Actual source code: nepopts.c
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain
6: This file is part of SLEPc.
7: SLEPc is distributed under a 2-clause BSD license (see LICENSE).
8: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
9: */
10: /*
11: NEP routines related to options that can be set via the command-line
12: or procedurally
13: */
15: #include <slepc/private/nepimpl.h>
16: #include <petscdraw.h>
18: /*@C
19: NEPMonitorSetFromOptions - Sets a monitor function and viewer appropriate for the type
20: indicated by the user.
22: Collective
24: Input Parameters:
25: + nep - the nonlinear eigensolver context
26: . opt - the command line option for this monitor
27: . name - the monitor type one is seeking
28: . ctx - an optional user context for the monitor, or `NULL`
29: - trackall - whether this monitor tracks all eigenvalues or not
31: Level: developer
33: .seealso: [](ch:nep), `NEPMonitorSet()`, `NEPSetTrackAll()`
34: @*/
35: PetscErrorCode NEPMonitorSetFromOptions(NEP nep,const char opt[],const char name[],void *ctx,PetscBool trackall)
36: {
37: PetscErrorCode (*mfunc)(NEP,PetscInt,PetscInt,PetscScalar*,PetscScalar*,PetscReal*,PetscInt,void*);
38: PetscErrorCode (*cfunc)(PetscViewer,PetscViewerFormat,void*,PetscViewerAndFormat**);
39: PetscErrorCode (*dfunc)(PetscViewerAndFormat**);
40: PetscViewerAndFormat *vf;
41: PetscViewer viewer;
42: PetscViewerFormat format;
43: PetscViewerType vtype;
44: char key[PETSC_MAX_PATH_LEN];
45: PetscBool flg;
47: PetscFunctionBegin;
48: PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)nep),((PetscObject)nep)->options,((PetscObject)nep)->prefix,opt,&viewer,&format,&flg));
49: if (!flg) PetscFunctionReturn(PETSC_SUCCESS);
51: PetscCall(PetscViewerGetType(viewer,&vtype));
52: PetscCall(SlepcMonitorMakeKey_Internal(name,vtype,format,key));
53: PetscCall(PetscFunctionListFind(NEPMonitorList,key,&mfunc));
54: PetscCheck(mfunc,PetscObjectComm((PetscObject)nep),PETSC_ERR_SUP,"Specified viewer and format not supported");
55: PetscCall(PetscFunctionListFind(NEPMonitorCreateList,key,&cfunc));
56: PetscCall(PetscFunctionListFind(NEPMonitorDestroyList,key,&dfunc));
57: if (!cfunc) cfunc = PetscViewerAndFormatCreate_Internal;
58: if (!dfunc) dfunc = PetscViewerAndFormatDestroy;
60: PetscCall((*cfunc)(viewer,format,ctx,&vf));
61: PetscCall(PetscViewerDestroy(&viewer));
62: PetscCall(NEPMonitorSet(nep,mfunc,vf,(PetscCtxDestroyFn*)dfunc));
63: if (trackall) PetscCall(NEPSetTrackAll(nep,PETSC_TRUE));
64: PetscFunctionReturn(PETSC_SUCCESS);
65: }
67: /*@
68: NEPSetFromOptions - Sets `NEP` options from the options database.
69: This routine must be called before `NEPSetUp()` if the user is to be
70: allowed to configure the solver.
72: Collective
74: Input Parameter:
75: . nep - the nonlinear eigensolver context
77: Note:
78: To see all options, run your program with the `-help` option.
80: Level: beginner
82: .seealso: [](ch:nep), `NEPSetOptionsPrefix()`
83: @*/
84: PetscErrorCode NEPSetFromOptions(NEP nep)
85: {
86: char type[256];
87: PetscBool set,flg,flg1,flg2,flg3,flg4,flg5,bval;
88: PetscReal r;
89: PetscScalar s;
90: PetscInt i,j,k;
91: NEPRefine refine;
92: NEPRefineScheme scheme;
94: PetscFunctionBegin;
96: PetscCall(NEPRegisterAll());
97: PetscObjectOptionsBegin((PetscObject)nep);
98: PetscCall(PetscOptionsFList("-nep_type","Nonlinear eigensolver method","NEPSetType",NEPList,(char*)(((PetscObject)nep)->type_name?((PetscObject)nep)->type_name:NEPRII),type,sizeof(type),&flg));
99: if (flg) PetscCall(NEPSetType(nep,type));
100: else if (!((PetscObject)nep)->type_name) PetscCall(NEPSetType(nep,NEPRII));
102: PetscCall(PetscOptionsBoolGroupBegin("-nep_general","General nonlinear eigenvalue problem","NEPSetProblemType",&flg));
103: if (flg) PetscCall(NEPSetProblemType(nep,NEP_GENERAL));
104: PetscCall(PetscOptionsBoolGroupEnd("-nep_rational","Rational eigenvalue problem","NEPSetProblemType",&flg));
105: if (flg) PetscCall(NEPSetProblemType(nep,NEP_RATIONAL));
107: refine = nep->refine;
108: PetscCall(PetscOptionsEnum("-nep_refine","Iterative refinement method","NEPSetRefine",NEPRefineTypes,(PetscEnum)refine,(PetscEnum*)&refine,&flg1));
109: i = nep->npart;
110: PetscCall(PetscOptionsInt("-nep_refine_partitions","Number of partitions of the communicator for iterative refinement","NEPSetRefine",nep->npart,&i,&flg2));
111: r = nep->rtol;
112: PetscCall(PetscOptionsReal("-nep_refine_tol","Tolerance for iterative refinement","NEPSetRefine",nep->rtol==(PetscReal)PETSC_DETERMINE?SLEPC_DEFAULT_TOL/1000:nep->rtol,&r,&flg3));
113: j = nep->rits;
114: PetscCall(PetscOptionsInt("-nep_refine_its","Maximum number of iterations for iterative refinement","NEPSetRefine",nep->rits,&j,&flg4));
115: scheme = nep->scheme;
116: PetscCall(PetscOptionsEnum("-nep_refine_scheme","Scheme used for linear systems within iterative refinement","NEPSetRefine",NEPRefineSchemes,(PetscEnum)scheme,(PetscEnum*)&scheme,&flg5));
117: if (flg1 || flg2 || flg3 || flg4 || flg5) PetscCall(NEPSetRefine(nep,refine,i,r,j,scheme));
119: i = nep->max_it;
120: PetscCall(PetscOptionsInt("-nep_max_it","Maximum number of iterations","NEPSetTolerances",nep->max_it,&i,&flg1));
121: r = nep->tol;
122: PetscCall(PetscOptionsReal("-nep_tol","Tolerance","NEPSetTolerances",SlepcDefaultTol(nep->tol),&r,&flg2));
123: if (flg1 || flg2) PetscCall(NEPSetTolerances(nep,r,i));
125: PetscCall(PetscOptionsBoolGroupBegin("-nep_conv_rel","Relative error convergence test","NEPSetConvergenceTest",&flg));
126: if (flg) PetscCall(NEPSetConvergenceTest(nep,NEP_CONV_REL));
127: PetscCall(PetscOptionsBoolGroup("-nep_conv_norm","Convergence test relative to the matrix norms","NEPSetConvergenceTest",&flg));
128: if (flg) PetscCall(NEPSetConvergenceTest(nep,NEP_CONV_NORM));
129: PetscCall(PetscOptionsBoolGroup("-nep_conv_abs","Absolute error convergence test","NEPSetConvergenceTest",&flg));
130: if (flg) PetscCall(NEPSetConvergenceTest(nep,NEP_CONV_ABS));
131: PetscCall(PetscOptionsBoolGroupEnd("-nep_conv_user","User-defined convergence test","NEPSetConvergenceTest",&flg));
132: if (flg) PetscCall(NEPSetConvergenceTest(nep,NEP_CONV_USER));
134: PetscCall(PetscOptionsBoolGroupBegin("-nep_stop_basic","Stop iteration if all eigenvalues converged or max_it reached","NEPSetStoppingTest",&flg));
135: if (flg) PetscCall(NEPSetStoppingTest(nep,NEP_STOP_BASIC));
136: PetscCall(PetscOptionsBoolGroupEnd("-nep_stop_user","User-defined stopping test","NEPSetStoppingTest",&flg));
137: if (flg) PetscCall(NEPSetStoppingTest(nep,NEP_STOP_USER));
139: i = nep->nev;
140: PetscCall(PetscOptionsInt("-nep_nev","Number of eigenvalues to compute","NEPSetDimensions",nep->nev,&i,&flg1));
141: j = nep->ncv;
142: PetscCall(PetscOptionsInt("-nep_ncv","Number of basis vectors","NEPSetDimensions",nep->ncv,&j,&flg2));
143: k = nep->mpd;
144: PetscCall(PetscOptionsInt("-nep_mpd","Maximum dimension of projected problem","NEPSetDimensions",nep->mpd,&k,&flg3));
145: if (flg1 || flg2 || flg3) PetscCall(NEPSetDimensions(nep,i,j,k));
147: PetscCall(PetscOptionsBoolGroupBegin("-nep_largest_magnitude","Compute largest eigenvalues in magnitude","NEPSetWhichEigenpairs",&flg));
148: if (flg) PetscCall(NEPSetWhichEigenpairs(nep,NEP_LARGEST_MAGNITUDE));
149: PetscCall(PetscOptionsBoolGroup("-nep_smallest_magnitude","Compute smallest eigenvalues in magnitude","NEPSetWhichEigenpairs",&flg));
150: if (flg) PetscCall(NEPSetWhichEigenpairs(nep,NEP_SMALLEST_MAGNITUDE));
151: PetscCall(PetscOptionsBoolGroup("-nep_largest_real","Compute eigenvalues with largest real parts","NEPSetWhichEigenpairs",&flg));
152: if (flg) PetscCall(NEPSetWhichEigenpairs(nep,NEP_LARGEST_REAL));
153: PetscCall(PetscOptionsBoolGroup("-nep_smallest_real","Compute eigenvalues with smallest real parts","NEPSetWhichEigenpairs",&flg));
154: if (flg) PetscCall(NEPSetWhichEigenpairs(nep,NEP_SMALLEST_REAL));
155: PetscCall(PetscOptionsBoolGroup("-nep_largest_imaginary","Compute eigenvalues with largest imaginary parts","NEPSetWhichEigenpairs",&flg));
156: if (flg) PetscCall(NEPSetWhichEigenpairs(nep,NEP_LARGEST_IMAGINARY));
157: PetscCall(PetscOptionsBoolGroup("-nep_smallest_imaginary","Compute eigenvalues with smallest imaginary parts","NEPSetWhichEigenpairs",&flg));
158: if (flg) PetscCall(NEPSetWhichEigenpairs(nep,NEP_SMALLEST_IMAGINARY));
159: PetscCall(PetscOptionsBoolGroup("-nep_target_magnitude","Compute eigenvalues closest to target","NEPSetWhichEigenpairs",&flg));
160: if (flg) PetscCall(NEPSetWhichEigenpairs(nep,NEP_TARGET_MAGNITUDE));
161: PetscCall(PetscOptionsBoolGroup("-nep_target_real","Compute eigenvalues with real parts closest to target","NEPSetWhichEigenpairs",&flg));
162: if (flg) PetscCall(NEPSetWhichEigenpairs(nep,NEP_TARGET_REAL));
163: PetscCall(PetscOptionsBoolGroup("-nep_target_imaginary","Compute eigenvalues with imaginary parts closest to target","NEPSetWhichEigenpairs",&flg));
164: if (flg) PetscCall(NEPSetWhichEigenpairs(nep,NEP_TARGET_IMAGINARY));
165: PetscCall(PetscOptionsBoolGroupEnd("-nep_all","Compute all eigenvalues in a region","NEPSetWhichEigenpairs",&flg));
166: if (flg) PetscCall(NEPSetWhichEigenpairs(nep,NEP_ALL));
168: PetscCall(PetscOptionsScalar("-nep_target","Value of the target","NEPSetTarget",nep->target,&s,&flg));
169: if (flg) {
170: if (nep->which!=NEP_TARGET_REAL && nep->which!=NEP_TARGET_IMAGINARY) PetscCall(NEPSetWhichEigenpairs(nep,NEP_TARGET_MAGNITUDE));
171: PetscCall(NEPSetTarget(nep,s));
172: }
174: PetscCall(PetscOptionsBool("-nep_two_sided","Use two-sided variant (to compute left eigenvectors)","NEPSetTwoSided",nep->twosided,&bval,&flg));
175: if (flg) PetscCall(NEPSetTwoSided(nep,bval));
177: /* -----------------------------------------------------------------------*/
178: /*
179: Cancels all monitors hardwired into code before call to NEPSetFromOptions()
180: */
181: PetscCall(PetscOptionsBool("-nep_monitor_cancel","Remove any hardwired monitor routines","NEPMonitorCancel",PETSC_FALSE,&flg,&set));
182: if (set && flg) PetscCall(NEPMonitorCancel(nep));
183: PetscCall(NEPMonitorSetFromOptions(nep,"-nep_monitor","first_approximation",NULL,PETSC_FALSE));
184: PetscCall(NEPMonitorSetFromOptions(nep,"-nep_monitor_all","all_approximations",NULL,PETSC_TRUE));
185: PetscCall(NEPMonitorSetFromOptions(nep,"-nep_monitor_conv","convergence_history",NULL,PETSC_FALSE));
187: /* -----------------------------------------------------------------------*/
188: PetscCall(PetscOptionsName("-nep_view","Print detailed information on solver used","NEPView",&set));
189: PetscCall(PetscOptionsName("-nep_view_vectors","View computed eigenvectors","NEPVectorsView",&set));
190: PetscCall(PetscOptionsName("-nep_view_values","View computed eigenvalues","NEPValuesView",&set));
191: PetscCall(PetscOptionsName("-nep_converged_reason","Print reason for convergence, and number of iterations","NEPConvergedReasonView",&set));
192: PetscCall(PetscOptionsName("-nep_error_absolute","Print absolute errors of each eigenpair","NEPErrorView",&set));
193: PetscCall(PetscOptionsName("-nep_error_relative","Print relative errors of each eigenpair","NEPErrorView",&set));
195: PetscTryTypeMethod(nep,setfromoptions,PetscOptionsObject);
196: PetscCall(PetscObjectProcessOptionsHandlers((PetscObject)nep,PetscOptionsObject));
197: PetscOptionsEnd();
199: if (!nep->V) PetscCall(NEPGetBV(nep,&nep->V));
200: PetscCall(BVSetFromOptions(nep->V));
201: if (!nep->rg) PetscCall(NEPGetRG(nep,&nep->rg));
202: PetscCall(RGSetFromOptions(nep->rg));
203: if (nep->useds) {
204: if (!nep->ds) PetscCall(NEPGetDS(nep,&nep->ds));
205: PetscCall(NEPSetDSType(nep));
206: PetscCall(DSSetFromOptions(nep->ds));
207: }
208: if (!nep->refineksp) PetscCall(NEPRefineGetKSP(nep,&nep->refineksp));
209: PetscCall(KSPSetFromOptions(nep->refineksp));
210: if (nep->fui==NEP_USER_INTERFACE_SPLIT) for (i=0;i<nep->nt;i++) PetscCall(FNSetFromOptions(nep->f[i]));
211: PetscFunctionReturn(PETSC_SUCCESS);
212: }
214: /*@
215: NEPGetTolerances - Gets the tolerance and maximum iteration count used
216: by the `NEP` convergence tests.
218: Not Collective
220: Input Parameter:
221: . nep - the nonlinear eigensolver context
223: Output Parameters:
224: + tol - the convergence tolerance
225: - maxits - maximum number of iterations
227: Notes:
228: The user can specify `NULL` for any parameter that is not needed.
230: Level: intermediate
232: .seealso: [](ch:nep), `NEPSetTolerances()`
233: @*/
234: PetscErrorCode NEPGetTolerances(NEP nep,PetscReal *tol,PetscInt *maxits)
235: {
236: PetscFunctionBegin;
238: if (tol) *tol = nep->tol;
239: if (maxits) *maxits = nep->max_it;
240: PetscFunctionReturn(PETSC_SUCCESS);
241: }
243: /*@
244: NEPSetTolerances - Sets the tolerance and maximum iteration count used
245: by the `NEP` convergence tests.
247: Logically Collective
249: Input Parameters:
250: + nep - the nonlinear eigensolver context
251: . tol - the convergence tolerance
252: - maxits - maximum number of iterations to use
254: Options Database Keys:
255: + -nep_tol \<tol\> - sets the convergence tolerance
256: - -nep_max_it \<maxits\> - sets the maximum number of iterations allowed
258: Note:
259: Use `PETSC_CURRENT` to retain the current value of any of the parameters.
260: Use `PETSC_DETERMINE` for either argument to assign a default value computed
261: internally (may be different in each solver).
262: For `maxits` use `PETSC_UNLIMITED` to indicate there is no upper bound on this value.
264: Level: intermediate
266: .seealso: [](ch:nep), `NEPGetTolerances()`
267: @*/
268: PetscErrorCode NEPSetTolerances(NEP nep,PetscReal tol,PetscInt maxits)
269: {
270: PetscFunctionBegin;
274: if (tol == (PetscReal)PETSC_DETERMINE) {
275: nep->tol = PETSC_DETERMINE;
276: nep->state = NEP_STATE_INITIAL;
277: } else if (tol != (PetscReal)PETSC_CURRENT) {
278: PetscCheck(tol>0.0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of tol. Must be > 0");
279: nep->tol = tol;
280: }
281: if (maxits == PETSC_DETERMINE) {
282: nep->max_it = PETSC_DETERMINE;
283: nep->state = NEP_STATE_INITIAL;
284: } else if (maxits == PETSC_UNLIMITED) {
285: nep->max_it = PETSC_INT_MAX;
286: } else if (maxits != PETSC_CURRENT) {
287: PetscCheck(maxits>0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of maxits. Must be > 0");
288: nep->max_it = maxits;
289: }
290: PetscFunctionReturn(PETSC_SUCCESS);
291: }
293: /*@
294: NEPGetDimensions - Gets the number of eigenvalues to compute
295: and the dimension of the subspace.
297: Not Collective
299: Input Parameter:
300: . nep - the nonlinear eigensolver context
302: Output Parameters:
303: + nev - number of eigenvalues to compute
304: . ncv - the maximum dimension of the subspace to be used by the solver
305: - mpd - the maximum dimension allowed for the projected problem
307: Note:
308: The user can specify `NULL` for any parameter that is not needed.
310: Level: intermediate
312: .seealso: [](ch:nep), `NEPSetDimensions()`
313: @*/
314: PetscErrorCode NEPGetDimensions(NEP nep,PetscInt *nev,PetscInt *ncv,PetscInt *mpd)
315: {
316: PetscFunctionBegin;
318: if (nev) *nev = nep->nev;
319: if (ncv) *ncv = nep->ncv;
320: if (mpd) *mpd = nep->mpd;
321: PetscFunctionReturn(PETSC_SUCCESS);
322: }
324: /*@
325: NEPSetDimensions - Sets the number of eigenvalues to compute
326: and the dimension of the subspace.
328: Logically Collective
330: Input Parameters:
331: + nep - the nonlinear eigensolver context
332: . nev - number of eigenvalues to compute
333: . ncv - the maximum dimension of the subspace to be used by the solver
334: - mpd - the maximum dimension allowed for the projected problem
336: Options Database Keys:
337: + -nep_nev \<nev\> - sets the number of eigenvalues
338: . -nep_ncv \<ncv\> - sets the dimension of the subspace
339: - -nep_mpd \<mpd\> - sets the maximum projected dimension
341: Notes:
342: Use `PETSC_DETERMINE` for `ncv` and `mpd` to assign a reasonably good value, which is
343: dependent on the solution method. For any of the arguments, use `PETSC_CURRENT`
344: to preserve the current value.
346: The parameters `ncv` and `mpd` are intimately related, so that the user is advised
347: to set one of them at most. Normal usage is\:
349: 1. in cases where `nev` is small, the user sets `ncv` (a reasonable default is `2*nev`).
350: 2. in cases where `nev` is large, the user sets `mpd`.
352: The value of `ncv` should always be between `nev` and `(nev+mpd)`, typically
353: `ncv=nev+mpd`. If `nev` is not too large, `mpd=nev` is a reasonable choice, otherwise
354: a smaller value should be used.
356: Level: intermediate
358: .seealso: [](ch:nep), `NEPGetDimensions()`
359: @*/
360: PetscErrorCode NEPSetDimensions(NEP nep,PetscInt nev,PetscInt ncv,PetscInt mpd)
361: {
362: PetscFunctionBegin;
367: if (nev != PETSC_CURRENT) {
368: PetscCheck(nev>0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of nev. Must be > 0");
369: nep->nev = nev;
370: }
371: if (ncv == PETSC_DETERMINE) {
372: nep->ncv = PETSC_DETERMINE;
373: } else if (ncv != PETSC_CURRENT) {
374: PetscCheck(ncv>0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of ncv. Must be > 0");
375: nep->ncv = ncv;
376: }
377: if (mpd == PETSC_DETERMINE) {
378: nep->mpd = PETSC_DETERMINE;
379: } else if (mpd != PETSC_CURRENT) {
380: PetscCheck(mpd>0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of mpd. Must be > 0");
381: nep->mpd = mpd;
382: }
383: nep->state = NEP_STATE_INITIAL;
384: PetscFunctionReturn(PETSC_SUCCESS);
385: }
387: /*@
388: NEPSetWhichEigenpairs - Specifies which portion of the spectrum is
389: to be sought.
391: Logically Collective
393: Input Parameters:
394: + nep - the nonlinear eigensolver context
395: - which - the portion of the spectrum to be sought, see `NEPWhich` for possible values
397: Options Database Keys:
398: + -nep_largest_magnitude - sets largest eigenvalues in magnitude
399: . -nep_smallest_magnitude - sets smallest eigenvalues in magnitude
400: . -nep_largest_real - sets largest real parts
401: . -nep_smallest_real - sets smallest real parts
402: . -nep_largest_imaginary - sets largest imaginary parts
403: . -nep_smallest_imaginary - sets smallest imaginary parts
404: . -nep_target_magnitude - sets eigenvalues closest to target
405: . -nep_target_real - sets real parts closest to target
406: . -nep_target_imaginary - sets imaginary parts closest to target
407: - -nep_all - sets all eigenvalues in a region
409: Notes:
410: Not all eigensolvers implemented in `NEP` account for all the possible values
411: of `which`. Also, some values make sense only for certain types of
412: problems. If SLEPc is compiled for real numbers `NEP_LARGEST_IMAGINARY`
413: and `NEP_SMALLEST_IMAGINARY` use the absolute value of the imaginary part
414: for eigenvalue selection.
416: The target is a scalar value provided with `NEPSetTarget()`.
418: The criterion `NEP_TARGET_IMAGINARY` is available only in case PETSc and
419: SLEPc have been built with complex scalars.
421: `NEP_ALL` is intended for use in the context of the `NEPCISS` solver for
422: computing all eigenvalues in a region.
424: Level: intermediate
426: .seealso: [](ch:nep), `NEPGetWhichEigenpairs()`, `NEPSetTarget()`, `NEPSetDimensions()`, `NEPSetEigenvalueComparison()`, `NEPWhich`
427: @*/
428: PetscErrorCode NEPSetWhichEigenpairs(NEP nep,NEPWhich which)
429: {
430: PetscFunctionBegin;
433: switch (which) {
434: case NEP_LARGEST_MAGNITUDE:
435: case NEP_SMALLEST_MAGNITUDE:
436: case NEP_LARGEST_REAL:
437: case NEP_SMALLEST_REAL:
438: case NEP_LARGEST_IMAGINARY:
439: case NEP_SMALLEST_IMAGINARY:
440: case NEP_TARGET_MAGNITUDE:
441: case NEP_TARGET_REAL:
442: #if defined(PETSC_USE_COMPLEX)
443: case NEP_TARGET_IMAGINARY:
444: #endif
445: case NEP_ALL:
446: case NEP_WHICH_USER:
447: if (nep->which != which) {
448: nep->state = NEP_STATE_INITIAL;
449: nep->which = which;
450: }
451: break;
452: #if !defined(PETSC_USE_COMPLEX)
453: case NEP_TARGET_IMAGINARY:
454: SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_SUP,"NEP_TARGET_IMAGINARY can be used only with complex scalars");
455: #endif
456: default:
457: SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'which' value");
458: }
459: PetscFunctionReturn(PETSC_SUCCESS);
460: }
462: /*@
463: NEPGetWhichEigenpairs - Returns which portion of the spectrum is to be
464: sought.
466: Not Collective
468: Input Parameter:
469: . nep - the nonlinear eigensolver context
471: Output Parameter:
472: . which - the portion of the spectrum to be sought
474: Level: intermediate
476: .seealso: [](ch:nep), `NEPSetWhichEigenpairs()`, `NEPWhich`
477: @*/
478: PetscErrorCode NEPGetWhichEigenpairs(NEP nep,NEPWhich *which)
479: {
480: PetscFunctionBegin;
482: PetscAssertPointer(which,2);
483: *which = nep->which;
484: PetscFunctionReturn(PETSC_SUCCESS);
485: }
487: /*@C
488: NEPSetEigenvalueComparison - Specifies the eigenvalue comparison function
489: when `NEPSetWhichEigenpairs()` is set to `NEP_WHICH_USER`.
491: Logically Collective
493: Input Parameters:
494: + nep - the nonlinear eigensolver context
495: . comp - a pointer to the comparison function, see `SlepcEigenvalueComparisonFn` for the calling sequence
496: - ctx - a context pointer (the last parameter to the comparison function)
498: Level: advanced
500: .seealso: [](ch:nep), `NEPSetWhichEigenpairs()`, `NEPWhich`
501: @*/
502: PetscErrorCode NEPSetEigenvalueComparison(NEP nep,SlepcEigenvalueComparisonFn *comp,void *ctx)
503: {
504: PetscFunctionBegin;
506: nep->sc->comparison = comp;
507: nep->sc->comparisonctx = ctx;
508: nep->which = NEP_WHICH_USER;
509: PetscFunctionReturn(PETSC_SUCCESS);
510: }
512: /*@
513: NEPSetProblemType - Specifies the type of the nonlinear eigenvalue problem.
515: Logically Collective
517: Input Parameters:
518: + nep - the nonlinear eigensolver context
519: - type - a known type of nonlinear eigenvalue problem
521: Options Database Keys:
522: + -nep_general - general problem with no particular structure
523: - -nep_rational - a rational eigenvalue problem defined in split form with all $f_i$ rational
525: Notes:
526: See `NEPProblemType` for possible problem types.
528: This function is used to provide a hint to the `NEP` solver to exploit certain
529: properties of the nonlinear eigenproblem. This hint may be used or not,
530: depending on the solver. By default, no particular structure is assumed.
532: Level: intermediate
534: .seealso: [](ch:nep), `NEPSetType()`, `NEPGetProblemType()`, `NEPProblemType`
535: @*/
536: PetscErrorCode NEPSetProblemType(NEP nep,NEPProblemType type)
537: {
538: PetscFunctionBegin;
541: PetscCheck(type==NEP_GENERAL || type==NEP_RATIONAL,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_WRONG,"Unknown eigenvalue problem type");
542: if (type != nep->problem_type) {
543: nep->problem_type = type;
544: nep->state = NEP_STATE_INITIAL;
545: }
546: PetscFunctionReturn(PETSC_SUCCESS);
547: }
549: /*@
550: NEPGetProblemType - Gets the problem type from the `NEP` object.
552: Not Collective
554: Input Parameter:
555: . nep - the nonlinear eigensolver context
557: Output Parameter:
558: . type - the problem type
560: Level: intermediate
562: .seealso: [](ch:nep), `NEPSetProblemType()`, `NEPProblemType`
563: @*/
564: PetscErrorCode NEPGetProblemType(NEP nep,NEPProblemType *type)
565: {
566: PetscFunctionBegin;
568: PetscAssertPointer(type,2);
569: *type = nep->problem_type;
570: PetscFunctionReturn(PETSC_SUCCESS);
571: }
573: /*@
574: NEPSetTwoSided - Sets the solver to use a two-sided variant so that left
575: eigenvectors are also computed.
577: Logically Collective
579: Input Parameters:
580: + nep - the nonlinear eigensolver context
581: - twosided - whether the two-sided variant is to be used or not
583: Options Database Key:
584: . -nep_two_sided - toggles the twosided flag
586: Notes:
587: If the user sets `twosided`=`PETSC_TRUE` then the solver uses a variant of
588: the algorithm that computes both right and left eigenvectors. This is
589: usually much more costly. This option is not available in all solvers,
590: see table [](#tab:solversn).
592: When using two-sided solvers, the problem matrices must have both the
593: `MATOP_MULT` and `MATOP_MULT_TRANSPOSE` operations defined.
595: Level: advanced
597: .seealso: [](ch:nep), `NEPGetTwoSided()`, `NEPGetLeftEigenvector()`
598: @*/
599: PetscErrorCode NEPSetTwoSided(NEP nep,PetscBool twosided)
600: {
601: PetscFunctionBegin;
604: if (twosided!=nep->twosided) {
605: nep->twosided = twosided;
606: nep->state = NEP_STATE_INITIAL;
607: }
608: PetscFunctionReturn(PETSC_SUCCESS);
609: }
611: /*@
612: NEPGetTwoSided - Returns the flag indicating whether a two-sided variant
613: of the algorithm is being used or not.
615: Not Collective
617: Input Parameter:
618: . nep - the nonlinear eigensolver context
620: Output Parameter:
621: . twosided - the returned flag
623: Level: advanced
625: .seealso: [](ch:nep), `NEPSetTwoSided()`
626: @*/
627: PetscErrorCode NEPGetTwoSided(NEP nep,PetscBool *twosided)
628: {
629: PetscFunctionBegin;
631: PetscAssertPointer(twosided,2);
632: *twosided = nep->twosided;
633: PetscFunctionReturn(PETSC_SUCCESS);
634: }
636: /*@C
637: NEPSetConvergenceTestFunction - Sets a function to compute the error estimate
638: used in the convergence test.
640: Logically Collective
642: Input Parameters:
643: + nep - the nonlinear eigensolver context
644: . conv - convergence test function, see `NEPConvergenceTestFn` for the calling sequence
645: . ctx - context for private data for the convergence routine (may be `NULL`)
646: - destroy - a routine for destroying the context (may be `NULL`), see `PetscCtxDestroyFn`
647: for the calling sequence
649: Notes:
650: When this is called with a user-defined function, then the convergence
651: criterion is set to `NEP_CONV_USER`, see `NEPSetConvergenceTest()`.
653: If the error estimate returned by the convergence test function is less than
654: the tolerance, then the eigenvalue is accepted as converged.
656: Level: advanced
658: .seealso: [](ch:nep), `NEPSetConvergenceTest()`, `NEPSetTolerances()`
659: @*/
660: PetscErrorCode NEPSetConvergenceTestFunction(NEP nep,NEPConvergenceTestFn *conv,void *ctx,PetscCtxDestroyFn *destroy)
661: {
662: PetscFunctionBegin;
664: if (nep->convergeddestroy) PetscCall((*nep->convergeddestroy)(&nep->convergedctx));
665: nep->convergeduser = conv;
666: nep->convergeddestroy = destroy;
667: nep->convergedctx = ctx;
668: if (conv == NEPConvergedRelative) nep->conv = NEP_CONV_REL;
669: else if (conv == NEPConvergedNorm) nep->conv = NEP_CONV_NORM;
670: else if (conv == NEPConvergedAbsolute) nep->conv = NEP_CONV_ABS;
671: else {
672: nep->conv = NEP_CONV_USER;
673: nep->converged = nep->convergeduser;
674: }
675: PetscFunctionReturn(PETSC_SUCCESS);
676: }
678: /*@
679: NEPSetConvergenceTest - Specifies how to compute the error estimate
680: used in the convergence test.
682: Logically Collective
684: Input Parameters:
685: + nep - the nonlinear eigensolver context
686: - conv - the type of convergence test, see `NEPConv` for possible values
688: Options Database Keys:
689: + -nep_conv_abs - sets the absolute convergence test
690: . -nep_conv_rel - sets the convergence test relative to the eigenvalue
691: . -nep_conv_norm - sets the convergence test relative to the matrix norms
692: - -nep_conv_user - selects the user-defined convergence test
694: Level: intermediate
696: .seealso: [](ch:nep), `NEPGetConvergenceTest()`, `NEPSetConvergenceTestFunction()`, `NEPSetStoppingTest()`, `NEPConv`
697: @*/
698: PetscErrorCode NEPSetConvergenceTest(NEP nep,NEPConv conv)
699: {
700: PetscFunctionBegin;
703: switch (conv) {
704: case NEP_CONV_ABS: nep->converged = NEPConvergedAbsolute; break;
705: case NEP_CONV_REL: nep->converged = NEPConvergedRelative; break;
706: case NEP_CONV_NORM: nep->converged = NEPConvergedNorm; break;
707: case NEP_CONV_USER:
708: PetscCheck(nep->convergeduser,PetscObjectComm((PetscObject)nep),PETSC_ERR_ORDER,"Must call NEPSetConvergenceTestFunction() first");
709: nep->converged = nep->convergeduser;
710: break;
711: default:
712: SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'conv' value");
713: }
714: nep->conv = conv;
715: PetscFunctionReturn(PETSC_SUCCESS);
716: }
718: /*@
719: NEPGetConvergenceTest - Gets the method used to compute the error estimate
720: used in the convergence test.
722: Not Collective
724: Input Parameter:
725: . nep - the nonlinear eigensolver context
727: Output Parameter:
728: . conv - the type of convergence test
730: Level: intermediate
732: .seealso: [](ch:nep), `NEPSetConvergenceTest()`, `NEPConv`
733: @*/
734: PetscErrorCode NEPGetConvergenceTest(NEP nep,NEPConv *conv)
735: {
736: PetscFunctionBegin;
738: PetscAssertPointer(conv,2);
739: *conv = nep->conv;
740: PetscFunctionReturn(PETSC_SUCCESS);
741: }
743: /*@C
744: NEPSetStoppingTestFunction - Sets a function to decide when to stop the outer
745: iteration of the eigensolver.
747: Logically Collective
749: Input Parameters:
750: + nep - the nonlinear eigensolver context
751: . stop - the stopping test function, see `NEPStoppingTestFn` for the calling sequence
752: . ctx - context for private data for the stopping routine (may be `NULL`)
753: - destroy - a routine for destroying the context (may be `NULL`), see `PetscCtxDestroyFn`
754: for the calling sequence
756: Note:
757: When implementing a function for this, normal usage is to first call the
758: default routine `NEPStoppingBasic()` and then set `reason` to `NEP_CONVERGED_USER`
759: if some user-defined conditions have been met. To let the eigensolver continue
760: iterating, the result must be left as `NEP_CONVERGED_ITERATING`.
762: Level: advanced
764: .seealso: [](ch:nep), `NEPSetStoppingTest()`, `NEPStoppingBasic()`
765: @*/
766: PetscErrorCode NEPSetStoppingTestFunction(NEP nep,NEPStoppingTestFn *stop,void *ctx,PetscCtxDestroyFn *destroy)
767: {
768: PetscFunctionBegin;
770: if (nep->stoppingdestroy) PetscCall((*nep->stoppingdestroy)(&nep->stoppingctx));
771: nep->stoppinguser = stop;
772: nep->stoppingdestroy = destroy;
773: nep->stoppingctx = ctx;
774: if (stop == NEPStoppingBasic) nep->stop = NEP_STOP_BASIC;
775: else {
776: nep->stop = NEP_STOP_USER;
777: nep->stopping = nep->stoppinguser;
778: }
779: PetscFunctionReturn(PETSC_SUCCESS);
780: }
782: /*@
783: NEPSetStoppingTest - Specifies how to decide the termination of the outer
784: loop of the eigensolver.
786: Logically Collective
788: Input Parameters:
789: + nep - the nonlinear eigensolver context
790: - stop - the type of stopping test, see `NEPStop`
792: Options Database Keys:
793: + -nep_stop_basic - sets the default stopping test
794: - -nep_stop_user - selects the user-defined stopping test
796: Level: advanced
798: .seealso: [](ch:nep), `NEPGetStoppingTest()`, `NEPSetStoppingTestFunction()`, `NEPSetConvergenceTest()`, `NEPStop`
799: @*/
800: PetscErrorCode NEPSetStoppingTest(NEP nep,NEPStop stop)
801: {
802: PetscFunctionBegin;
805: switch (stop) {
806: case NEP_STOP_BASIC: nep->stopping = NEPStoppingBasic; break;
807: case NEP_STOP_USER:
808: PetscCheck(nep->stoppinguser,PetscObjectComm((PetscObject)nep),PETSC_ERR_ORDER,"Must call NEPSetStoppingTestFunction() first");
809: nep->stopping = nep->stoppinguser;
810: break;
811: default:
812: SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'stop' value");
813: }
814: nep->stop = stop;
815: PetscFunctionReturn(PETSC_SUCCESS);
816: }
818: /*@
819: NEPGetStoppingTest - Gets the method used to decide the termination of the outer
820: loop of the eigensolver.
822: Not Collective
824: Input Parameter:
825: . nep - the nonlinear eigensolver context
827: Output Parameter:
828: . stop - the type of stopping test
830: Level: advanced
832: .seealso: [](ch:nep), `NEPSetStoppingTest()`, `NEPStop`
833: @*/
834: PetscErrorCode NEPGetStoppingTest(NEP nep,NEPStop *stop)
835: {
836: PetscFunctionBegin;
838: PetscAssertPointer(stop,2);
839: *stop = nep->stop;
840: PetscFunctionReturn(PETSC_SUCCESS);
841: }
843: /*@
844: NEPSetTrackAll - Specifies if the solver must compute the residual of all
845: approximate eigenpairs or not.
847: Logically Collective
849: Input Parameters:
850: + nep - the nonlinear eigensolver context
851: - trackall - whether compute all residuals or not
853: Notes:
854: If the user sets `trackall`=`PETSC_TRUE` then the solver explicitly computes
855: the residual for each eigenpair approximation. Computing the residual is
856: usually an expensive operation and solvers commonly compute the associated
857: residual to the first unconverged eigenpair.
859: The option `-nep_monitor_all` automatically activates this option.
861: Level: developer
863: .seealso: [](ch:nep), `NEPGetTrackAll()`
864: @*/
865: PetscErrorCode NEPSetTrackAll(NEP nep,PetscBool trackall)
866: {
867: PetscFunctionBegin;
870: nep->trackall = trackall;
871: PetscFunctionReturn(PETSC_SUCCESS);
872: }
874: /*@
875: NEPGetTrackAll - Returns the flag indicating whether all residual norms must
876: be computed or not.
878: Not Collective
880: Input Parameter:
881: . nep - the nonlinear eigensolver context
883: Output Parameter:
884: . trackall - the returned flag
886: Level: developer
888: .seealso: [](ch:nep), `NEPSetTrackAll()`
889: @*/
890: PetscErrorCode NEPGetTrackAll(NEP nep,PetscBool *trackall)
891: {
892: PetscFunctionBegin;
894: PetscAssertPointer(trackall,2);
895: *trackall = nep->trackall;
896: PetscFunctionReturn(PETSC_SUCCESS);
897: }
899: /*@
900: NEPSetRefine - Specifies the refinement type (and options) to be used
901: after the solve.
903: Logically Collective
905: Input Parameters:
906: + nep - the nonlinear eigensolver context
907: . refine - refinement type, see `NEPRefine` for possible values
908: . npart - number of partitions of the communicator
909: . tol - the convergence tolerance
910: . its - maximum number of refinement iterations
911: - scheme - which scheme to be used for solving the involved linear systems, see `NEPRefineScheme`
912: for possible values
914: Options Database Keys:
915: + -nep_refine \<refine\> - set the refinement type, one of `none`,`simple`,`multiple`
916: . -nep_refine_partitions \<npart\> - set the number of partitions
917: . -nep_refine_tol \<tol\> - set the tolerance
918: . -nep_refine_its \<its\> - set the number of iterations
919: - -nep_refine_scheme \<scheme\> - set the scheme for the linear solves, `schur`,`mbe`, or `explicit`
921: Notes:
922: This function configures the parameters of Newton iterative refinement,
923: see section [](#sec:refine) for a discussion of the different strategies
924: in the context of polynomial eigenproblems.
926: By default, iterative refinement is disabled, since it may be very
927: costly. There are two possible refinement strategies, simple and multiple.
928: The simple approach performs iterative refinement on each of the
929: converged eigenpairs individually, whereas the multiple strategy works
930: with the invariant pair as a whole, refining all eigenpairs simultaneously.
931: The latter may be required for the case of multiple eigenvalues.
933: In some cases, especially when using direct solvers within the
934: iterative refinement method, it may be helpful for improved scalability
935: to split the communicator in several partitions. The `npart` parameter
936: indicates how many partitions to use (defaults to 1).
938: The `tol` and `its` parameters specify the stopping criterion. In the simple
939: method, refinement continues until the residual of each eigenpair is
940: below the tolerance (`tol` defaults to the `NEP` tolerance, but may be set to a
941: different value). In contrast, the multiple method simply performs its
942: refinement iterations (just one by default).
944: The `scheme` argument is used to change the way in which linear systems are
945: solved. Possible choices are explicit, mixed block elimination (MBE),
946: and Schur complement.
948: Use `PETSC_CURRENT` to retain the current value of `npart`, `tol` or `its`. Use
949: `PETSC_DETERMINE` to assign a default value.
951: Level: intermediate
953: .seealso: [](ch:nep), [](#sec:refine), `NEPGetRefine()`
954: @*/
955: PetscErrorCode NEPSetRefine(NEP nep,NEPRefine refine,PetscInt npart,PetscReal tol,PetscInt its,NEPRefineScheme scheme)
956: {
957: PetscMPIInt size;
959: PetscFunctionBegin;
966: nep->refine = refine;
967: if (refine) { /* process parameters only if not REFINE_NONE */
968: if (npart!=nep->npart) {
969: PetscCall(PetscSubcommDestroy(&nep->refinesubc));
970: PetscCall(KSPDestroy(&nep->refineksp));
971: }
972: if (npart == PETSC_DETERMINE) {
973: nep->npart = 1;
974: } else if (npart != PETSC_CURRENT) {
975: PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)nep),&size));
976: PetscCheck(npart>0 && npart<=size,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of npart");
977: nep->npart = npart;
978: }
979: if (tol == (PetscReal)PETSC_DETERMINE) {
980: nep->rtol = PETSC_DETERMINE;
981: } else if (tol != (PetscReal)PETSC_CURRENT) {
982: PetscCheck(tol>0.0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of tol. Must be > 0");
983: nep->rtol = tol;
984: }
985: if (its==PETSC_DETERMINE) {
986: nep->rits = PETSC_DETERMINE;
987: } else if (its != PETSC_CURRENT) {
988: PetscCheck(its>=0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of its. Must be >= 0");
989: nep->rits = its;
990: }
991: nep->scheme = scheme;
992: }
993: nep->state = NEP_STATE_INITIAL;
994: PetscFunctionReturn(PETSC_SUCCESS);
995: }
997: /*@
998: NEPGetRefine - Gets the refinement strategy used by the `NEP` object, and the
999: associated parameters.
1001: Not Collective
1003: Input Parameter:
1004: . nep - the nonlinear eigensolver context
1006: Output Parameters:
1007: + refine - refinement type
1008: . npart - number of partitions of the communicator
1009: . tol - the convergence tolerance
1010: . its - maximum number of refinement iterations
1011: - scheme - the scheme used for solving linear systems
1013: Level: intermediate
1015: Note:
1016: The user can specify `NULL` for any parameter that is not needed.
1018: .seealso: [](ch:nep), `NEPSetRefine()`
1019: @*/
1020: PetscErrorCode NEPGetRefine(NEP nep,NEPRefine *refine,PetscInt *npart,PetscReal *tol,PetscInt *its,NEPRefineScheme *scheme)
1021: {
1022: PetscFunctionBegin;
1024: if (refine) *refine = nep->refine;
1025: if (npart) *npart = nep->npart;
1026: if (tol) *tol = nep->rtol;
1027: if (its) *its = nep->rits;
1028: if (scheme) *scheme = nep->scheme;
1029: PetscFunctionReturn(PETSC_SUCCESS);
1030: }
1032: /*@
1033: NEPSetOptionsPrefix - Sets the prefix used for searching for all
1034: `NEP` options in the database.
1036: Logically Collective
1038: Input Parameters:
1039: + nep - the nonlinear eigensolver context
1040: - prefix - the prefix string to prepend to all `NEP` option requests
1042: Notes:
1043: A hyphen (-) must NOT be given at the beginning of the prefix name.
1044: The first character of all runtime options is AUTOMATICALLY the
1045: hyphen.
1047: For example, to distinguish between the runtime options for two
1048: different `NEP` contexts, one could call
1049: .vb
1050: NEPSetOptionsPrefix(nep1,"neig1_")
1051: NEPSetOptionsPrefix(nep2,"neig2_")
1052: .ve
1054: Level: advanced
1056: .seealso: [](ch:nep), `NEPAppendOptionsPrefix()`, `NEPGetOptionsPrefix()`
1057: @*/
1058: PetscErrorCode NEPSetOptionsPrefix(NEP nep,const char prefix[])
1059: {
1060: PetscFunctionBegin;
1062: if (!nep->V) PetscCall(NEPGetBV(nep,&nep->V));
1063: PetscCall(BVSetOptionsPrefix(nep->V,prefix));
1064: if (!nep->ds) PetscCall(NEPGetDS(nep,&nep->ds));
1065: PetscCall(DSSetOptionsPrefix(nep->ds,prefix));
1066: if (!nep->rg) PetscCall(NEPGetRG(nep,&nep->rg));
1067: PetscCall(RGSetOptionsPrefix(nep->rg,prefix));
1068: PetscCall(PetscObjectSetOptionsPrefix((PetscObject)nep,prefix));
1069: PetscFunctionReturn(PETSC_SUCCESS);
1070: }
1072: /*@
1073: NEPAppendOptionsPrefix - Appends to the prefix used for searching for all
1074: `NEP` options in the database.
1076: Logically Collective
1078: Input Parameters:
1079: + nep - the nonlinear eigensolver context
1080: - prefix - the prefix string to prepend to all `NEP` option requests
1082: Notes:
1083: A hyphen (-) must NOT be given at the beginning of the prefix name.
1084: The first character of all runtime options is AUTOMATICALLY the hyphen.
1086: Level: advanced
1088: .seealso: [](ch:nep), `NEPSetOptionsPrefix()`, `NEPGetOptionsPrefix()`
1089: @*/
1090: PetscErrorCode NEPAppendOptionsPrefix(NEP nep,const char prefix[])
1091: {
1092: PetscFunctionBegin;
1094: if (!nep->V) PetscCall(NEPGetBV(nep,&nep->V));
1095: PetscCall(BVAppendOptionsPrefix(nep->V,prefix));
1096: if (!nep->ds) PetscCall(NEPGetDS(nep,&nep->ds));
1097: PetscCall(DSAppendOptionsPrefix(nep->ds,prefix));
1098: if (!nep->rg) PetscCall(NEPGetRG(nep,&nep->rg));
1099: PetscCall(RGAppendOptionsPrefix(nep->rg,prefix));
1100: PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)nep,prefix));
1101: PetscFunctionReturn(PETSC_SUCCESS);
1102: }
1104: /*@
1105: NEPGetOptionsPrefix - Gets the prefix used for searching for all
1106: `NEP` options in the database.
1108: Not Collective
1110: Input Parameter:
1111: . nep - the nonlinear eigensolver context
1113: Output Parameter:
1114: . prefix - pointer to the prefix string used is returned
1116: Level: advanced
1118: .seealso: [](ch:nep), `NEPSetOptionsPrefix()`, `NEPAppendOptionsPrefix()`
1119: @*/
1120: PetscErrorCode NEPGetOptionsPrefix(NEP nep,const char *prefix[])
1121: {
1122: PetscFunctionBegin;
1124: PetscAssertPointer(prefix,2);
1125: PetscCall(PetscObjectGetOptionsPrefix((PetscObject)nep,prefix));
1126: PetscFunctionReturn(PETSC_SUCCESS);
1127: }