecs()
1643: @*/
1644: PetscErrorCode  SNESLineSearchSetWorkVecs(SNESLineSearch linesearch, PetscInt nwork)
1645: {

1649:   if (linesearch->vec_sol) {
1650:     VecDuplicateVecs(linesearch->vec_sol, nwork, &linesearch->work);
1651:   } else SETERRQ(PetscObjectComm((PetscObject)linesearch), PETSC_ERR_USER, "Cannot get linesearch work-vectors without setting a solution vec!");
1652:   return(0);
1653: }

1655: /*@
1656:    SNESLineSearchGetReason - Gets the success/failure status of the last line search application

1658:    Input Parameters:
1659: .  linesearch - linesearch context

1661:    Output Parameters:
1662: .  result - The success or failure status

1664:    Notes:
1665:    This is typically called after SNESLineSearchApply() in order to determine if the line-search failed
1666:    (and set the SNES convergence accordingly).

1668:    Level: intermediate

1670: .seealso: SNESLineSearchSetReason(), SNESLineSearchReason
1671: @*/
1672: PetscErrorCode  SNESLineSearchGetReason(SNESLineSearch linesearch, SNESLineSearchReason *result)
1673: {
1677:   *result = linesearch->result;
1678:   return(0);
1679: }

1681: /*@
1682:    SNESLineSearchSetReason - Sets the success/failure status of the last line search application

1684:    Input Parameters:
1685: +  linesearch - linesearch context
1686: -  result - The success or failure status

1688:    Notes:
1689:    This is typically called in a SNESLineSearchApply() or SNESLineSearchShell implementation to set
1690:    the success or failure of the line search method.

1692:    Level: developer

1694: .seealso: SNESLineSearchGetSResult()
1695: @*/
1696: PetscErrorCode  SNESLineSearchSetReason(SNESLineSearch linesearch, SNESLineSearchReason result)
1697: {
1700:   linesearch->result = result;
1701:   return(0);
1702: }

1704: /*@C
1705:    SNESLineSearchSetVIFunctions - Sets VI-specific functions for line search computation.

1707:    Input Parameters:
1708: +  snes - nonlinear context obtained from SNESCreate()
1709: .  projectfunc - function for projecting the function to the bounds
1710: -  normfunc - function for computing the norm of an active set

1712:    Logically Collective on SNES

1714:    Calling sequence of projectfunc:
1715: .vb
1716:    projectfunc (SNES snes, Vec X)
1717: .ve

1719:     Input parameters for projectfunc:
1720: +   snes - nonlinear context
1721: -   X - current solution

1723:     Output parameters for projectfunc:
1724: .   X - Projected solution

1726:    Calling sequence of normfunc:
1727: .vb
1728:    projectfunc (SNES snes, Vec X, Vec F, PetscScalar * fnorm)
1729: .ve

1731:     Input parameters for normfunc:
1732: +   snes - nonlinear context
1733: .   X - current solution
1734: -   F - current residual

1736:     Output parameters for normfunc:
1737: .   fnorm - VI-specific norm of the function

1739:     Notes:
1740:     The VI solvers require projection of the solution to the feasible set.  projectfunc should implement this.

1742:     The VI solvers require special evaluation of the function norm such that the norm is only calculated
1743:     on the inactive set.  This should be implemented by normfunc.

1745:     Level: developer

1747: .keywords: SNES, line search, VI, nonlinear, set, line search

1749: .seealso: SNESLineSearchGetVIFunctions(), SNESLineSearchSetPostCheck(), SNESLineSearchSetPreCheck()
1750: @*/
1751: extern PetscErrorCode SNESLineSearchSetVIFunctions(SNESLineSearch linesearch, SNESLineSearchVIProjectFunc projectfunc, SNESLineSearchVINormFunc normfunc)
1752: {
1755:   if (projectfunc) linesearch->ops->viproject = projectfunc;
1756:   if (normfunc) linesearch->ops->vinorm = normfunc;
1757:   return(0);
1758: }

1760: /*@C
1761:    SNESLineSearchGetVIFunctions - Sets VI-specific functions for line search computation.

1763:    Input Parameters:
1764: .  linesearch - the line search context, obtain with SNESGetLineSearch()

1766:    Output Parameters:
1767: +  projectfunc - function for projecting the function to the bounds
1768: -  normfunc - function for computing the norm of an active set

1770:    Logically Collective on SNES

1772:     Level: developer

1774: .keywords: SNES, line search, VI, nonlinear, get, line search

1776: .seealso: SNESLineSearchSetVIFunctions(), SNESLineSearchGetPostCheck(), SNESLineSearchGetPreCheck()
1777: @*/
1778: extern PetscErrorCode SNESLineSearchGetVIFunctions(SNESLineSearch linesearch, SNESLineSearchVIProjectFunc *projectfunc, SNESLineSearchVINormFunc *normfunc)
1779: {
1781:   if (projectfunc) *projectfunc = linesearch->ops->viproject;
1782:   if (normfunc) *normfunc = linesearch->ops->vinorm;
1783:   return(0);
1784: }

1786: /*@C
1787:   SNESLineSearchRegister - See SNESLineSearchRegister()

1789:   Level: advanced
1790: @*/
1791: PetscErrorCode  SNESLineSearchRegister(const char sname[],PetscErrorCode (*function)(SNESLineSearch))
1792: {

1796:   PetscFunctionListAdd(&SNESLineSearchList,sname,function);
1797:   return(0);
1798: }