Date: 2022-08-09T09:05:53+00:00

Actual source code: nepopts.c
slepc-3.17.2 2022-08-09
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      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 on nep

     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: 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:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)nep),((PetscObject)nep)->options,((PetscObject)nep)->prefix,opt,&viewer,&format,&flg);
     48:   if (!flg) PetscFunctionReturn(0);

     50:   PetscViewerGetType(viewer,&vtype);
     51:   SlepcMonitorMakeKey_Internal(name,vtype,format,key);
     52:   PetscFunctionListFind(NEPMonitorList,key,&mfunc);
     54:   PetscFunctionListFind(NEPMonitorCreateList,key,&cfunc);
     55:   PetscFunctionListFind(NEPMonitorDestroyList,key,&dfunc);
     56:   if (!cfunc) cfunc = PetscViewerAndFormatCreate_Internal;
     57:   if (!dfunc) dfunc = PetscViewerAndFormatDestroy;

     59:   (*cfunc)(viewer,format,ctx,&vf);
     60:   PetscObjectDereference((PetscObject)viewer);
     61:   NEPMonitorSet(nep,mfunc,vf,(PetscErrorCode(*)(void **))dfunc);
     62:   if (trackall) NEPSetTrackAll(nep,PETSC_TRUE);
     63:   PetscFunctionReturn(0);
     64: }

     66: /*@
     67:    NEPSetFromOptions - Sets NEP options from the options database.
     68:    This routine must be called before NEPSetUp() if the user is to be
     69:    allowed to set the solver type.

     71:    Collective on nep

     73:    Input Parameters:
     74: .  nep - the nonlinear eigensolver context

     76:    Notes:
     77:    To see all options, run your program with the -help option.

     79:    Level: beginner

     81: .seealso: NEPSetOptionsPrefix()
     82: @*/
     83: PetscErrorCode NEPSetFromOptions(NEP nep)
     84: {
     85:   PetscErrorCode  ierr;
     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;

     95:   NEPRegisterAll();
     96:   ierr = PetscObjectOptionsBegin((PetscObject)nep);
     97:     PetscOptionsFList("-nep_type","Nonlinear eigensolver method","NEPSetType",NEPList,(char*)(((PetscObject)nep)->type_name?((PetscObject)nep)->type_name:NEPRII),type,sizeof(type),&flg);
     98:     if (flg) NEPSetType(nep,type);
     99:     else if (!((PetscObject)nep)->type_name) NEPSetType(nep,NEPRII);

    101:     PetscOptionsBoolGroupBegin("-nep_general","General nonlinear eigenvalue problem","NEPSetProblemType",&flg);
    102:     if (flg) NEPSetProblemType(nep,NEP_GENERAL);
    103:     PetscOptionsBoolGroupEnd("-nep_rational","Rational eigenvalue problem","NEPSetProblemType",&flg);
    104:     if (flg) NEPSetProblemType(nep,NEP_RATIONAL);

    106:     refine = nep->refine;
    107:     PetscOptionsEnum("-nep_refine","Iterative refinement method","NEPSetRefine",NEPRefineTypes,(PetscEnum)refine,(PetscEnum*)&refine,&flg1);
    108:     i = nep->npart;
    109:     PetscOptionsInt("-nep_refine_partitions","Number of partitions of the communicator for iterative refinement","NEPSetRefine",nep->npart,&i,&flg2);
    110:     r = nep->rtol;
    111:     PetscOptionsReal("-nep_refine_tol","Tolerance for iterative refinement","NEPSetRefine",nep->rtol==PETSC_DEFAULT?SLEPC_DEFAULT_TOL/1000:nep->rtol,&r,&flg3);
    112:     j = nep->rits;
    113:     PetscOptionsInt("-nep_refine_its","Maximum number of iterations for iterative refinement","NEPSetRefine",nep->rits,&j,&flg4);
    114:     scheme = nep->scheme;
    115:     PetscOptionsEnum("-nep_refine_scheme","Scheme used for linear systems within iterative refinement","NEPSetRefine",NEPRefineSchemes,(PetscEnum)scheme,(PetscEnum*)&scheme,&flg5);
    116:     if (flg1 || flg2 || flg3 || flg4 || flg5) NEPSetRefine(nep,refine,i,r,j,scheme);

    118:     i = nep->max_it;
    119:     PetscOptionsInt("-nep_max_it","Maximum number of iterations","NEPSetTolerances",nep->max_it,&i,&flg1);
    120:     r = nep->tol;
    121:     PetscOptionsReal("-nep_tol","Tolerance","NEPSetTolerances",SlepcDefaultTol(nep->tol),&r,&flg2);
    122:     if (flg1 || flg2) NEPSetTolerances(nep,r,i);

    124:     PetscOptionsBoolGroupBegin("-nep_conv_rel","Relative error convergence test","NEPSetConvergenceTest",&flg);
    125:     if (flg) NEPSetConvergenceTest(nep,NEP_CONV_REL);
    126:     PetscOptionsBoolGroup("-nep_conv_norm","Convergence test relative to the matrix norms","NEPSetConvergenceTest",&flg);
    127:     if (flg) NEPSetConvergenceTest(nep,NEP_CONV_NORM);
    128:     PetscOptionsBoolGroup("-nep_conv_abs","Absolute error convergence test","NEPSetConvergenceTest",&flg);
    129:     if (flg) NEPSetConvergenceTest(nep,NEP_CONV_ABS);
    130:     PetscOptionsBoolGroupEnd("-nep_conv_user","User-defined convergence test","NEPSetConvergenceTest",&flg);
    131:     if (flg) NEPSetConvergenceTest(nep,NEP_CONV_USER);

    133:     PetscOptionsBoolGroupBegin("-nep_stop_basic","Stop iteration if all eigenvalues converged or max_it reached","NEPSetStoppingTest",&flg);
    134:     if (flg) NEPSetStoppingTest(nep,NEP_STOP_BASIC);
    135:     PetscOptionsBoolGroupEnd("-nep_stop_user","User-defined stopping test","NEPSetStoppingTest",&flg);
    136:     if (flg) NEPSetStoppingTest(nep,NEP_STOP_USER);

    138:     i = nep->nev;
    139:     PetscOptionsInt("-nep_nev","Number of eigenvalues to compute","NEPSetDimensions",nep->nev,&i,&flg1);
    140:     j = nep->ncv;
    141:     PetscOptionsInt("-nep_ncv","Number of basis vectors","NEPSetDimensions",nep->ncv,&j,&flg2);
    142:     k = nep->mpd;
    143:     PetscOptionsInt("-nep_mpd","Maximum dimension of projected problem","NEPSetDimensions",nep->mpd,&k,&flg3);
    144:     if (flg1 || flg2 || flg3) NEPSetDimensions(nep,i,j,k);

    146:     PetscOptionsBoolGroupBegin("-nep_largest_magnitude","Compute largest eigenvalues in magnitude","NEPSetWhichEigenpairs",&flg);
    147:     if (flg) NEPSetWhichEigenpairs(nep,NEP_LARGEST_MAGNITUDE);
    148:     PetscOptionsBoolGroup("-nep_smallest_magnitude","Compute smallest eigenvalues in magnitude","NEPSetWhichEigenpairs",&flg);
    149:     if (flg) NEPSetWhichEigenpairs(nep,NEP_SMALLEST_MAGNITUDE);
    150:     PetscOptionsBoolGroup("-nep_largest_real","Compute eigenvalues with largest real parts","NEPSetWhichEigenpairs",&flg);
    151:     if (flg) NEPSetWhichEigenpairs(nep,NEP_LARGEST_REAL);
    152:     PetscOptionsBoolGroup("-nep_smallest_real","Compute eigenvalues with smallest real parts","NEPSetWhichEigenpairs",&flg);
    153:     if (flg) NEPSetWhichEigenpairs(nep,NEP_SMALLEST_REAL);
    154:     PetscOptionsBoolGroup("-nep_largest_imaginary","Compute eigenvalues with largest imaginary parts","NEPSetWhichEigenpairs",&flg);
    155:     if (flg) NEPSetWhichEigenpairs(nep,NEP_LARGEST_IMAGINARY);
    156:     PetscOptionsBoolGroup("-nep_smallest_imaginary","Compute eigenvalues with smallest imaginary parts","NEPSetWhichEigenpairs",&flg);
    157:     if (flg) NEPSetWhichEigenpairs(nep,NEP_SMALLEST_IMAGINARY);
    158:     PetscOptionsBoolGroup("-nep_target_magnitude","Compute eigenvalues closest to target","NEPSetWhichEigenpairs",&flg);
    159:     if (flg) NEPSetWhichEigenpairs(nep,NEP_TARGET_MAGNITUDE);
    160:     PetscOptionsBoolGroup("-nep_target_real","Compute eigenvalues with real parts closest to target","NEPSetWhichEigenpairs",&flg);
    161:     if (flg) NEPSetWhichEigenpairs(nep,NEP_TARGET_REAL);
    162:     PetscOptionsBoolGroup("-nep_target_imaginary","Compute eigenvalues with imaginary parts closest to target","NEPSetWhichEigenpairs",&flg);
    163:     if (flg) NEPSetWhichEigenpairs(nep,NEP_TARGET_IMAGINARY);
    164:     PetscOptionsBoolGroupEnd("-nep_all","Compute all eigenvalues in a region","NEPSetWhichEigenpairs",&flg);
    165:     if (flg) NEPSetWhichEigenpairs(nep,NEP_ALL);

    167:     PetscOptionsScalar("-nep_target","Value of the target","NEPSetTarget",nep->target,&s,&flg);
    168:     if (flg) {
    169:       if (nep->which!=NEP_TARGET_REAL && nep->which!=NEP_TARGET_IMAGINARY) NEPSetWhichEigenpairs(nep,NEP_TARGET_MAGNITUDE);
    170:       NEPSetTarget(nep,s);
    171:     }

    173:     PetscOptionsBool("-nep_two_sided","Use two-sided variant (to compute left eigenvectors)","NEPSetTwoSided",nep->twosided,&bval,&flg);
    174:     if (flg) NEPSetTwoSided(nep,bval);

    176:     /* -----------------------------------------------------------------------*/
    177:     /*
    178:       Cancels all monitors hardwired into code before call to NEPSetFromOptions()
    179:     */
    180:     PetscOptionsBool("-nep_monitor_cancel","Remove any hardwired monitor routines","NEPMonitorCancel",PETSC_FALSE,&flg,&set);
    181:     if (set && flg) NEPMonitorCancel(nep);
    182:     NEPMonitorSetFromOptions(nep,"-nep_monitor","first_approximation",NULL,PETSC_FALSE);
    183:     NEPMonitorSetFromOptions(nep,"-nep_monitor_all","all_approximations",NULL,PETSC_TRUE);
    184:     NEPMonitorSetFromOptions(nep,"-nep_monitor_conv","convergence_history",NULL,PETSC_FALSE);

    186:     /* -----------------------------------------------------------------------*/
    187:     PetscOptionsName("-nep_view","Print detailed information on solver used","NEPView",NULL);
    188:     PetscOptionsName("-nep_view_vectors","View computed eigenvectors","NEPVectorsView",NULL);
    189:     PetscOptionsName("-nep_view_values","View computed eigenvalues","NEPValuesView",NULL);
    190:     PetscOptionsName("-nep_converged_reason","Print reason for convergence, and number of iterations","NEPConvergedReasonView",NULL);
    191:     PetscOptionsName("-nep_error_absolute","Print absolute errors of each eigenpair","NEPErrorView",NULL);
    192:     PetscOptionsName("-nep_error_relative","Print relative errors of each eigenpair","NEPErrorView",NULL);

    194:     if (nep->ops->setfromoptions) (*nep->ops->setfromoptions)(PetscOptionsObject,nep);
    195:     PetscObjectProcessOptionsHandlers(PetscOptionsObject,(PetscObject)nep);
    196:   ierr = PetscOptionsEnd();

    198:   if (!nep->V) NEPGetBV(nep,&nep->V);
    199:   BVSetFromOptions(nep->V);
    200:   if (!nep->rg) NEPGetRG(nep,&nep->rg);
    201:   RGSetFromOptions(nep->rg);
    202:   if (nep->useds) {
    203:     if (!nep->ds) NEPGetDS(nep,&nep->ds);
    204:     DSSetFromOptions(nep->ds);
    205:   }
    206:   if (!nep->refineksp) NEPRefineGetKSP(nep,&nep->refineksp);
    207:   KSPSetFromOptions(nep->refineksp);
    208:   if (nep->fui==NEP_USER_INTERFACE_SPLIT) for (i=0;i<nep->nt;i++) FNSetFromOptions(nep->f[i]);
    209:   PetscFunctionReturn(0);
    210: }

    212: /*@C
    213:    NEPGetTolerances - Gets the tolerance and maximum iteration count used
    214:    by the NEP convergence tests.

    216:    Not Collective

    218:    Input Parameter:
    219: .  nep - the nonlinear eigensolver context

    221:    Output Parameters:
    222: +  tol - the convergence tolerance
    223: -  maxits - maximum number of iterations

    225:    Notes:
    226:    The user can specify NULL for any parameter that is not needed.

    228:    Level: intermediate

    230: .seealso: NEPSetTolerances()
    231: @*/
    232: PetscErrorCode NEPGetTolerances(NEP nep,PetscReal *tol,PetscInt *maxits)
    233: {
    235:   if (tol)    *tol    = nep->tol;
    236:   if (maxits) *maxits = nep->max_it;
    237:   PetscFunctionReturn(0);
    238: }

    240: /*@
    241:    NEPSetTolerances - Sets the tolerance and maximum iteration count used
    242:    by the NEP convergence tests.

    244:    Logically Collective on nep

    246:    Input Parameters:
    247: +  nep    - the nonlinear eigensolver context
    248: .  tol    - the convergence tolerance
    249: -  maxits - maximum number of iterations to use

    251:    Options Database Keys:
    252: +  -nep_tol <tol> - Sets the convergence tolerance
    253: -  -nep_max_it <maxits> - Sets the maximum number of iterations allowed

    255:    Notes:
    256:    Use PETSC_DEFAULT for either argument to assign a reasonably good value.

    258:    Level: intermediate

    260: .seealso: NEPGetTolerances()
    261: @*/
    262: PetscErrorCode NEPSetTolerances(NEP nep,PetscReal tol,PetscInt maxits)
    263: {
    267:   if (tol == PETSC_DEFAULT) {
    268:     nep->tol   = PETSC_DEFAULT;
    269:     nep->state = NEP_STATE_INITIAL;
    270:   } else {
    272:     nep->tol = tol;
    273:   }
    274:   if (maxits == PETSC_DEFAULT || maxits == PETSC_DECIDE) {
    275:     nep->max_it = PETSC_DEFAULT;
    276:     nep->state  = NEP_STATE_INITIAL;
    277:   } else {
    279:     nep->max_it = maxits;
    280:   }
    281:   PetscFunctionReturn(0);
    282: }

    284: /*@C
    285:    NEPGetDimensions - Gets the number of eigenvalues to compute
    286:    and the dimension of the subspace.

    288:    Not Collective

    290:    Input Parameter:
    291: .  nep - the nonlinear eigensolver context

    293:    Output Parameters:
    294: +  nev - number of eigenvalues to compute
    295: .  ncv - the maximum dimension of the subspace to be used by the solver
    296: -  mpd - the maximum dimension allowed for the projected problem

    298:    Notes:
    299:    The user can specify NULL for any parameter that is not needed.

    301:    Level: intermediate

    303: .seealso: NEPSetDimensions()
    304: @*/
    305: PetscErrorCode NEPGetDimensions(NEP nep,PetscInt *nev,PetscInt *ncv,PetscInt *mpd)
    306: {
    308:   if (nev) *nev = nep->nev;
    309:   if (ncv) *ncv = nep->ncv;
    310:   if (mpd) *mpd = nep->mpd;
    311:   PetscFunctionReturn(0);
    312: }

    314: /*@
    315:    NEPSetDimensions - Sets the number of eigenvalues to compute
    316:    and the dimension of the subspace.

    318:    Logically Collective on nep

    320:    Input Parameters:
    321: +  nep - the nonlinear eigensolver context
    322: .  nev - number of eigenvalues to compute
    323: .  ncv - the maximum dimension of the subspace to be used by the solver
    324: -  mpd - the maximum dimension allowed for the projected problem

    326:    Options Database Keys:
    327: +  -nep_nev <nev> - Sets the number of eigenvalues
    328: .  -nep_ncv <ncv> - Sets the dimension of the subspace
    329: -  -nep_mpd <mpd> - Sets the maximum projected dimension

    331:    Notes:
    332:    Use PETSC_DEFAULT for ncv and mpd to assign a reasonably good value, which is
    333:    dependent on the solution method.

    335:    The parameters ncv and mpd are intimately related, so that the user is advised
    336:    to set one of them at most. Normal usage is that
    337:    (a) in cases where nev is small, the user sets ncv (a reasonable default is 2*nev); and
    338:    (b) in cases where nev is large, the user sets mpd.

    340:    The value of ncv should always be between nev and (nev+mpd), typically
    341:    ncv=nev+mpd. If nev is not too large, mpd=nev is a reasonable choice, otherwise
    342:    a smaller value should be used.

    344:    Level: intermediate

    346: .seealso: NEPGetDimensions()
    347: @*/
    348: PetscErrorCode NEPSetDimensions(NEP nep,PetscInt nev,PetscInt ncv,PetscInt mpd)
    349: {
    355:   nep->nev = nev;
    356:   if (ncv == PETSC_DECIDE || ncv == PETSC_DEFAULT) {
    357:     nep->ncv = PETSC_DEFAULT;
    358:   } else {
    360:     nep->ncv = ncv;
    361:   }
    362:   if (mpd == PETSC_DECIDE || mpd == PETSC_DEFAULT) {
    363:     nep->mpd = PETSC_DEFAULT;
    364:   } else {
    366:     nep->mpd = mpd;
    367:   }
    368:   nep->state = NEP_STATE_INITIAL;
    369:   PetscFunctionReturn(0);
    370: }

    372: /*@
    373:     NEPSetWhichEigenpairs - Specifies which portion of the spectrum is
    374:     to be sought.

    376:     Logically Collective on nep

    378:     Input Parameters:
    379: +   nep   - eigensolver context obtained from NEPCreate()
    380: -   which - the portion of the spectrum to be sought

    382:     Possible values:
    383:     The parameter 'which' can have one of these values

    385: +     NEP_LARGEST_MAGNITUDE - largest eigenvalues in magnitude (default)
    386: .     NEP_SMALLEST_MAGNITUDE - smallest eigenvalues in magnitude
    387: .     NEP_LARGEST_REAL - largest real parts
    388: .     NEP_SMALLEST_REAL - smallest real parts
    389: .     NEP_LARGEST_IMAGINARY - largest imaginary parts
    390: .     NEP_SMALLEST_IMAGINARY - smallest imaginary parts
    391: .     NEP_TARGET_MAGNITUDE - eigenvalues closest to the target (in magnitude)
    392: .     NEP_TARGET_REAL - eigenvalues with real part closest to target
    393: .     NEP_TARGET_IMAGINARY - eigenvalues with imaginary part closest to target
    394: .     NEP_ALL - all eigenvalues contained in a given region
    395: -     NEP_WHICH_USER - user defined ordering set with NEPSetEigenvalueComparison()

    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:     stated above. If SLEPc is compiled for real numbers NEP_LARGEST_IMAGINARY
    412:     and NEP_SMALLEST_IMAGINARY use the absolute value of the imaginary part
    413:     for eigenvalue selection.

    415:     The target is a scalar value provided with NEPSetTarget().

    417:     NEP_ALL is intended for use in the context of the CISS solver for
    418:     computing all eigenvalues in a region.

    420:     Level: intermediate

    422: .seealso: NEPGetWhichEigenpairs(), NEPSetTarget(), NEPSetEigenvalueComparison(), NEPWhich
    423: @*/
    424: PetscErrorCode NEPSetWhichEigenpairs(NEP nep,NEPWhich which)
    425: {
    428:   switch (which) {
    429:     case NEP_LARGEST_MAGNITUDE:
    430:     case NEP_SMALLEST_MAGNITUDE:
    431:     case NEP_LARGEST_REAL:
    432:     case NEP_SMALLEST_REAL:
    433:     case NEP_LARGEST_IMAGINARY:
    434:     case NEP_SMALLEST_IMAGINARY:
    435:     case NEP_TARGET_MAGNITUDE:
    436:     case NEP_TARGET_REAL:
    437: #if defined(PETSC_USE_COMPLEX)
    438:     case NEP_TARGET_IMAGINARY:
    439: #endif
    440:     case NEP_ALL:
    441:     case NEP_WHICH_USER:
    442:       if (nep->which != which) {
    443:         nep->state = NEP_STATE_INITIAL;
    444:         nep->which = which;
    445:       }
    446:       break;
    447: #if !defined(PETSC_USE_COMPLEX)
    448:     case NEP_TARGET_IMAGINARY:
    449:       SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_SUP,"NEP_TARGET_IMAGINARY can be used only with complex scalars");
    450: #endif
    451:     default:
    452:       SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'which' value");
    453:   }
    454:   PetscFunctionReturn(0);
    455: }

    457: /*@
    458:     NEPGetWhichEigenpairs - Returns which portion of the spectrum is to be
    459:     sought.

    461:     Not Collective

    463:     Input Parameter:
    464: .   nep - eigensolver context obtained from NEPCreate()

    466:     Output Parameter:
    467: .   which - the portion of the spectrum to be sought

    469:     Notes:
    470:     See NEPSetWhichEigenpairs() for possible values of 'which'.

    472:     Level: intermediate

    474: .seealso: NEPSetWhichEigenpairs(), NEPWhich
    475: @*/
    476: PetscErrorCode NEPGetWhichEigenpairs(NEP nep,NEPWhich *which)
    477: {
    480:   *which = nep->which;
    481:   PetscFunctionReturn(0);
    482: }

    484: /*@C
    485:    NEPSetEigenvalueComparison - Specifies the eigenvalue comparison function
    486:    when NEPSetWhichEigenpairs() is set to NEP_WHICH_USER.

    488:    Logically Collective on nep

    490:    Input Parameters:
    491: +  nep  - eigensolver context obtained from NEPCreate()
    492: .  func - a pointer to the comparison function
    493: -  ctx  - a context pointer (the last parameter to the comparison function)

    495:    Calling Sequence of func:
    496: $   func(PetscScalar ar,PetscScalar ai,PetscScalar br,PetscScalar bi,PetscInt *res,void *ctx)

    498: +   ar     - real part of the 1st eigenvalue
    499: .   ai     - imaginary part of the 1st eigenvalue
    500: .   br     - real part of the 2nd eigenvalue
    501: .   bi     - imaginary part of the 2nd eigenvalue
    502: .   res    - result of comparison
    503: -   ctx    - optional context, as set by NEPSetEigenvalueComparison()

    505:    Note:
    506:    The returning parameter 'res' can be
    507: +  negative - if the 1st eigenvalue is preferred to the 2st one
    508: .  zero     - if both eigenvalues are equally preferred
    509: -  positive - if the 2st eigenvalue is preferred to the 1st one

    511:    Level: advanced

    513: .seealso: NEPSetWhichEigenpairs(), NEPWhich
    514: @*/
    515: PetscErrorCode NEPSetEigenvalueComparison(NEP nep,PetscErrorCode (*func)(PetscScalar,PetscScalar,PetscScalar,PetscScalar,PetscInt*,void*),void* ctx)
    516: {
    518:   nep->sc->comparison    = func;
    519:   nep->sc->comparisonctx = ctx;
    520:   nep->which             = NEP_WHICH_USER;
    521:   PetscFunctionReturn(0);
    522: }

    524: /*@
    525:    NEPSetProblemType - Specifies the type of the nonlinear eigenvalue problem.

    527:    Logically Collective on nep

    529:    Input Parameters:
    530: +  nep  - the nonlinear eigensolver context
    531: -  type - a known type of nonlinear eigenvalue problem

    533:    Options Database Keys:
    534: +  -nep_general - general problem with no particular structure
    535: -  -nep_rational - a rational eigenvalue problem defined in split form with all f_i rational

    537:    Notes:
    538:    Allowed values for the problem type are general (NEP_GENERAL), and rational
    539:    (NEP_RATIONAL).

    541:    This function is used to provide a hint to the NEP solver to exploit certain
    542:    properties of the nonlinear eigenproblem. This hint may be used or not,
    543:    depending on the solver. By default, no particular structure is assumed.

    545:    Level: intermediate

    547: .seealso: NEPSetType(), NEPGetProblemType(), NEPProblemType
    548: @*/
    549: PetscErrorCode NEPSetProblemType(NEP nep,NEPProblemType type)
    550: {
    554:   if (type != nep->problem_type) {
    555:     nep->problem_type = type;
    556:     nep->state = NEP_STATE_INITIAL;
    557:   }
    558:   PetscFunctionReturn(0);
    559: }

    561: /*@
    562:    NEPGetProblemType - Gets the problem type from the NEP object.

    564:    Not Collective

    566:    Input Parameter:
    567: .  nep - the nonlinear eigensolver context

    569:    Output Parameter:
    570: .  type - the problem type

    572:    Level: intermediate

    574: .seealso: NEPSetProblemType(), NEPProblemType
    575: @*/
    576: PetscErrorCode NEPGetProblemType(NEP nep,NEPProblemType *type)
    577: {
    580:   *type = nep->problem_type;
    581:   PetscFunctionReturn(0);
    582: }

    584: /*@
    585:    NEPSetTwoSided - Sets the solver to use a two-sided variant so that left
    586:    eigenvectors are also computed.

    588:    Logically Collective on nep

    590:    Input Parameters:
    591: +  nep      - the eigensolver context
    592: -  twosided - whether the two-sided variant is to be used or not

    594:    Options Database Keys:
    595: .  -nep_two_sided <boolean> - Sets/resets the twosided flag

    597:    Notes:
    598:    If the user sets twosided=PETSC_TRUE then the solver uses a variant of
    599:    the algorithm that computes both right and left eigenvectors. This is
    600:    usually much more costly. This option is not available in all solvers.

    602:    When using two-sided solvers, the problem matrices must have both the
    603:    MatMult and MatMultTranspose operations defined.

    605:    Level: advanced

    607: .seealso: NEPGetTwoSided(), NEPGetLeftEigenvector()
    608: @*/
    609: PetscErrorCode NEPSetTwoSided(NEP nep,PetscBool twosided)
    610: {
    613:   if (twosided!=nep->twosided) {
    614:     nep->twosided = twosided;
    615:     nep->state    = NEP_STATE_INITIAL;
    616:   }
    617:   PetscFunctionReturn(0);
    618: }

    620: /*@
    621:    NEPGetTwoSided - Returns the flag indicating whether a two-sided variant
    622:    of the algorithm is being used or not.

    624:    Not Collective

    626:    Input Parameter:
    627: .  nep - the eigensolver context

    629:    Output Parameter:
    630: .  twosided - the returned flag

    632:    Level: advanced

    634: .seealso: NEPSetTwoSided()
    635: @*/
    636: PetscErrorCode NEPGetTwoSided(NEP nep,PetscBool *twosided)
    637: {
    640:   *twosided = nep->twosided;
    641:   PetscFunctionReturn(0);
    642: }

    644: /*@C
    645:    NEPSetConvergenceTestFunction - Sets a function to compute the error estimate
    646:    used in the convergence test.

    648:    Logically Collective on nep

    650:    Input Parameters:
    651: +  nep     - nonlinear eigensolver context obtained from NEPCreate()
    652: .  func    - a pointer to the convergence test function
    653: .  ctx     - context for private data for the convergence routine (may be null)
    654: -  destroy - a routine for destroying the context (may be null)

    656:    Calling Sequence of func:
    657: $   func(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)

    659: +   nep    - nonlinear eigensolver context obtained from NEPCreate()
    660: .   eigr   - real part of the eigenvalue
    661: .   eigi   - imaginary part of the eigenvalue
    662: .   res    - residual norm associated to the eigenpair
    663: .   errest - (output) computed error estimate
    664: -   ctx    - optional context, as set by NEPSetConvergenceTestFunction()

    666:    Note:
    667:    If the error estimate returned by the convergence test function is less than
    668:    the tolerance, then the eigenvalue is accepted as converged.

    670:    Level: advanced

    672: .seealso: NEPSetConvergenceTest(), NEPSetTolerances()
    673: @*/
    674: PetscErrorCode NEPSetConvergenceTestFunction(NEP nep,PetscErrorCode (*func)(NEP,PetscScalar,PetscScalar,PetscReal,PetscReal*,void*),void* ctx,PetscErrorCode (*destroy)(void*))
    675: {
    677:   if (nep->convergeddestroy) (*nep->convergeddestroy)(nep->convergedctx);
    678:   nep->convergeduser    = func;
    679:   nep->convergeddestroy = destroy;
    680:   nep->convergedctx     = ctx;
    681:   if (func == NEPConvergedRelative) nep->conv = NEP_CONV_REL;
    682:   else if (func == NEPConvergedNorm) nep->conv = NEP_CONV_NORM;
    683:   else if (func == NEPConvergedAbsolute) nep->conv = NEP_CONV_ABS;
    684:   else {
    685:     nep->conv      = NEP_CONV_USER;
    686:     nep->converged = nep->convergeduser;
    687:   }
    688:   PetscFunctionReturn(0);
    689: }

    691: /*@
    692:    NEPSetConvergenceTest - Specifies how to compute the error estimate
    693:    used in the convergence test.

    695:    Logically Collective on nep

    697:    Input Parameters:
    698: +  nep  - nonlinear eigensolver context obtained from NEPCreate()
    699: -  conv - the type of convergence test

    701:    Options Database Keys:
    702: +  -nep_conv_abs  - Sets the absolute convergence test
    703: .  -nep_conv_rel  - Sets the convergence test relative to the eigenvalue
    704: -  -nep_conv_user - Selects the user-defined convergence test

    706:    Note:
    707:    The parameter 'conv' can have one of these values
    708: +     NEP_CONV_ABS  - absolute error ||r||
    709: .     NEP_CONV_REL  - error relative to the eigenvalue l, ||r||/|l|
    710: .     NEP_CONV_NORM - error relative matrix norms, ||r||/sum_i(|f_i(l)|*||A_i||)
    711: -     NEP_CONV_USER - function set by NEPSetConvergenceTestFunction()

    713:    Level: intermediate

    715: .seealso: NEPGetConvergenceTest(), NEPSetConvergenceTestFunction(), NEPSetStoppingTest(), NEPConv
    716: @*/
    717: PetscErrorCode NEPSetConvergenceTest(NEP nep,NEPConv conv)
    718: {
    721:   switch (conv) {
    722:     case NEP_CONV_ABS:  nep->converged = NEPConvergedAbsolute; break;
    723:     case NEP_CONV_REL:  nep->converged = NEPConvergedRelative; break;
    724:     case NEP_CONV_NORM: nep->converged = NEPConvergedNorm; break;
    725:     case NEP_CONV_USER:
    727:       nep->converged = nep->convergeduser;
    728:       break;
    729:     default:
    730:       SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'conv' value");
    731:   }
    732:   nep->conv = conv;
    733:   PetscFunctionReturn(0);
    734: }

    736: /*@
    737:    NEPGetConvergenceTest - Gets the method used to compute the error estimate
    738:    used in the convergence test.

    740:    Not Collective

    742:    Input Parameters:
    743: .  nep   - nonlinear eigensolver context obtained from NEPCreate()

    745:    Output Parameters:
    746: .  conv  - the type of convergence test

    748:    Level: intermediate

    750: .seealso: NEPSetConvergenceTest(), NEPConv
    751: @*/
    752: PetscErrorCode NEPGetConvergenceTest(NEP nep,NEPConv *conv)
    753: {
    756:   *conv = nep->conv;
    757:   PetscFunctionReturn(0);
    758: }

    760: /*@C
    761:    NEPSetStoppingTestFunction - Sets a function to decide when to stop the outer
    762:    iteration of the eigensolver.

    764:    Logically Collective on nep

    766:    Input Parameters:
    767: +  nep     - nonlinear eigensolver context obtained from NEPCreate()
    768: .  func    - pointer to the stopping test function
    769: .  ctx     - context for private data for the stopping routine (may be null)
    770: -  destroy - a routine for destroying the context (may be null)

    772:    Calling Sequence of func:
    773: $   func(NEP nep,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nev,NEPConvergedReason *reason,void *ctx)

    775: +   nep    - nonlinear eigensolver context obtained from NEPCreate()
    776: .   its    - current number of iterations
    777: .   max_it - maximum number of iterations
    778: .   nconv  - number of currently converged eigenpairs
    779: .   nev    - number of requested eigenpairs
    780: .   reason - (output) result of the stopping test
    781: -   ctx    - optional context, as set by NEPSetStoppingTestFunction()

    783:    Note:
    784:    Normal usage is to first call the default routine NEPStoppingBasic() and then
    785:    set reason to NEP_CONVERGED_USER if some user-defined conditions have been
    786:    met. To let the eigensolver continue iterating, the result must be left as
    787:    NEP_CONVERGED_ITERATING.

    789:    Level: advanced

    791: .seealso: NEPSetStoppingTest(), NEPStoppingBasic()
    792: @*/
    793: PetscErrorCode NEPSetStoppingTestFunction(NEP nep,PetscErrorCode (*func)(NEP,PetscInt,PetscInt,PetscInt,PetscInt,NEPConvergedReason*,void*),void* ctx,PetscErrorCode (*destroy)(void*))
    794: {
    796:   if (nep->stoppingdestroy) (*nep->stoppingdestroy)(nep->stoppingctx);
    797:   nep->stoppinguser    = func;
    798:   nep->stoppingdestroy = destroy;
    799:   nep->stoppingctx     = ctx;
    800:   if (func == NEPStoppingBasic) nep->stop = NEP_STOP_BASIC;
    801:   else {
    802:     nep->stop     = NEP_STOP_USER;
    803:     nep->stopping = nep->stoppinguser;
    804:   }
    805:   PetscFunctionReturn(0);
    806: }

    808: /*@
    809:    NEPSetStoppingTest - Specifies how to decide the termination of the outer
    810:    loop of the eigensolver.

    812:    Logically Collective on nep

    814:    Input Parameters:
    815: +  nep  - nonlinear eigensolver context obtained from NEPCreate()
    816: -  stop - the type of stopping test

    818:    Options Database Keys:
    819: +  -nep_stop_basic - Sets the default stopping test
    820: -  -nep_stop_user  - Selects the user-defined stopping test

    822:    Note:
    823:    The parameter 'stop' can have one of these values
    824: +     NEP_STOP_BASIC - default stopping test
    825: -     NEP_STOP_USER  - function set by NEPSetStoppingTestFunction()

    827:    Level: advanced

    829: .seealso: NEPGetStoppingTest(), NEPSetStoppingTestFunction(), NEPSetConvergenceTest(), NEPStop
    830: @*/
    831: PetscErrorCode NEPSetStoppingTest(NEP nep,NEPStop stop)
    832: {
    835:   switch (stop) {
    836:     case NEP_STOP_BASIC: nep->stopping = NEPStoppingBasic; break;
    837:     case NEP_STOP_USER:
    839:       nep->stopping = nep->stoppinguser;
    840:       break;
    841:     default:
    842:       SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'stop' value");
    843:   }
    844:   nep->stop = stop;
    845:   PetscFunctionReturn(0);
    846: }

    848: /*@
    849:    NEPGetStoppingTest - Gets the method used to decide the termination of the outer
    850:    loop of the eigensolver.

    852:    Not Collective

    854:    Input Parameters:
    855: .  nep   - nonlinear eigensolver context obtained from NEPCreate()

    857:    Output Parameters:
    858: .  stop  - the type of stopping test

    860:    Level: advanced

    862: .seealso: NEPSetStoppingTest(), NEPStop
    863: @*/
    864: PetscErrorCode NEPGetStoppingTest(NEP nep,NEPStop *stop)
    865: {
    868:   *stop = nep->stop;
    869:   PetscFunctionReturn(0);
    870: }

    872: /*@
    873:    NEPSetTrackAll - Specifies if the solver must compute the residual of all
    874:    approximate eigenpairs or not.

    876:    Logically Collective on nep

    878:    Input Parameters:
    879: +  nep      - the eigensolver context
    880: -  trackall - whether compute all residuals or not

    882:    Notes:
    883:    If the user sets trackall=PETSC_TRUE then the solver explicitly computes
    884:    the residual for each eigenpair approximation. Computing the residual is
    885:    usually an expensive operation and solvers commonly compute the associated
    886:    residual to the first unconverged eigenpair.

    888:    The option '-nep_monitor_all' automatically activates this option.

    890:    Level: developer

    892: .seealso: NEPGetTrackAll()
    893: @*/
    894: PetscErrorCode NEPSetTrackAll(NEP nep,PetscBool trackall)
    895: {
    898:   nep->trackall = trackall;
    899:   PetscFunctionReturn(0);
    900: }

    902: /*@
    903:    NEPGetTrackAll - Returns the flag indicating whether all residual norms must
    904:    be computed or not.

    906:    Not Collective

    908:    Input Parameter:
    909: .  nep - the eigensolver context

    911:    Output Parameter:
    912: .  trackall - the returned flag

    914:    Level: developer

    916: .seealso: NEPSetTrackAll()
    917: @*/
    918: PetscErrorCode NEPGetTrackAll(NEP nep,PetscBool *trackall)
    919: {
    922:   *trackall = nep->trackall;
    923:   PetscFunctionReturn(0);
    924: }

    926: /*@
    927:    NEPSetRefine - Specifies the refinement type (and options) to be used
    928:    after the solve.

    930:    Logically Collective on nep

    932:    Input Parameters:
    933: +  nep    - the nonlinear eigensolver context
    934: .  refine - refinement type
    935: .  npart  - number of partitions of the communicator
    936: .  tol    - the convergence tolerance
    937: .  its    - maximum number of refinement iterations
    938: -  scheme - which scheme to be used for solving the involved linear systems

    940:    Options Database Keys:
    941: +  -nep_refine <type> - refinement type, one of <none,simple,multiple>
    942: .  -nep_refine_partitions <n> - the number of partitions
    943: .  -nep_refine_tol <tol> - the tolerance
    944: .  -nep_refine_its <its> - number of iterations
    945: -  -nep_refine_scheme - to set the scheme for the linear solves

    947:    Notes:
    948:    By default, iterative refinement is disabled, since it may be very
    949:    costly. There are two possible refinement strategies, simple and multiple.
    950:    The simple approach performs iterative refinement on each of the
    951:    converged eigenpairs individually, whereas the multiple strategy works
    952:    with the invariant pair as a whole, refining all eigenpairs simultaneously.
    953:    The latter may be required for the case of multiple eigenvalues.

    955:    In some cases, especially when using direct solvers within the
    956:    iterative refinement method, it may be helpful for improved scalability
    957:    to split the communicator in several partitions. The npart parameter
    958:    indicates how many partitions to use (defaults to 1).

    960:    The tol and its parameters specify the stopping criterion. In the simple
    961:    method, refinement continues until the residual of each eigenpair is
    962:    below the tolerance (tol defaults to the NEP tol, but may be set to a
    963:    different value). In contrast, the multiple method simply performs its
    964:    refinement iterations (just one by default).

    966:    The scheme argument is used to change the way in which linear systems are
    967:    solved. Possible choices are explicit, mixed block elimination (MBE),
    968:    and Schur complement.

    970:    Level: intermediate

    972: .seealso: NEPGetRefine()
    973: @*/
    974: PetscErrorCode NEPSetRefine(NEP nep,NEPRefine refine,PetscInt npart,PetscReal tol,PetscInt its,NEPRefineScheme scheme)
    975: {
    976:   PetscMPIInt    size;

    984:   nep->refine = refine;
    985:   if (refine) {  /* process parameters only if not REFINE_NONE */
    986:     if (npart!=nep->npart) {
    987:       PetscSubcommDestroy(&nep->refinesubc);
    988:       KSPDestroy(&nep->refineksp);
    989:     }
    990:     if (npart == PETSC_DEFAULT || npart == PETSC_DECIDE) {
    991:       nep->npart = 1;
    992:     } else {
    993:       MPI_Comm_size(PetscObjectComm((PetscObject)nep),&size);
    995:       nep->npart = npart;
    996:     }
    997:     if (tol == PETSC_DEFAULT || tol == PETSC_DECIDE) {
    998:       nep->rtol = PETSC_DEFAULT;
    999:     } else {
    1001:       nep->rtol = tol;
    1002:     }
    1003:     if (its==PETSC_DECIDE || its==PETSC_DEFAULT) {
    1004:       nep->rits = PETSC_DEFAULT;
    1005:     } else {
    1007:       nep->rits = its;
    1008:     }
    1009:     nep->scheme = scheme;
    1010:   }
    1011:   nep->state = NEP_STATE_INITIAL;
    1012:   PetscFunctionReturn(0);
    1013: }

    1015: /*@C
    1016:    NEPGetRefine - Gets the refinement strategy used by the NEP object, and the
    1017:    associated parameters.

    1019:    Not Collective

    1021:    Input Parameter:
    1022: .  nep - the nonlinear eigensolver context

    1024:    Output Parameters:
    1025: +  refine - refinement type
    1026: .  npart  - number of partitions of the communicator
    1027: .  tol    - the convergence tolerance
    1028: .  its    - maximum number of refinement iterations
    1029: -  scheme - the scheme used for solving linear systems

    1031:    Level: intermediate

    1033:    Note:
    1034:    The user can specify NULL for any parameter that is not needed.

    1036: .seealso: NEPSetRefine()
    1037: @*/
    1038: PetscErrorCode NEPGetRefine(NEP nep,NEPRefine *refine,PetscInt *npart,PetscReal *tol,PetscInt *its,NEPRefineScheme *scheme)
    1039: {
    1041:   if (refine) *refine = nep->refine;
    1042:   if (npart)  *npart  = nep->npart;
    1043:   if (tol)    *tol    = nep->rtol;
    1044:   if (its)    *its    = nep->rits;
    1045:   if (scheme) *scheme = nep->scheme;
    1046:   PetscFunctionReturn(0);
    1047: }

    1049: /*@C
    1050:    NEPSetOptionsPrefix - Sets the prefix used for searching for all
    1051:    NEP options in the database.

    1053:    Logically Collective on nep

    1055:    Input Parameters:
    1056: +  nep - the nonlinear eigensolver context
    1057: -  prefix - the prefix string to prepend to all NEP option requests

    1059:    Notes:
    1060:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    1061:    The first character of all runtime options is AUTOMATICALLY the
    1062:    hyphen.

    1064:    For example, to distinguish between the runtime options for two
    1065:    different NEP contexts, one could call
    1066: .vb
    1067:       NEPSetOptionsPrefix(nep1,"neig1_")
    1068:       NEPSetOptionsPrefix(nep2,"neig2_")
    1069: .ve

    1071:    Level: advanced

    1073: .seealso: NEPAppendOptionsPrefix(), NEPGetOptionsPrefix()
    1074: @*/
    1075: PetscErrorCode NEPSetOptionsPrefix(NEP nep,const char *prefix)
    1076: {
    1078:   if (!nep->V) NEPGetBV(nep,&nep->V);
    1079:   BVSetOptionsPrefix(nep->V,prefix);
    1080:   if (!nep->ds) NEPGetDS(nep,&nep->ds);
    1081:   DSSetOptionsPrefix(nep->ds,prefix);
    1082:   if (!nep->rg) NEPGetRG(nep,&nep->rg);
    1083:   RGSetOptionsPrefix(nep->rg,prefix);
    1084:   PetscObjectSetOptionsPrefix((PetscObject)nep,prefix);
    1085:   PetscFunctionReturn(0);
    1086: }

    1088: /*@C
    1089:    NEPAppendOptionsPrefix - Appends to the prefix used for searching for all
    1090:    NEP options in the database.

    1092:    Logically Collective on nep

    1094:    Input Parameters:
    1095: +  nep - the nonlinear eigensolver context
    1096: -  prefix - the prefix string to prepend to all NEP option requests

    1098:    Notes:
    1099:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    1100:    The first character of all runtime options is AUTOMATICALLY the hyphen.

    1102:    Level: advanced

    1104: .seealso: NEPSetOptionsPrefix(), NEPGetOptionsPrefix()
    1105: @*/
    1106: PetscErrorCode NEPAppendOptionsPrefix(NEP nep,const char *prefix)
    1107: {
    1109:   if (!nep->V) NEPGetBV(nep,&nep->V);
    1110:   BVAppendOptionsPrefix(nep->V,prefix);
    1111:   if (!nep->ds) NEPGetDS(nep,&nep->ds);
    1112:   DSAppendOptionsPrefix(nep->ds,prefix);
    1113:   if (!nep->rg) NEPGetRG(nep,&nep->rg);
    1114:   RGAppendOptionsPrefix(nep->rg,prefix);
    1115:   PetscObjectAppendOptionsPrefix((PetscObject)nep,prefix);
    1116:   PetscFunctionReturn(0);
    1117: }

    1119: /*@C
    1120:    NEPGetOptionsPrefix - Gets the prefix used for searching for all
    1121:    NEP options in the database.

    1123:    Not Collective

    1125:    Input Parameters:
    1126: .  nep - the nonlinear eigensolver context

    1128:    Output Parameters:
    1129: .  prefix - pointer to the prefix string used is returned

    1131:    Note:
    1132:    On the Fortran side, the user should pass in a string 'prefix' of
    1133:    sufficient length to hold the prefix.

    1135:    Level: advanced

    1137: .seealso: NEPSetOptionsPrefix(), NEPAppendOptionsPrefix()
    1138: @*/
    1139: PetscErrorCode NEPGetOptionsPrefix(NEP nep,const char *prefix[])
    1140: {
    1143:   PetscObjectGetOptionsPrefix((PetscObject)nep,prefix);
    1144:   PetscFunctionReturn(0);
    1145: }