Actual source code: taolinesearch.c

  1: #include <petsctaolinesearch.h>
  2: #include <petsc/private/taolinesearchimpl.h>

  4: PetscFunctionList TaoLineSearchList = NULL;

  6: PetscClassId TAOLINESEARCH_CLASSID = 0;

  8: PetscLogEvent TAOLINESEARCH_Apply;
  9: PetscLogEvent TAOLINESEARCH_Eval;

 11: const char *const TaoLineSearchConvergedReasons_Shifted[] = {"FAILED_ASCENT", "FAILED_BADPARAMETER", "FAILED_INFORNAN", "CONTINUE_ITERATING", "SUCCESS", "SUCCESS_USER", "HALTED_OTHER", "HALTED_MAXFCN", "HALTED_UPPERBOUND", "HALTED_LOWERBOUND", "HALTED_RTOL", "HALTED_USER", "TaoLineSearchConvergedReason", "TAOLINESEARCH_", NULL};
 12: const char *const *TaoLineSearchConvergedReasons = TaoLineSearchConvergedReasons_Shifted + 3;

 14: /*@
 15:   TaoLineSearchViewFromOptions - View a `TaoLineSearch` object based on values in the options database

 17:   Collective

 19:   Input Parameters:
 20: + A    - the `Tao` context
 21: . obj  - Optional object
 22: - name - command line option

 24:   Level: intermediate

 26:   Note:
 27:   See `PetscObjectViewFromOptions()` for available viewer options

 29: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchView()`, `PetscObjectViewFromOptions()`, `TaoLineSearchCreate()`
 30: @*/
 31: PetscErrorCode TaoLineSearchViewFromOptions(TaoLineSearch A, PetscObject obj, const char name[])
 32: {
 33:   PetscFunctionBegin;
 35:   PetscCall(PetscObjectViewFromOptions((PetscObject)A, obj, name));
 36:   PetscFunctionReturn(PETSC_SUCCESS);
 37: }

 39: /*@
 40:   TaoLineSearchView - Prints information about the `TaoLineSearch`

 42:   Collective

 44:   Input Parameters:
 45: + ls     - the `TaoLineSearch` context
 46: - viewer - visualization context

 48:   Options Database Key:
 49: . -tao_ls_view - Calls `TaoLineSearchView()` at the end of each line search

 51:   Level: beginner

 53:   Notes:
 54:   The available visualization contexts include
 55: +     `PETSC_VIEWER_STDOUT_SELF` - standard output (default)
 56: -     `PETSC_VIEWER_STDOUT_WORLD` - synchronized standard
 57:   output where only the first processor opens
 58:   the file.  All other processors send their
 59:   data to the first processor to print.

 61: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `PetscViewerASCIIOpen()`, `TaoLineSearchViewFromOptions()`
 62: @*/
 63: PetscErrorCode TaoLineSearchView(TaoLineSearch ls, PetscViewer viewer)
 64: {
 65:   PetscBool         isascii, isstring;
 66:   TaoLineSearchType type;

 68:   PetscFunctionBegin;
 70:   if (!viewer) PetscCall(PetscViewerASCIIGetStdout(((PetscObject)ls)->comm, &viewer));
 72:   PetscCheckSameComm(ls, 1, viewer, 2);

 74:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
 75:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSTRING, &isstring));
 76:   if (isascii) {
 77:     PetscCall(PetscObjectPrintClassNamePrefixType((PetscObject)ls, viewer));
 78:     PetscCall(PetscViewerASCIIPushTab(viewer));
 79:     PetscTryTypeMethod(ls, view, viewer);
 80:     PetscCall(PetscViewerASCIIPopTab(viewer));
 81:     PetscCall(PetscViewerASCIIPushTab(viewer));
 82:     PetscCall(PetscViewerASCIIPrintf(viewer, "maximum function evaluations=%" PetscInt_FMT "\n", ls->max_funcs));
 83:     PetscCall(PetscViewerASCIIPrintf(viewer, "tolerances: ftol=%g, rtol=%g, gtol=%g\n", (double)ls->ftol, (double)ls->rtol, (double)ls->gtol));
 84:     PetscCall(PetscViewerASCIIPrintf(viewer, "total number of function evaluations=%" PetscInt_FMT "\n", ls->nfeval));
 85:     PetscCall(PetscViewerASCIIPrintf(viewer, "total number of gradient evaluations=%" PetscInt_FMT "\n", ls->ngeval));
 86:     PetscCall(PetscViewerASCIIPrintf(viewer, "total number of function/gradient evaluations=%" PetscInt_FMT "\n", ls->nfgeval));

 88:     if (ls->bounded) PetscCall(PetscViewerASCIIPrintf(viewer, "using variable bounds\n"));
 89:     PetscCall(PetscViewerASCIIPrintf(viewer, "Termination reason: %s\n", TaoLineSearchConvergedReasons[ls->reason]));
 90:     PetscCall(PetscViewerASCIIPopTab(viewer));
 91:   } else if (isstring) {
 92:     PetscCall(TaoLineSearchGetType(ls, &type));
 93:     PetscCall(PetscViewerStringSPrintf(viewer, " %-3.3s", type));
 94:   }
 95:   PetscFunctionReturn(PETSC_SUCCESS);
 96: }

 98: /*@C
 99:   TaoLineSearchCreate - Creates a `TaoLineSearch` object.  Algorithms in `Tao` that use
100:   line-searches will automatically create one so this all is rarely needed

102:   Collective

104:   Input Parameter:
105: . comm - MPI communicator

107:   Output Parameter:
108: . newls - the new `TaoLineSearch` context

110:   Options Database Key:
111: . -tao_ls_type - select which method `Tao` should use

113:   Level: developer

115: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchType`, `TaoLineSearchSetType()`, `TaoLineSearchApply()`, `TaoLineSearchDestroy()`
116: @*/
117: PetscErrorCode TaoLineSearchCreate(MPI_Comm comm, TaoLineSearch *newls)
118: {
119:   TaoLineSearch ls;

121:   PetscFunctionBegin;
122:   PetscAssertPointer(newls, 2);
123:   PetscCall(TaoLineSearchInitializePackage());

125:   PetscCall(PetscHeaderCreate(ls, TAOLINESEARCH_CLASSID, "TaoLineSearch", "Linesearch", "Tao", comm, TaoLineSearchDestroy, TaoLineSearchView));
126:   ls->max_funcs = 30;
127:   ls->ftol      = 0.0001;
128:   ls->gtol      = 0.9;
129: #if defined(PETSC_USE_REAL_SINGLE)
130:   ls->rtol = 1.0e-5;
131: #else
132:   ls->rtol = 1.0e-10;
133: #endif
134:   ls->stepmin  = 1.0e-20;
135:   ls->stepmax  = 1.0e+20;
136:   ls->step     = 1.0;
137:   ls->initstep = 1.0;
138:   *newls       = ls;
139:   PetscFunctionReturn(PETSC_SUCCESS);
140: }

142: /*@
143:   TaoLineSearchSetUp - Sets up the internal data structures for the later use
144:   of a `TaoLineSearch`

146:   Collective

148:   Input Parameter:
149: . ls - the `TaoLineSearch` context

151:   Level: developer

153:   Note:
154:   The user will not need to explicitly call `TaoLineSearchSetUp()`, as it will
155:   automatically be called in `TaoLineSearchSolve()`.  However, if the user
156:   desires to call it explicitly, it should come after `TaoLineSearchCreate()`
157:   but before `TaoLineSearchApply()`.

159: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchCreate()`, `TaoLineSearchApply()`
160: @*/
161: PetscErrorCode TaoLineSearchSetUp(TaoLineSearch ls)
162: {
163:   const char *default_type = TAOLINESEARCHMT;
164:   PetscBool   flg;

166:   PetscFunctionBegin;
168:   if (ls->setupcalled) PetscFunctionReturn(PETSC_SUCCESS);
169:   if (!((PetscObject)ls)->type_name) PetscCall(TaoLineSearchSetType(ls, default_type));
170:   PetscTryTypeMethod(ls, setup);
171:   if (ls->usetaoroutines) {
172:     PetscCall(TaoIsObjectiveDefined(ls->tao, &flg));
173:     ls->hasobjective = flg;
174:     PetscCall(TaoIsGradientDefined(ls->tao, &flg));
175:     ls->hasgradient = flg;
176:     PetscCall(TaoIsObjectiveAndGradientDefined(ls->tao, &flg));
177:     ls->hasobjectiveandgradient = flg;
178:   } else {
179:     if (ls->ops->computeobjective) {
180:       ls->hasobjective = PETSC_TRUE;
181:     } else {
182:       ls->hasobjective = PETSC_FALSE;
183:     }
184:     if (ls->ops->computegradient) {
185:       ls->hasgradient = PETSC_TRUE;
186:     } else {
187:       ls->hasgradient = PETSC_FALSE;
188:     }
189:     if (ls->ops->computeobjectiveandgradient) {
190:       ls->hasobjectiveandgradient = PETSC_TRUE;
191:     } else {
192:       ls->hasobjectiveandgradient = PETSC_FALSE;
193:     }
194:   }
195:   ls->setupcalled = PETSC_TRUE;
196:   PetscFunctionReturn(PETSC_SUCCESS);
197: }

199: /*@
200:   TaoLineSearchReset - Some line searches may carry state information
201:   from one `TaoLineSearchApply()` to the next.  This function resets this
202:   state information.

204:   Collective

206:   Input Parameter:
207: . ls - the `TaoLineSearch` context

209:   Level: developer

211: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchCreate()`, `TaoLineSearchApply()`
212: @*/
213: PetscErrorCode TaoLineSearchReset(TaoLineSearch ls)
214: {
215:   PetscFunctionBegin;
217:   PetscTryTypeMethod(ls, reset);
218:   PetscFunctionReturn(PETSC_SUCCESS);
219: }

221: /*@
222:   TaoLineSearchDestroy - Destroys the `TaoLineSearch` context that was created with
223:   `TaoLineSearchCreate()`

225:   Collective

227:   Input Parameter:
228: . ls - the `TaoLineSearch` context

230:   Level: developer

232: .seealso: `TaoLineSearchCreate()`, `TaoLineSearchSolve()`
233: @*/
234: PetscErrorCode TaoLineSearchDestroy(TaoLineSearch *ls)
235: {
236:   PetscFunctionBegin;
237:   if (!*ls) PetscFunctionReturn(PETSC_SUCCESS);
239:   if (--((PetscObject)*ls)->refct > 0) {
240:     *ls = NULL;
241:     PetscFunctionReturn(PETSC_SUCCESS);
242:   }
243:   PetscCall(VecDestroy(&(*ls)->stepdirection));
244:   PetscCall(VecDestroy(&(*ls)->start_x));
245:   PetscCall(VecDestroy(&(*ls)->upper));
246:   PetscCall(VecDestroy(&(*ls)->lower));
247:   PetscTryTypeMethod(*ls, destroy);
248:   if ((*ls)->usemonitor) PetscCall(PetscViewerDestroy(&(*ls)->viewer));
249:   PetscCall(PetscHeaderDestroy(ls));
250:   PetscFunctionReturn(PETSC_SUCCESS);
251: }

253: /*@
254:   TaoLineSearchApply - Performs a line-search in a given step direction.
255:   Criteria for acceptable step length depends on the line-search algorithm chosen

257:   Collective

259:   Input Parameters:
260: + ls - the `TaoLineSearch` context
261: - s  - search direction

263:   Output Parameters:
264: + x          - On input the current solution, on output `x` contains the new solution determined by the line search
265: . f          - On input the objective function value at current solution, on output contains the objective function value at new solution
266: . g          - On input the gradient evaluated at `x`, on output contains the gradient at new solution
267: . steplength - scalar multiplier of s used ( x = x0 + steplength * x)
268: - reason     - `TaoLineSearchConvergedReason` reason why the line-search stopped

270:   Level: advanced

272:   Notes:
273:   The algorithm developer must set up the `TaoLineSearch` with calls to
274:   `TaoLineSearchSetObjectiveRoutine()` and `TaoLineSearchSetGradientRoutine()`,
275:   `TaoLineSearchSetObjectiveAndGradientRoutine()`, or `TaoLineSearchUseTaoRoutines()`.
276:   The latter is done automatically by default and thus requires no user input.

278:   You may or may not need to follow this with a call to
279:   `TaoAddLineSearchCounts()`, depending on whether you want these
280:   evaluations to count toward the total function/gradient evaluations.

282: .seealso: [](ch_tao), `Tao`, `TaoLineSearchConvergedReason`, `TaoLineSearch`, `TaoLineSearchCreate()`, `TaoLineSearchSetType()`,
283:           `TaoLineSearchSetInitialStepLength()`, `TaoAddLineSearchCounts()`
284: @*/
285: PetscErrorCode TaoLineSearchApply(TaoLineSearch ls, Vec x, PetscReal *f, Vec g, Vec s, PetscReal *steplength, TaoLineSearchConvergedReason *reason)
286: {
287:   PetscInt low1, low2, low3, high1, high2, high3;

289:   PetscFunctionBegin;
292:   PetscAssertPointer(f, 3);
295:   PetscAssertPointer(reason, 7);
296:   PetscCheckSameComm(ls, 1, x, 2);
297:   PetscCheckSameTypeAndComm(x, 2, g, 4);
298:   PetscCheckSameTypeAndComm(x, 2, s, 5);
299:   PetscCall(VecGetOwnershipRange(x, &low1, &high1));
300:   PetscCall(VecGetOwnershipRange(g, &low2, &high2));
301:   PetscCall(VecGetOwnershipRange(s, &low3, &high3));
302:   PetscCheck(low1 == low2 && low1 == low3 && high1 == high2 && high1 == high3, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Incompatible vector local lengths");

304:   *reason = TAOLINESEARCH_CONTINUE_ITERATING;
305:   PetscCall(PetscObjectReference((PetscObject)s));
306:   PetscCall(VecDestroy(&ls->stepdirection));
307:   ls->stepdirection = s;

309:   PetscCall(TaoLineSearchSetUp(ls));
310:   ls->nfeval  = 0;
311:   ls->ngeval  = 0;
312:   ls->nfgeval = 0;
313:   /* Check parameter values */
314:   if (ls->ftol < 0.0) {
315:     PetscCall(PetscInfo(ls, "Bad Line Search Parameter: ftol (%g) < 0\n", (double)ls->ftol));
316:     *reason = TAOLINESEARCH_FAILED_BADPARAMETER;
317:   }
318:   if (ls->rtol < 0.0) {
319:     PetscCall(PetscInfo(ls, "Bad Line Search Parameter: rtol (%g) < 0\n", (double)ls->rtol));
320:     *reason = TAOLINESEARCH_FAILED_BADPARAMETER;
321:   }
322:   if (ls->gtol < 0.0) {
323:     PetscCall(PetscInfo(ls, "Bad Line Search Parameter: gtol (%g) < 0\n", (double)ls->gtol));
324:     *reason = TAOLINESEARCH_FAILED_BADPARAMETER;
325:   }
326:   if (ls->stepmin < 0.0) {
327:     PetscCall(PetscInfo(ls, "Bad Line Search Parameter: stepmin (%g) < 0\n", (double)ls->stepmin));
328:     *reason = TAOLINESEARCH_FAILED_BADPARAMETER;
329:   }
330:   if (ls->stepmax < ls->stepmin) {
331:     PetscCall(PetscInfo(ls, "Bad Line Search Parameter: stepmin (%g) > stepmax (%g)\n", (double)ls->stepmin, (double)ls->stepmax));
332:     *reason = TAOLINESEARCH_FAILED_BADPARAMETER;
333:   }
334:   if (ls->max_funcs < 0) {
335:     PetscCall(PetscInfo(ls, "Bad Line Search Parameter: max_funcs (%" PetscInt_FMT ") < 0\n", ls->max_funcs));
336:     *reason = TAOLINESEARCH_FAILED_BADPARAMETER;
337:   }
338:   if (PetscIsInfOrNanReal(*f)) {
339:     PetscCall(PetscInfo(ls, "Initial Line Search Function Value is Inf or Nan (%g)\n", (double)*f));
340:     *reason = TAOLINESEARCH_FAILED_INFORNAN;
341:   }

343:   PetscCall(PetscObjectReference((PetscObject)x));
344:   PetscCall(VecDestroy(&ls->start_x));
345:   ls->start_x = x;

347:   PetscCall(PetscLogEventBegin(TAOLINESEARCH_Apply, ls, 0, 0, 0));
348:   PetscUseTypeMethod(ls, apply, x, f, g, s);
349:   PetscCall(PetscLogEventEnd(TAOLINESEARCH_Apply, ls, 0, 0, 0));
350:   *reason   = ls->reason;
351:   ls->new_f = *f;

353:   if (steplength) *steplength = ls->step;

355:   PetscCall(TaoLineSearchViewFromOptions(ls, NULL, "-tao_ls_view"));
356:   PetscFunctionReturn(PETSC_SUCCESS);
357: }

359: /*@
360:   TaoLineSearchSetType - Sets the algorithm used in a line search

362:   Collective

364:   Input Parameters:
365: + ls   - the `TaoLineSearch` context
366: - type - the `TaoLineSearchType` selection

368:   Options Database Key:
369: . -tao_ls_type <type> - select which method Tao should use at runtime

371:   Level: beginner

373: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchType`, `TaoLineSearchCreate()`, `TaoLineSearchGetType()`,
374:           `TaoLineSearchApply()`
375: @*/
376: PetscErrorCode TaoLineSearchSetType(TaoLineSearch ls, TaoLineSearchType type)
377: {
378:   PetscErrorCode (*r)(TaoLineSearch);
379:   PetscBool flg;

381:   PetscFunctionBegin;
383:   PetscAssertPointer(type, 2);
384:   PetscCall(PetscObjectTypeCompare((PetscObject)ls, type, &flg));
385:   if (flg) PetscFunctionReturn(PETSC_SUCCESS);

387:   PetscCall(PetscFunctionListFind(TaoLineSearchList, type, &r));
388:   PetscCheck(r, PetscObjectComm((PetscObject)ls), PETSC_ERR_ARG_UNKNOWN_TYPE, "Unable to find requested TaoLineSearch type %s", type);
389:   PetscTryTypeMethod(ls, destroy);
390:   ls->max_funcs = 30;
391:   ls->ftol      = 0.0001;
392:   ls->gtol      = 0.9;
393: #if defined(PETSC_USE_REAL_SINGLE)
394:   ls->rtol = 1.0e-5;
395: #else
396:   ls->rtol = 1.0e-10;
397: #endif
398:   ls->stepmin = 1.0e-20;
399:   ls->stepmax = 1.0e+20;

401:   ls->nfeval              = 0;
402:   ls->ngeval              = 0;
403:   ls->nfgeval             = 0;
404:   ls->ops->setup          = NULL;
405:   ls->ops->apply          = NULL;
406:   ls->ops->view           = NULL;
407:   ls->ops->setfromoptions = NULL;
408:   ls->ops->destroy        = NULL;
409:   ls->setupcalled         = PETSC_FALSE;
410:   PetscCall((*r)(ls));
411:   PetscCall(PetscObjectChangeTypeName((PetscObject)ls, type));
412:   PetscFunctionReturn(PETSC_SUCCESS);
413: }

415: /*@C
416:   TaoLineSearchMonitor - Monitor the line search steps. This routine will output the
417:   iteration number, step length, and function value before calling the implementation
418:   specific monitor.

420:   Input Parameters:
421: + ls   - the `TaoLineSearch` context
422: . its  - the current iterate number (>=0)
423: . f    - the current objective function value
424: - step - the step length

426:   Options Database Key:
427: . -tao_ls_monitor - Use the default monitor, which prints statistics to standard output

429:   Level: developer

431: .seealso: `TaoLineSearch`
432: @*/
433: PetscErrorCode TaoLineSearchMonitor(TaoLineSearch ls, PetscInt its, PetscReal f, PetscReal step)
434: {
435:   PetscInt tabs;

437:   PetscFunctionBegin;
439:   if (ls->usemonitor) {
440:     PetscCall(PetscViewerASCIIGetTab(ls->viewer, &tabs));
441:     PetscCall(PetscViewerASCIISetTab(ls->viewer, ((PetscObject)ls)->tablevel));
442:     PetscCall(PetscViewerASCIIPrintf(ls->viewer, "%3" PetscInt_FMT " LS", its));
443:     PetscCall(PetscViewerASCIIPrintf(ls->viewer, "  Function value: %g,", (double)f));
444:     PetscCall(PetscViewerASCIIPrintf(ls->viewer, "  Step length: %g\n", (double)step));
445:     if (ls->ops->monitor && its > 0) {
446:       PetscCall(PetscViewerASCIISetTab(ls->viewer, ((PetscObject)ls)->tablevel + 3));
447:       PetscUseTypeMethod(ls, monitor);
448:     }
449:     PetscCall(PetscViewerASCIISetTab(ls->viewer, tabs));
450:   }
451:   PetscFunctionReturn(PETSC_SUCCESS);
452: }

454: /*@
455:   TaoLineSearchSetFromOptions - Sets various `TaoLineSearch` parameters from user
456:   options.

458:   Collective

460:   Input Parameter:
461: . ls - the `TaoLineSearch` context

463:   Options Database Keys:
464: + -tao_ls_type <type>     - The algorithm that `TaoLineSearch` uses (more-thuente, gpcg, unit)
465: . -tao_ls_ftol <tol>      - tolerance for sufficient decrease
466: . -tao_ls_gtol <tol>      - tolerance for curvature condition
467: . -tao_ls_rtol <tol>      - relative tolerance for acceptable step
468: . -tao_ls_stepinit <step> - initial steplength allowed
469: . -tao_ls_stepmin <step>  - minimum steplength allowed
470: . -tao_ls_stepmax <step>  - maximum steplength allowed
471: . -tao_ls_max_funcs <n>   - maximum number of function evaluations allowed
472: - -tao_ls_view            - display line-search results to standard output

474:   Level: beginner

476: .seealso: `TaoLineSearch`
477: @*/
478: PetscErrorCode TaoLineSearchSetFromOptions(TaoLineSearch ls)
479: {
480:   const char *default_type = TAOLINESEARCHMT;
481:   char        type[256], monfilename[PETSC_MAX_PATH_LEN];
482:   PetscViewer monviewer;
483:   PetscBool   flg;

485:   PetscFunctionBegin;
487:   PetscObjectOptionsBegin((PetscObject)ls);
488:   if (((PetscObject)ls)->type_name) default_type = ((PetscObject)ls)->type_name;
489:   /* Check for type from options */
490:   PetscCall(PetscOptionsFList("-tao_ls_type", "Tao Line Search type", "TaoLineSearchSetType", TaoLineSearchList, default_type, type, 256, &flg));
491:   if (flg) {
492:     PetscCall(TaoLineSearchSetType(ls, type));
493:   } else if (!((PetscObject)ls)->type_name) {
494:     PetscCall(TaoLineSearchSetType(ls, default_type));
495:   }

497:   PetscCall(PetscOptionsInt("-tao_ls_max_funcs", "max function evals in line search", "", ls->max_funcs, &ls->max_funcs, NULL));
498:   PetscCall(PetscOptionsReal("-tao_ls_ftol", "tol for sufficient decrease", "", ls->ftol, &ls->ftol, NULL));
499:   PetscCall(PetscOptionsReal("-tao_ls_gtol", "tol for curvature condition", "", ls->gtol, &ls->gtol, NULL));
500:   PetscCall(PetscOptionsReal("-tao_ls_rtol", "relative tol for acceptable step", "", ls->rtol, &ls->rtol, NULL));
501:   PetscCall(PetscOptionsReal("-tao_ls_stepmin", "lower bound for step", "", ls->stepmin, &ls->stepmin, NULL));
502:   PetscCall(PetscOptionsReal("-tao_ls_stepmax", "upper bound for step", "", ls->stepmax, &ls->stepmax, NULL));
503:   PetscCall(PetscOptionsReal("-tao_ls_stepinit", "initial step", "", ls->initstep, &ls->initstep, NULL));
504:   PetscCall(PetscOptionsString("-tao_ls_monitor", "enable the basic monitor", "TaoLineSearchSetMonitor", "stdout", monfilename, sizeof(monfilename), &flg));
505:   if (flg) {
506:     PetscCall(PetscViewerASCIIOpen(PetscObjectComm((PetscObject)ls), monfilename, &monviewer));
507:     ls->viewer     = monviewer;
508:     ls->usemonitor = PETSC_TRUE;
509:   }
510:   PetscTryTypeMethod(ls, setfromoptions, PetscOptionsObject);
511:   PetscOptionsEnd();
512:   PetscFunctionReturn(PETSC_SUCCESS);
513: }

515: /*@
516:   TaoLineSearchGetType - Gets the current line search algorithm

518:   Not Collective

520:   Input Parameter:
521: . ls - the `TaoLineSearch` context

523:   Output Parameter:
524: . type - the line search algorithm in effect

526:   Level: developer

528: .seealso: `TaoLineSearch`
529: @*/
530: PetscErrorCode TaoLineSearchGetType(TaoLineSearch ls, TaoLineSearchType *type)
531: {
532:   PetscFunctionBegin;
534:   PetscAssertPointer(type, 2);
535:   *type = ((PetscObject)ls)->type_name;
536:   PetscFunctionReturn(PETSC_SUCCESS);
537: }

539: /*@
540:   TaoLineSearchGetNumberFunctionEvaluations - Gets the number of function and gradient evaluation
541:   routines used by the line search in last application (not cumulative).

543:   Not Collective

545:   Input Parameter:
546: . ls - the `TaoLineSearch` context

548:   Output Parameters:
549: + nfeval  - number of function evaluations
550: . ngeval  - number of gradient evaluations
551: - nfgeval - number of function/gradient evaluations

553:   Level: intermediate

555:   Note:
556:   If the line search is using the `Tao` objective and gradient
557:   routines directly (see `TaoLineSearchUseTaoRoutines()`), then the `Tao`
558:   is already counting the number of evaluations.

560: .seealso: `TaoLineSearch`
561: @*/
562: PetscErrorCode TaoLineSearchGetNumberFunctionEvaluations(TaoLineSearch ls, PetscInt *nfeval, PetscInt *ngeval, PetscInt *nfgeval)
563: {
564:   PetscFunctionBegin;
566:   *nfeval  = ls->nfeval;
567:   *ngeval  = ls->ngeval;
568:   *nfgeval = ls->nfgeval;
569:   PetscFunctionReturn(PETSC_SUCCESS);
570: }

572: /*@
573:   TaoLineSearchIsUsingTaoRoutines - Checks whether the line search is using
574:   the standard `Tao` evaluation routines.

576:   Not Collective

578:   Input Parameter:
579: . ls - the `TaoLineSearch` context

581:   Output Parameter:
582: . flg - `PETSC_TRUE` if the line search is using `Tao` evaluation routines,
583:         otherwise `PETSC_FALSE`

585:   Level: developer

587: .seealso: `TaoLineSearch`
588: @*/
589: PetscErrorCode TaoLineSearchIsUsingTaoRoutines(TaoLineSearch ls, PetscBool *flg)
590: {
591:   PetscFunctionBegin;
593:   *flg = ls->usetaoroutines;
594:   PetscFunctionReturn(PETSC_SUCCESS);
595: }

597: /*@C
598:   TaoLineSearchSetObjectiveRoutine - Sets the function evaluation routine for the line search

600:   Logically Collective

602:   Input Parameters:
603: + ls   - the `TaoLineSearch` context
604: . func - the objective function evaluation routine
605: - ctx  - the (optional) user-defined context for private data

607:   Calling sequence of `func`:
608: + ls  - the line search context
609: . x   - input vector
610: . f   - function value
611: - ctx - (optional) user-defined context

613:   Level: advanced

615:   Notes:
616:   Use this routine only if you want the line search objective
617:   evaluation routine to be different from the `Tao`'s objective
618:   evaluation routine. If you use this routine you must also set
619:   the line search gradient and/or function/gradient routine.

621:   Some algorithms (lcl, gpcg) set their own objective routine for the
622:   line search, application programmers should be wary of overriding the
623:   default objective routine.

625: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchCreate()`, `TaoLineSearchSetGradientRoutine()`, `TaoLineSearchSetObjectiveAndGradientRoutine()`, `TaoLineSearchUseTaoRoutines()`
626: @*/
627: PetscErrorCode TaoLineSearchSetObjectiveRoutine(TaoLineSearch ls, PetscErrorCode (*func)(TaoLineSearch ls, Vec x, PetscReal *f, void *ctx), void *ctx)
628: {
629:   PetscFunctionBegin;

632:   ls->ops->computeobjective = func;
633:   if (ctx) ls->userctx_func = ctx;
634:   ls->usetaoroutines = PETSC_FALSE;
635:   PetscFunctionReturn(PETSC_SUCCESS);
636: }

638: /*@C
639:   TaoLineSearchSetGradientRoutine - Sets the gradient evaluation routine for the line search

641:   Logically Collective

643:   Input Parameters:
644: + ls   - the `TaoLineSearch` context
645: . func - the gradient evaluation routine
646: - ctx  - the (optional) user-defined context for private data

648:   Calling sequence of `func`:
649: + ls  - the linesearch object
650: . x   - input vector
651: . g   - gradient vector
652: - ctx - (optional) user-defined context

654:   Level: beginner

656:   Note:
657:   Use this routine only if you want the line search gradient
658:   evaluation routine to be different from the `Tao`'s gradient
659:   evaluation routine. If you use this routine you must also set
660:   the line search function and/or function/gradient routine.

662:   Some algorithms (lcl, gpcg) set their own gradient routine for the
663:   line search, application programmers should be wary of overriding the
664:   default gradient routine.

666: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchCreate()`, `TaoLineSearchSetObjectiveRoutine()`, `TaoLineSearchSetObjectiveAndGradientRoutine()`, `TaoLineSearchUseTaoRoutines()`
667: @*/
668: PetscErrorCode TaoLineSearchSetGradientRoutine(TaoLineSearch ls, PetscErrorCode (*func)(TaoLineSearch ls, Vec x, Vec g, void *ctx), void *ctx)
669: {
670:   PetscFunctionBegin;
672:   ls->ops->computegradient = func;
673:   if (ctx) ls->userctx_grad = ctx;
674:   ls->usetaoroutines = PETSC_FALSE;
675:   PetscFunctionReturn(PETSC_SUCCESS);
676: }

678: /*@C
679:   TaoLineSearchSetObjectiveAndGradientRoutine - Sets the objective/gradient evaluation routine for the line search

681:   Logically Collective

683:   Input Parameters:
684: + ls   - the `TaoLineSearch` context
685: . func - the objective and gradient evaluation routine
686: - ctx  - the (optional) user-defined context for private data

688:   Calling sequence of `func`:
689: + ls  - the linesearch object
690: . x   - input vector
691: . f   - function value
692: . g   - gradient vector
693: - ctx - (optional) user-defined context

695:   Level: beginner

697:   Note:
698:   Use this routine only if you want the line search objective and gradient
699:   evaluation routines to be different from the `Tao`'s objective
700:   and gradient evaluation routines.

702:   Some algorithms (lcl, gpcg) set their own objective routine for the
703:   line search, application programmers should be wary of overriding the
704:   default objective routine.

706: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchCreate()`, `TaoLineSearchSetObjectiveRoutine()`, `TaoLineSearchSetGradientRoutine()`, `TaoLineSearchUseTaoRoutines()`
707: @*/
708: PetscErrorCode TaoLineSearchSetObjectiveAndGradientRoutine(TaoLineSearch ls, PetscErrorCode (*func)(TaoLineSearch ls, Vec x, PetscReal *f, Vec g, void *ctx), void *ctx)
709: {
710:   PetscFunctionBegin;
712:   ls->ops->computeobjectiveandgradient = func;
713:   if (ctx) ls->userctx_funcgrad = ctx;
714:   ls->usetaoroutines = PETSC_FALSE;
715:   PetscFunctionReturn(PETSC_SUCCESS);
716: }

718: /*@C
719:   TaoLineSearchSetObjectiveAndGTSRoutine - Sets the objective and
720:   (gradient'*stepdirection) evaluation routine for the line search.

722:   Logically Collective

724:   Input Parameters:
725: + ls   - the `TaoLineSearch` context
726: . func - the objective and gradient evaluation routine
727: - ctx  - the (optional) user-defined context for private data

729:   Calling sequence of `func`:
730: + ls  - the linesearch context
731: . x   - input vector
732: . s   - step direction
733: . f   - function value
734: . gts - inner product of gradient and step direction vectors
735: - ctx - (optional) user-defined context

737:   Level: advanced

739:   Notes:
740:   Sometimes it is more efficient to compute the inner product of the gradient and the step
741:   direction than it is to compute the gradient, and this is all the line search typically needs
742:   of the gradient.

744:   The gradient will still need to be computed at the end of the line
745:   search, so you will still need to set a line search gradient evaluation
746:   routine

748:   Bounded line searches (those used in bounded optimization algorithms)
749:   don't use g's directly, but rather (g'x - g'x0)/steplength.  You can get the
750:   x0 and steplength with `TaoLineSearchGetStartingVector()` and `TaoLineSearchGetStepLength()`

752:   Some algorithms (lcl, gpcg) set their own objective routine for the
753:   line search, application programmers should be wary of overriding the
754:   default objective routine.

756: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchCreate()`, `TaoLineSearchSetObjective()`, `TaoLineSearchSetGradient()`, `TaoLineSearchUseTaoRoutines()`
757: @*/
758: PetscErrorCode TaoLineSearchSetObjectiveAndGTSRoutine(TaoLineSearch ls, PetscErrorCode (*func)(TaoLineSearch ls, Vec x, Vec s, PetscReal *f, PetscReal *gts, void *ctx), void *ctx)
759: {
760:   PetscFunctionBegin;
762:   ls->ops->computeobjectiveandgts = func;
763:   if (ctx) ls->userctx_funcgts = ctx;
764:   ls->usegts         = PETSC_TRUE;
765:   ls->usetaoroutines = PETSC_FALSE;
766:   PetscFunctionReturn(PETSC_SUCCESS);
767: }

769: /*@
770:   TaoLineSearchUseTaoRoutines - Informs the `TaoLineSearch` to use the
771:   objective and gradient evaluation routines from the given `Tao` object. The default.

773:   Logically Collective

775:   Input Parameters:
776: + ls - the `TaoLineSearch` context
777: - ts - the `Tao` context with defined objective/gradient evaluation routines

779:   Level: developer

781: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchCreate()`
782: @*/
783: PetscErrorCode TaoLineSearchUseTaoRoutines(TaoLineSearch ls, Tao ts)
784: {
785:   PetscFunctionBegin;
788:   ls->tao            = ts;
789:   ls->usetaoroutines = PETSC_TRUE;
790:   PetscFunctionReturn(PETSC_SUCCESS);
791: }

793: /*@
794:   TaoLineSearchComputeObjective - Computes the objective function value at a given point

796:   Collective

798:   Input Parameters:
799: + ls - the `TaoLineSearch` context
800: - x  - input vector

802:   Output Parameter:
803: . f - Objective value at `x`

805:   Level: developer

807:   Note:
808:   `TaoLineSearchComputeObjective()` is typically used within line searches
809:   so most users would not generally call this routine themselves.

811: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchComputeGradient()`, `TaoLineSearchComputeObjectiveAndGradient()`, `TaoLineSearchSetObjectiveRoutine()`
812: @*/
813: PetscErrorCode TaoLineSearchComputeObjective(TaoLineSearch ls, Vec x, PetscReal *f)
814: {
815:   Vec       gdummy;
816:   PetscReal gts;

818:   PetscFunctionBegin;
821:   PetscAssertPointer(f, 3);
822:   PetscCheckSameComm(ls, 1, x, 2);
823:   if (ls->usetaoroutines) {
824:     PetscCall(TaoComputeObjective(ls->tao, x, f));
825:   } else {
826:     PetscCheck(ls->ops->computeobjective || ls->ops->computeobjectiveandgradient || ls->ops->computeobjectiveandgts, PetscObjectComm((PetscObject)ls), PETSC_ERR_ARG_WRONGSTATE, "Line Search does not have objective function set");
827:     PetscCall(PetscLogEventBegin(TAOLINESEARCH_Eval, ls, 0, 0, 0));
828:     if (ls->ops->computeobjective) PetscCallBack("TaoLineSearch callback objective", (*ls->ops->computeobjective)(ls, x, f, ls->userctx_func));
829:     else if (ls->ops->computeobjectiveandgradient) {
830:       PetscCall(VecDuplicate(x, &gdummy));
831:       PetscCallBack("TaoLineSearch callback objective", (*ls->ops->computeobjectiveandgradient)(ls, x, f, gdummy, ls->userctx_funcgrad));
832:       PetscCall(VecDestroy(&gdummy));
833:     } else PetscCallBack("TaoLineSearch callback objective", (*ls->ops->computeobjectiveandgts)(ls, x, ls->stepdirection, f, &gts, ls->userctx_funcgts));
834:     PetscCall(PetscLogEventEnd(TAOLINESEARCH_Eval, ls, 0, 0, 0));
835:   }
836:   ls->nfeval++;
837:   PetscFunctionReturn(PETSC_SUCCESS);
838: }

840: /*@
841:   TaoLineSearchComputeObjectiveAndGradient - Computes the objective function value at a given point

843:   Collective

845:   Input Parameters:
846: + ls - the `TaoLineSearch` context
847: - x  - input vector

849:   Output Parameters:
850: + f - Objective value at `x`
851: - g - Gradient vector at `x`

853:   Level: developer

855:   Note:
856:   `TaoLineSearchComputeObjectiveAndGradient()` is typically used within line searches
857:   so most users would not generally call this routine themselves.

859: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchComputeGradient()`, `TaoLineSearchSetObjectiveRoutine()`
860: @*/
861: PetscErrorCode TaoLineSearchComputeObjectiveAndGradient(TaoLineSearch ls, Vec x, PetscReal *f, Vec g)
862: {
863:   PetscFunctionBegin;
866:   PetscAssertPointer(f, 3);
868:   PetscCheckSameComm(ls, 1, x, 2);
869:   PetscCheckSameComm(ls, 1, g, 4);
870:   if (ls->usetaoroutines) {
871:     PetscCall(TaoComputeObjectiveAndGradient(ls->tao, x, f, g));
872:   } else {
873:     PetscCall(PetscLogEventBegin(TAOLINESEARCH_Eval, ls, 0, 0, 0));
874:     if (ls->ops->computeobjectiveandgradient) PetscCallBack("TaoLineSearch callback objective/gradient", (*ls->ops->computeobjectiveandgradient)(ls, x, f, g, ls->userctx_funcgrad));
875:     else {
876:       PetscCallBack("TaoLineSearch callback objective", (*ls->ops->computeobjective)(ls, x, f, ls->userctx_func));
877:       PetscCallBack("TaoLineSearch callback gradient", (*ls->ops->computegradient)(ls, x, g, ls->userctx_grad));
878:     }
879:     PetscCall(PetscLogEventEnd(TAOLINESEARCH_Eval, ls, 0, 0, 0));
880:     PetscCall(PetscInfo(ls, "TaoLineSearch Function evaluation: %14.12e\n", (double)(*f)));
881:   }
882:   ls->nfgeval++;
883:   PetscFunctionReturn(PETSC_SUCCESS);
884: }

886: /*@
887:   TaoLineSearchComputeGradient - Computes the gradient of the objective function

889:   Collective

891:   Input Parameters:
892: + ls - the `TaoLineSearch` context
893: - x  - input vector

895:   Output Parameter:
896: . g - gradient vector

898:   Level: developer

900:   Note:
901:   `TaoComputeGradient()` is typically used within line searches
902:   so most users would not generally call this routine themselves.

904: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchComputeObjective()`, `TaoLineSearchComputeObjectiveAndGradient()`, `TaoLineSearchSetGradient()`
905: @*/
906: PetscErrorCode TaoLineSearchComputeGradient(TaoLineSearch ls, Vec x, Vec g)
907: {
908:   PetscReal fdummy;

910:   PetscFunctionBegin;
914:   PetscCheckSameComm(ls, 1, x, 2);
915:   PetscCheckSameComm(ls, 1, g, 3);
916:   if (ls->usetaoroutines) {
917:     PetscCall(TaoComputeGradient(ls->tao, x, g));
918:   } else {
919:     PetscCall(PetscLogEventBegin(TAOLINESEARCH_Eval, ls, 0, 0, 0));
920:     if (ls->ops->computegradient) PetscCallBack("TaoLineSearch callback gradient", (*ls->ops->computegradient)(ls, x, g, ls->userctx_grad));
921:     else PetscCallBack("TaoLineSearch callback gradient", (*ls->ops->computeobjectiveandgradient)(ls, x, &fdummy, g, ls->userctx_funcgrad));
922:     PetscCall(PetscLogEventEnd(TAOLINESEARCH_Eval, ls, 0, 0, 0));
923:   }
924:   ls->ngeval++;
925:   PetscFunctionReturn(PETSC_SUCCESS);
926: }

928: /*@
929:   TaoLineSearchComputeObjectiveAndGTS - Computes the objective function value and inner product of gradient and
930:   step direction at a given point

932:   Collective

934:   Input Parameters:
935: + ls - the `TaoLineSearch` context
936: - x  - input vector

938:   Output Parameters:
939: + f   - Objective value at `x`
940: - gts - inner product of gradient and step direction at `x`

942:   Level: developer

944:   Note:
945:   `TaoLineSearchComputeObjectiveAndGTS()` is typically used within line searches
946:   so most users would not generally call this routine themselves.

948: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchComputeGradient()`, `TaoLineSearchComputeObjectiveAndGradient()`, `TaoLineSearchSetObjectiveRoutine()`
949: @*/
950: PetscErrorCode TaoLineSearchComputeObjectiveAndGTS(TaoLineSearch ls, Vec x, PetscReal *f, PetscReal *gts)
951: {
952:   PetscFunctionBegin;
955:   PetscAssertPointer(f, 3);
956:   PetscAssertPointer(gts, 4);
957:   PetscCheckSameComm(ls, 1, x, 2);
958:   PetscCall(PetscLogEventBegin(TAOLINESEARCH_Eval, ls, 0, 0, 0));
959:   PetscCallBack("TaoLineSearch callback objective/gts", (*ls->ops->computeobjectiveandgts)(ls, x, ls->stepdirection, f, gts, ls->userctx_funcgts));
960:   PetscCall(PetscLogEventEnd(TAOLINESEARCH_Eval, ls, 0, 0, 0));
961:   PetscCall(PetscInfo(ls, "TaoLineSearch Function evaluation: %14.12e\n", (double)(*f)));
962:   ls->nfeval++;
963:   PetscFunctionReturn(PETSC_SUCCESS);
964: }

966: /*@
967:   TaoLineSearchGetSolution - Returns the solution to the line search

969:   Collective

971:   Input Parameter:
972: . ls - the `TaoLineSearch` context

974:   Output Parameters:
975: + x          - the new solution
976: . f          - the objective function value at `x`
977: . g          - the gradient at `x`
978: . steplength - the multiple of the step direction taken by the line search
979: - reason     - the reason why the line search terminated

981:   Level: developer

983: .seealso: `TaoLineSearchGetStartingVector()`, `TaoLineSearchGetStepDirection()`
984: @*/
985: PetscErrorCode TaoLineSearchGetSolution(TaoLineSearch ls, Vec x, PetscReal *f, Vec g, PetscReal *steplength, TaoLineSearchConvergedReason *reason)
986: {
987:   PetscFunctionBegin;
990:   PetscAssertPointer(f, 3);
992:   PetscAssertPointer(reason, 6);
993:   if (ls->new_x) PetscCall(VecCopy(ls->new_x, x));
994:   *f = ls->new_f;
995:   if (ls->new_g) PetscCall(VecCopy(ls->new_g, g));
996:   if (steplength) *steplength = ls->step;
997:   *reason = ls->reason;
998:   PetscFunctionReturn(PETSC_SUCCESS);
999: }

1001: /*@
1002:   TaoLineSearchGetStartingVector - Gets a the initial point of the line
1003:   search.

1005:   Not Collective

1007:   Input Parameter:
1008: . ls - the `TaoLineSearch` context

1010:   Output Parameter:
1011: . x - The initial point of the line search

1013:   Level: advanced

1015: .seealso: `TaoLineSearchGetSolution()`, `TaoLineSearchGetStepDirection()`
1016: @*/
1017: PetscErrorCode TaoLineSearchGetStartingVector(TaoLineSearch ls, Vec *x)
1018: {
1019:   PetscFunctionBegin;
1021:   if (x) *x = ls->start_x;
1022:   PetscFunctionReturn(PETSC_SUCCESS);
1023: }

1025: /*@
1026:   TaoLineSearchGetStepDirection - Gets the step direction of the line
1027:   search.

1029:   Not Collective

1031:   Input Parameter:
1032: . ls - the `TaoLineSearch` context

1034:   Output Parameter:
1035: . s - the step direction of the line search

1037:   Level: advanced

1039: .seealso: `TaoLineSearchGetSolution()`, `TaoLineSearchGetStartingVector()`
1040: @*/
1041: PetscErrorCode TaoLineSearchGetStepDirection(TaoLineSearch ls, Vec *s)
1042: {
1043:   PetscFunctionBegin;
1045:   if (s) *s = ls->stepdirection;
1046:   PetscFunctionReturn(PETSC_SUCCESS);
1047: }

1049: /*@
1050:   TaoLineSearchGetFullStepObjective - Returns the objective function value at the full step.  Useful for some minimization algorithms.

1052:   Not Collective

1054:   Input Parameter:
1055: . ls - the `TaoLineSearch` context

1057:   Output Parameter:
1058: . f_fullstep - the objective value at the full step length

1060:   Level: developer

1062: .seealso: `TaoLineSearchGetSolution()`, `TaoLineSearchGetStartingVector()`, `TaoLineSearchGetStepDirection()`
1063: @*/
1064: PetscErrorCode TaoLineSearchGetFullStepObjective(TaoLineSearch ls, PetscReal *f_fullstep)
1065: {
1066:   PetscFunctionBegin;
1068:   *f_fullstep = ls->f_fullstep;
1069:   PetscFunctionReturn(PETSC_SUCCESS);
1070: }

1072: /*@
1073:   TaoLineSearchSetVariableBounds - Sets the upper and lower bounds for a bounded line search

1075:   Logically Collective

1077:   Input Parameters:
1078: + ls - the `TaoLineSearch` context
1079: . xl - vector of lower bounds
1080: - xu - vector of upper bounds

1082:   Level: beginner

1084:   Note:
1085:   If the variable bounds are not set with this routine, then
1086:   `PETSC_NINFINITY` and `PETSC_INFINITY` are assumed

1088: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoSetVariableBounds()`, `TaoLineSearchCreate()`
1089: @*/
1090: PetscErrorCode TaoLineSearchSetVariableBounds(TaoLineSearch ls, Vec xl, Vec xu)
1091: {
1092:   PetscFunctionBegin;
1096:   PetscCall(PetscObjectReference((PetscObject)xl));
1097:   PetscCall(PetscObjectReference((PetscObject)xu));
1098:   PetscCall(VecDestroy(&ls->lower));
1099:   PetscCall(VecDestroy(&ls->upper));
1100:   ls->lower   = xl;
1101:   ls->upper   = xu;
1102:   ls->bounded = (PetscBool)(xl || xu);
1103:   PetscFunctionReturn(PETSC_SUCCESS);
1104: }

1106: /*@
1107:   TaoLineSearchSetInitialStepLength - Sets the initial step length of a line
1108:   search.  If this value is not set then 1.0 is assumed.

1110:   Logically Collective

1112:   Input Parameters:
1113: + ls - the `TaoLineSearch` context
1114: - s  - the initial step size

1116:   Level: intermediate

1118: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchGetStepLength()`, `TaoLineSearchApply()`
1119: @*/
1120: PetscErrorCode TaoLineSearchSetInitialStepLength(TaoLineSearch ls, PetscReal s)
1121: {
1122:   PetscFunctionBegin;
1125:   ls->initstep = s;
1126:   PetscFunctionReturn(PETSC_SUCCESS);
1127: }

1129: /*@
1130:   TaoLineSearchGetStepLength - Get the current step length

1132:   Not Collective

1134:   Input Parameter:
1135: . ls - the `TaoLineSearch` context

1137:   Output Parameter:
1138: . s - the current step length

1140:   Level: intermediate

1142: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchSetInitialStepLength()`, `TaoLineSearchApply()`
1143: @*/
1144: PetscErrorCode TaoLineSearchGetStepLength(TaoLineSearch ls, PetscReal *s)
1145: {
1146:   PetscFunctionBegin;
1148:   *s = ls->step;
1149:   PetscFunctionReturn(PETSC_SUCCESS);
1150: }

1152: /*@C
1153:   TaoLineSearchRegister - Adds a line-search algorithm to the registry

1155:   Not Collective, No Fortran Support

1157:   Input Parameters:
1158: + sname - name of a new user-defined solver
1159: - func  - routine to Create method context

1161:   Example Usage:
1162: .vb
1163:    TaoLineSearchRegister("my_linesearch", MyLinesearchCreate);
1164: .ve

1166:   Then, your solver can be chosen with the procedural interface via
1167: .vb
1168:   TaoLineSearchSetType(ls, "my_linesearch")
1169: .ve
1170:   or at runtime via the option
1171: .vb
1172:   -tao_ls_type my_linesearch
1173: .ve

1175:   Level: developer

1177:   Note:
1178:   `TaoLineSearchRegister()` may be called multiple times to add several user-defined solvers.

1180: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`
1181: @*/
1182: PetscErrorCode TaoLineSearchRegister(const char sname[], PetscErrorCode (*func)(TaoLineSearch))
1183: {
1184:   PetscFunctionBegin;
1185:   PetscCall(TaoLineSearchInitializePackage());
1186:   PetscCall(PetscFunctionListAdd(&TaoLineSearchList, sname, func));
1187:   PetscFunctionReturn(PETSC_SUCCESS);
1188: }

1190: /*@
1191:   TaoLineSearchAppendOptionsPrefix - Appends to the prefix used for searching
1192:   for all `TaoLineSearch` options in the database.

1194:   Collective

1196:   Input Parameters:
1197: + ls - the `TaoLineSearch` solver context
1198: - p  - the prefix string to prepend to all line search requests

1200:   Level: advanced

1202:   Notes:
1203:   A hyphen (-) must NOT be given at the beginning of the prefix name.
1204:   The first character of all runtime options is AUTOMATICALLY the hyphen.

1206:   This is inherited from the `Tao` object so rarely needs to be set

1208: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchSetOptionsPrefix()`, `TaoLineSearchGetOptionsPrefix()`
1209: @*/
1210: PetscErrorCode TaoLineSearchAppendOptionsPrefix(TaoLineSearch ls, const char p[])
1211: {
1212:   return PetscObjectAppendOptionsPrefix((PetscObject)ls, p);
1213: }

1215: /*@
1216:   TaoLineSearchGetOptionsPrefix - Gets the prefix used for searching for all
1217:   `TaoLineSearch` options in the database

1219:   Not Collective

1221:   Input Parameter:
1222: . ls - the `TaoLineSearch` context

1224:   Output Parameter:
1225: . p - pointer to the prefix string used is returned

1227:   Level: advanced

1229: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchSetOptionsPrefix()`, `TaoLineSearchAppendOptionsPrefix()`
1230: @*/
1231: PetscErrorCode TaoLineSearchGetOptionsPrefix(TaoLineSearch ls, const char *p[])
1232: {
1233:   return PetscObjectGetOptionsPrefix((PetscObject)ls, p);
1234: }

1236: /*@
1237:   TaoLineSearchSetOptionsPrefix - Sets the prefix used for searching for all
1238:   `TaoLineSearch` options in the database.

1240:   Logically Collective

1242:   Input Parameters:
1243: + ls - the `TaoLineSearch` context
1244: - p  - the prefix string to prepend to all `ls` option requests

1246:   Level: advanced

1248:   Notes:
1249:   A hyphen (-) must NOT be given at the beginning of the prefix name.
1250:   The first character of all runtime options is AUTOMATICALLY the hyphen.

1252:   This is inherited from the `Tao` object so rarely needs to be set

1254:   For example, to distinguish between the runtime options for two
1255:   different line searches, one could call
1256: .vb
1257:       TaoLineSearchSetOptionsPrefix(ls1,"sys1_")
1258:       TaoLineSearchSetOptionsPrefix(ls2,"sys2_")
1259: .ve

1261:   This would enable use of different options for each system, such as
1262: .vb
1263:       -sys1_tao_ls_type mt
1264:       -sys2_tao_ls_type armijo
1265: .ve

1267: .seealso: [](ch_tao), `Tao`, `TaoLineSearch`, `TaoLineSearchAppendOptionsPrefix()`, `TaoLineSearchGetOptionsPrefix()`
1268: @*/
1269: PetscErrorCode TaoLineSearchSetOptionsPrefix(TaoLineSearch ls, const char p[])
1270: {
1271:   return PetscObjectSetOptionsPrefix((PetscObject)ls, p);
1272: }