Actual source code: nepopts.c
slepc-3.21.1 2024-04-26
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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

     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:   PetscFunctionBegin;
     48:   PetscCall(PetscOptionsGetViewer(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(PetscOptionsRestoreViewer(&viewer));
     62:   PetscCall(NEPMonitorSet(nep,mfunc,vf,(PetscErrorCode(*)(void **))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 set the solver type.

     72:    Collective

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

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

     80:    Level: beginner

     82: .seealso: 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_DEFAULT?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: /*@C
    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: 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:    Notes:
    259:    Use PETSC_DEFAULT for either argument to assign a reasonably good value.

    261:    Level: intermediate

    263: .seealso: NEPGetTolerances()
    264: @*/
    265: PetscErrorCode NEPSetTolerances(NEP nep,PetscReal tol,PetscInt maxits)
    266: {
    267:   PetscFunctionBegin;
    271:   if (tol == (PetscReal)PETSC_DEFAULT) {
    272:     nep->tol   = PETSC_DEFAULT;
    273:     nep->state = NEP_STATE_INITIAL;
    274:   } else {
    275:     PetscCheck(tol>0.0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of tol. Must be > 0");
    276:     nep->tol = tol;
    277:   }
    278:   if (maxits == PETSC_DEFAULT || maxits == PETSC_DECIDE) {
    279:     nep->max_it = PETSC_DEFAULT;
    280:     nep->state  = NEP_STATE_INITIAL;
    281:   } else {
    282:     PetscCheck(maxits>0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of maxits. Must be > 0");
    283:     nep->max_it = maxits;
    284:   }
    285:   PetscFunctionReturn(PETSC_SUCCESS);
    286: }

    288: /*@C
    289:    NEPGetDimensions - Gets the number of eigenvalues to compute
    290:    and the dimension of the subspace.

    292:    Not Collective

    294:    Input Parameter:
    295: .  nep - the nonlinear eigensolver context

    297:    Output Parameters:
    298: +  nev - number of eigenvalues to compute
    299: .  ncv - the maximum dimension of the subspace to be used by the solver
    300: -  mpd - the maximum dimension allowed for the projected problem

    302:    Notes:
    303:    The user can specify NULL for any parameter that is not needed.

    305:    Level: intermediate

    307: .seealso: NEPSetDimensions()
    308: @*/
    309: PetscErrorCode NEPGetDimensions(NEP nep,PetscInt *nev,PetscInt *ncv,PetscInt *mpd)
    310: {
    311:   PetscFunctionBegin;
    313:   if (nev) *nev = nep->nev;
    314:   if (ncv) *ncv = nep->ncv;
    315:   if (mpd) *mpd = nep->mpd;
    316:   PetscFunctionReturn(PETSC_SUCCESS);
    317: }

    319: /*@
    320:    NEPSetDimensions - Sets the number of eigenvalues to compute
    321:    and the dimension of the subspace.

    323:    Logically Collective

    325:    Input Parameters:
    326: +  nep - the nonlinear eigensolver context
    327: .  nev - number of eigenvalues to compute
    328: .  ncv - the maximum dimension of the subspace to be used by the solver
    329: -  mpd - the maximum dimension allowed for the projected problem

    331:    Options Database Keys:
    332: +  -nep_nev <nev> - Sets the number of eigenvalues
    333: .  -nep_ncv <ncv> - Sets the dimension of the subspace
    334: -  -nep_mpd <mpd> - Sets the maximum projected dimension

    336:    Notes:
    337:    Use PETSC_DEFAULT for ncv and mpd to assign a reasonably good value, which is
    338:    dependent on the solution method.

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

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

    349:    Level: intermediate

    351: .seealso: NEPGetDimensions()
    352: @*/
    353: PetscErrorCode NEPSetDimensions(NEP nep,PetscInt nev,PetscInt ncv,PetscInt mpd)
    354: {
    355:   PetscFunctionBegin;
    360:   PetscCheck(nev>0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of nev. Must be > 0");
    361:   nep->nev = nev;
    362:   if (ncv == PETSC_DECIDE || ncv == PETSC_DEFAULT) {
    363:     nep->ncv = PETSC_DEFAULT;
    364:   } else {
    365:     PetscCheck(ncv>0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of ncv. Must be > 0");
    366:     nep->ncv = ncv;
    367:   }
    368:   if (mpd == PETSC_DECIDE || mpd == PETSC_DEFAULT) {
    369:     nep->mpd = PETSC_DEFAULT;
    370:   } else {
    371:     PetscCheck(mpd>0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of mpd. Must be > 0");
    372:     nep->mpd = mpd;
    373:   }
    374:   nep->state = NEP_STATE_INITIAL;
    375:   PetscFunctionReturn(PETSC_SUCCESS);
    376: }

    378: /*@
    379:     NEPSetWhichEigenpairs - Specifies which portion of the spectrum is
    380:     to be sought.

    382:     Logically Collective

    384:     Input Parameters:
    385: +   nep   - eigensolver context obtained from NEPCreate()
    386: -   which - the portion of the spectrum to be sought

    388:     Options Database Keys:
    389: +   -nep_largest_magnitude - Sets largest eigenvalues in magnitude
    390: .   -nep_smallest_magnitude - Sets smallest eigenvalues in magnitude
    391: .   -nep_largest_real - Sets largest real parts
    392: .   -nep_smallest_real - Sets smallest real parts
    393: .   -nep_largest_imaginary - Sets largest imaginary parts
    394: .   -nep_smallest_imaginary - Sets smallest imaginary parts
    395: .   -nep_target_magnitude - Sets eigenvalues closest to target
    396: .   -nep_target_real - Sets real parts closest to target
    397: .   -nep_target_imaginary - Sets imaginary parts closest to target
    398: -   -nep_all - Sets all eigenvalues in a region

    400:     Notes:
    401:     The parameter 'which' can have one of these values

    403: +     NEP_LARGEST_MAGNITUDE - largest eigenvalues in magnitude (default)
    404: .     NEP_SMALLEST_MAGNITUDE - smallest eigenvalues in magnitude
    405: .     NEP_LARGEST_REAL - largest real parts
    406: .     NEP_SMALLEST_REAL - smallest real parts
    407: .     NEP_LARGEST_IMAGINARY - largest imaginary parts
    408: .     NEP_SMALLEST_IMAGINARY - smallest imaginary parts
    409: .     NEP_TARGET_MAGNITUDE - eigenvalues closest to the target (in magnitude)
    410: .     NEP_TARGET_REAL - eigenvalues with real part closest to target
    411: .     NEP_TARGET_IMAGINARY - eigenvalues with imaginary part closest to target
    412: .     NEP_ALL - all eigenvalues contained in a given region
    413: -     NEP_WHICH_USER - user defined ordering set with NEPSetEigenvalueComparison()

    415:     Not all eigensolvers implemented in NEP account for all the possible values
    416:     stated above. If SLEPc is compiled for real numbers NEP_LARGEST_IMAGINARY
    417:     and NEP_SMALLEST_IMAGINARY use the absolute value of the imaginary part
    418:     for eigenvalue selection.

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

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

    425:     Level: intermediate

    427: .seealso: NEPGetWhichEigenpairs(), NEPSetTarget(), NEPSetEigenvalueComparison(), NEPWhich
    428: @*/
    429: PetscErrorCode NEPSetWhichEigenpairs(NEP nep,NEPWhich which)
    430: {
    431:   PetscFunctionBegin;
    434:   switch (which) {
    435:     case NEP_LARGEST_MAGNITUDE:
    436:     case NEP_SMALLEST_MAGNITUDE:
    437:     case NEP_LARGEST_REAL:
    438:     case NEP_SMALLEST_REAL:
    439:     case NEP_LARGEST_IMAGINARY:
    440:     case NEP_SMALLEST_IMAGINARY:
    441:     case NEP_TARGET_MAGNITUDE:
    442:     case NEP_TARGET_REAL:
    443: #if defined(PETSC_USE_COMPLEX)
    444:     case NEP_TARGET_IMAGINARY:
    445: #endif
    446:     case NEP_ALL:
    447:     case NEP_WHICH_USER:
    448:       if (nep->which != which) {
    449:         nep->state = NEP_STATE_INITIAL;
    450:         nep->which = which;
    451:       }
    452:       break;
    453: #if !defined(PETSC_USE_COMPLEX)
    454:     case NEP_TARGET_IMAGINARY:
    455:       SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_SUP,"NEP_TARGET_IMAGINARY can be used only with complex scalars");
    456: #endif
    457:     default:
    458:       SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'which' value");
    459:   }
    460:   PetscFunctionReturn(PETSC_SUCCESS);
    461: }

    463: /*@
    464:     NEPGetWhichEigenpairs - Returns which portion of the spectrum is to be
    465:     sought.

    467:     Not Collective

    469:     Input Parameter:
    470: .   nep - eigensolver context obtained from NEPCreate()

    472:     Output Parameter:
    473: .   which - the portion of the spectrum to be sought

    475:     Notes:
    476:     See NEPSetWhichEigenpairs() for possible values of 'which'.

    478:     Level: intermediate

    480: .seealso: NEPSetWhichEigenpairs(), NEPWhich
    481: @*/
    482: PetscErrorCode NEPGetWhichEigenpairs(NEP nep,NEPWhich *which)
    483: {
    484:   PetscFunctionBegin;
    486:   PetscAssertPointer(which,2);
    487:   *which = nep->which;
    488:   PetscFunctionReturn(PETSC_SUCCESS);
    489: }

    491: /*@C
    492:    NEPSetEigenvalueComparison - Specifies the eigenvalue comparison function
    493:    when NEPSetWhichEigenpairs() is set to NEP_WHICH_USER.

    495:    Logically Collective

    497:    Input Parameters:
    498: +  nep  - eigensolver context obtained from NEPCreate()
    499: .  comp - a pointer to the comparison function
    500: -  ctx  - a context pointer (the last parameter to the comparison function)

    502:    Calling sequence of comp:
    503: $  PetscErrorCode comp(PetscScalar ar,PetscScalar ai,PetscScalar br,PetscScalar bi,PetscInt *res,void *ctx)
    504: +   ar     - real part of the 1st eigenvalue
    505: .   ai     - imaginary part of the 1st eigenvalue
    506: .   br     - real part of the 2nd eigenvalue
    507: .   bi     - imaginary part of the 2nd eigenvalue
    508: .   res    - result of comparison
    509: -   ctx    - optional context, as set by NEPSetEigenvalueComparison()

    511:    Note:
    512:    The returning parameter 'res' can be
    513: +  negative - if the 1st eigenvalue is preferred to the 2st one
    514: .  zero     - if both eigenvalues are equally preferred
    515: -  positive - if the 2st eigenvalue is preferred to the 1st one

    517:    Level: advanced

    519: .seealso: NEPSetWhichEigenpairs(), NEPWhich
    520: @*/
    521: PetscErrorCode NEPSetEigenvalueComparison(NEP nep,PetscErrorCode (*comp)(PetscScalar ar,PetscScalar ai,PetscScalar br,PetscScalar bi,PetscInt *res,void *ctx),void* ctx)
    522: {
    523:   PetscFunctionBegin;
    525:   nep->sc->comparison    = comp;
    526:   nep->sc->comparisonctx = ctx;
    527:   nep->which             = NEP_WHICH_USER;
    528:   PetscFunctionReturn(PETSC_SUCCESS);
    529: }

    531: /*@
    532:    NEPSetProblemType - Specifies the type of the nonlinear eigenvalue problem.

    534:    Logically Collective

    536:    Input Parameters:
    537: +  nep  - the nonlinear eigensolver context
    538: -  type - a known type of nonlinear eigenvalue problem

    540:    Options Database Keys:
    541: +  -nep_general - general problem with no particular structure
    542: -  -nep_rational - a rational eigenvalue problem defined in split form with all f_i rational

    544:    Notes:
    545:    Allowed values for the problem type are general (NEP_GENERAL), and rational
    546:    (NEP_RATIONAL).

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

    552:    Level: intermediate

    554: .seealso: NEPSetType(), NEPGetProblemType(), NEPProblemType
    555: @*/
    556: PetscErrorCode NEPSetProblemType(NEP nep,NEPProblemType type)
    557: {
    558:   PetscFunctionBegin;
    561:   PetscCheck(type==NEP_GENERAL || type==NEP_RATIONAL,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_WRONG,"Unknown eigenvalue problem type");
    562:   if (type != nep->problem_type) {
    563:     nep->problem_type = type;
    564:     nep->state = NEP_STATE_INITIAL;
    565:   }
    566:   PetscFunctionReturn(PETSC_SUCCESS);
    567: }

    569: /*@
    570:    NEPGetProblemType - Gets the problem type from the NEP object.

    572:    Not Collective

    574:    Input Parameter:
    575: .  nep - the nonlinear eigensolver context

    577:    Output Parameter:
    578: .  type - the problem type

    580:    Level: intermediate

    582: .seealso: NEPSetProblemType(), NEPProblemType
    583: @*/
    584: PetscErrorCode NEPGetProblemType(NEP nep,NEPProblemType *type)
    585: {
    586:   PetscFunctionBegin;
    588:   PetscAssertPointer(type,2);
    589:   *type = nep->problem_type;
    590:   PetscFunctionReturn(PETSC_SUCCESS);
    591: }

    593: /*@
    594:    NEPSetTwoSided - Sets the solver to use a two-sided variant so that left
    595:    eigenvectors are also computed.

    597:    Logically Collective

    599:    Input Parameters:
    600: +  nep      - the eigensolver context
    601: -  twosided - whether the two-sided variant is to be used or not

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

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

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

    614:    Level: advanced

    616: .seealso: NEPGetTwoSided(), NEPGetLeftEigenvector()
    617: @*/
    618: PetscErrorCode NEPSetTwoSided(NEP nep,PetscBool twosided)
    619: {
    620:   PetscFunctionBegin;
    623:   if (twosided!=nep->twosided) {
    624:     nep->twosided = twosided;
    625:     nep->state    = NEP_STATE_INITIAL;
    626:   }
    627:   PetscFunctionReturn(PETSC_SUCCESS);
    628: }

    630: /*@
    631:    NEPGetTwoSided - Returns the flag indicating whether a two-sided variant
    632:    of the algorithm is being used or not.

    634:    Not Collective

    636:    Input Parameter:
    637: .  nep - the eigensolver context

    639:    Output Parameter:
    640: .  twosided - the returned flag

    642:    Level: advanced

    644: .seealso: NEPSetTwoSided()
    645: @*/
    646: PetscErrorCode NEPGetTwoSided(NEP nep,PetscBool *twosided)
    647: {
    648:   PetscFunctionBegin;
    650:   PetscAssertPointer(twosided,2);
    651:   *twosided = nep->twosided;
    652:   PetscFunctionReturn(PETSC_SUCCESS);
    653: }

    655: /*@C
    656:    NEPSetConvergenceTestFunction - Sets a function to compute the error estimate
    657:    used in the convergence test.

    659:    Logically Collective

    661:    Input Parameters:
    662: +  nep     - nonlinear eigensolver context obtained from NEPCreate()
    663: .  conv    - a pointer to the convergence test function
    664: .  ctx     - context for private data for the convergence routine (may be null)
    665: -  destroy - a routine for destroying the context (may be null)

    667:    Calling sequence of conv:
    668: $  PetscErrorCode conv(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
    669: +   nep    - nonlinear eigensolver context obtained from NEPCreate()
    670: .   eigr   - real part of the eigenvalue
    671: .   eigi   - imaginary part of the eigenvalue
    672: .   res    - residual norm associated to the eigenpair
    673: .   errest - (output) computed error estimate
    674: -   ctx    - optional context, as set by NEPSetConvergenceTestFunction()

    676:    Note:
    677:    If the error estimate returned by the convergence test function is less than
    678:    the tolerance, then the eigenvalue is accepted as converged.

    680:    Level: advanced

    682: .seealso: NEPSetConvergenceTest(), NEPSetTolerances()
    683: @*/
    684: PetscErrorCode NEPSetConvergenceTestFunction(NEP nep,PetscErrorCode (*conv)(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx),void* ctx,PetscErrorCode (*destroy)(void*))
    685: {
    686:   PetscFunctionBegin;
    688:   if (nep->convergeddestroy) PetscCall((*nep->convergeddestroy)(nep->convergedctx));
    689:   nep->convergeduser    = conv;
    690:   nep->convergeddestroy = destroy;
    691:   nep->convergedctx     = ctx;
    692:   if (conv == NEPConvergedRelative) nep->conv = NEP_CONV_REL;
    693:   else if (conv == NEPConvergedNorm) nep->conv = NEP_CONV_NORM;
    694:   else if (conv == NEPConvergedAbsolute) nep->conv = NEP_CONV_ABS;
    695:   else {
    696:     nep->conv      = NEP_CONV_USER;
    697:     nep->converged = nep->convergeduser;
    698:   }
    699:   PetscFunctionReturn(PETSC_SUCCESS);
    700: }

    702: /*@
    703:    NEPSetConvergenceTest - Specifies how to compute the error estimate
    704:    used in the convergence test.

    706:    Logically Collective

    708:    Input Parameters:
    709: +  nep  - nonlinear eigensolver context obtained from NEPCreate()
    710: -  conv - the type of convergence test

    712:    Options Database Keys:
    713: +  -nep_conv_abs  - Sets the absolute convergence test
    714: .  -nep_conv_rel  - Sets the convergence test relative to the eigenvalue
    715: -  -nep_conv_user - Selects the user-defined convergence test

    717:    Note:
    718:    The parameter 'conv' can have one of these values
    719: +     NEP_CONV_ABS  - absolute error ||r||
    720: .     NEP_CONV_REL  - error relative to the eigenvalue l, ||r||/|l|
    721: .     NEP_CONV_NORM - error relative matrix norms, ||r||/sum_i(|f_i(l)|*||A_i||)
    722: -     NEP_CONV_USER - function set by NEPSetConvergenceTestFunction()

    724:    Level: intermediate

    726: .seealso: NEPGetConvergenceTest(), NEPSetConvergenceTestFunction(), NEPSetStoppingTest(), NEPConv
    727: @*/
    728: PetscErrorCode NEPSetConvergenceTest(NEP nep,NEPConv conv)
    729: {
    730:   PetscFunctionBegin;
    733:   switch (conv) {
    734:     case NEP_CONV_ABS:  nep->converged = NEPConvergedAbsolute; break;
    735:     case NEP_CONV_REL:  nep->converged = NEPConvergedRelative; break;
    736:     case NEP_CONV_NORM: nep->converged = NEPConvergedNorm; break;
    737:     case NEP_CONV_USER:
    738:       PetscCheck(nep->convergeduser,PetscObjectComm((PetscObject)nep),PETSC_ERR_ORDER,"Must call NEPSetConvergenceTestFunction() first");
    739:       nep->converged = nep->convergeduser;
    740:       break;
    741:     default:
    742:       SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'conv' value");
    743:   }
    744:   nep->conv = conv;
    745:   PetscFunctionReturn(PETSC_SUCCESS);
    746: }

    748: /*@
    749:    NEPGetConvergenceTest - Gets the method used to compute the error estimate
    750:    used in the convergence test.

    752:    Not Collective

    754:    Input Parameters:
    755: .  nep   - nonlinear eigensolver context obtained from NEPCreate()

    757:    Output Parameters:
    758: .  conv  - the type of convergence test

    760:    Level: intermediate

    762: .seealso: NEPSetConvergenceTest(), NEPConv
    763: @*/
    764: PetscErrorCode NEPGetConvergenceTest(NEP nep,NEPConv *conv)
    765: {
    766:   PetscFunctionBegin;
    768:   PetscAssertPointer(conv,2);
    769:   *conv = nep->conv;
    770:   PetscFunctionReturn(PETSC_SUCCESS);
    771: }

    773: /*@C
    774:    NEPSetStoppingTestFunction - Sets a function to decide when to stop the outer
    775:    iteration of the eigensolver.

    777:    Logically Collective

    779:    Input Parameters:
    780: +  nep     - nonlinear eigensolver context obtained from NEPCreate()
    781: .  stop    - pointer to the stopping test function
    782: .  ctx     - context for private data for the stopping routine (may be null)
    783: -  destroy - a routine for destroying the context (may be null)

    785:    Calling sequence of stop:
    786: $  PetscErrorCode stop(NEP nep,PetscInt its,PetscInt max_its,PetscInt nconv,PetscInt nev,NEPConvergedReason *reason,void *ctx)
    787: +   nep    - nonlinear eigensolver context obtained from NEPCreate()
    788: .   its    - current number of iterations
    789: .   max_its - maximum number of iterations
    790: .   nconv  - number of currently converged eigenpairs
    791: .   nev    - number of requested eigenpairs
    792: .   reason - (output) result of the stopping test
    793: -   ctx    - optional context, as set by NEPSetStoppingTestFunction()

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

    801:    Level: advanced

    803: .seealso: NEPSetStoppingTest(), NEPStoppingBasic()
    804: @*/
    805: PetscErrorCode NEPSetStoppingTestFunction(NEP nep,PetscErrorCode (*stop)(NEP nep,PetscInt its,PetscInt max_its,PetscInt nconv,PetscInt nev,NEPConvergedReason *reason,void *ctx),void* ctx,PetscErrorCode (*destroy)(void*))
    806: {
    807:   PetscFunctionBegin;
    809:   if (nep->stoppingdestroy) PetscCall((*nep->stoppingdestroy)(nep->stoppingctx));
    810:   nep->stoppinguser    = stop;
    811:   nep->stoppingdestroy = destroy;
    812:   nep->stoppingctx     = ctx;
    813:   if (stop == NEPStoppingBasic) nep->stop = NEP_STOP_BASIC;
    814:   else {
    815:     nep->stop     = NEP_STOP_USER;
    816:     nep->stopping = nep->stoppinguser;
    817:   }
    818:   PetscFunctionReturn(PETSC_SUCCESS);
    819: }

    821: /*@
    822:    NEPSetStoppingTest - Specifies how to decide the termination of the outer
    823:    loop of the eigensolver.

    825:    Logically Collective

    827:    Input Parameters:
    828: +  nep  - nonlinear eigensolver context obtained from NEPCreate()
    829: -  stop - the type of stopping test

    831:    Options Database Keys:
    832: +  -nep_stop_basic - Sets the default stopping test
    833: -  -nep_stop_user  - Selects the user-defined stopping test

    835:    Note:
    836:    The parameter 'stop' can have one of these values
    837: +     NEP_STOP_BASIC - default stopping test
    838: -     NEP_STOP_USER  - function set by NEPSetStoppingTestFunction()

    840:    Level: advanced

    842: .seealso: NEPGetStoppingTest(), NEPSetStoppingTestFunction(), NEPSetConvergenceTest(), NEPStop
    843: @*/
    844: PetscErrorCode NEPSetStoppingTest(NEP nep,NEPStop stop)
    845: {
    846:   PetscFunctionBegin;
    849:   switch (stop) {
    850:     case NEP_STOP_BASIC: nep->stopping = NEPStoppingBasic; break;
    851:     case NEP_STOP_USER:
    852:       PetscCheck(nep->stoppinguser,PetscObjectComm((PetscObject)nep),PETSC_ERR_ORDER,"Must call NEPSetStoppingTestFunction() first");
    853:       nep->stopping = nep->stoppinguser;
    854:       break;
    855:     default:
    856:       SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'stop' value");
    857:   }
    858:   nep->stop = stop;
    859:   PetscFunctionReturn(PETSC_SUCCESS);
    860: }

    862: /*@
    863:    NEPGetStoppingTest - Gets the method used to decide the termination of the outer
    864:    loop of the eigensolver.

    866:    Not Collective

    868:    Input Parameters:
    869: .  nep   - nonlinear eigensolver context obtained from NEPCreate()

    871:    Output Parameters:
    872: .  stop  - the type of stopping test

    874:    Level: advanced

    876: .seealso: NEPSetStoppingTest(), NEPStop
    877: @*/
    878: PetscErrorCode NEPGetStoppingTest(NEP nep,NEPStop *stop)
    879: {
    880:   PetscFunctionBegin;
    882:   PetscAssertPointer(stop,2);
    883:   *stop = nep->stop;
    884:   PetscFunctionReturn(PETSC_SUCCESS);
    885: }

    887: /*@
    888:    NEPSetTrackAll - Specifies if the solver must compute the residual of all
    889:    approximate eigenpairs or not.

    891:    Logically Collective

    893:    Input Parameters:
    894: +  nep      - the eigensolver context
    895: -  trackall - whether compute all residuals or not

    897:    Notes:
    898:    If the user sets trackall=PETSC_TRUE then the solver explicitly computes
    899:    the residual for each eigenpair approximation. Computing the residual is
    900:    usually an expensive operation and solvers commonly compute the associated
    901:    residual to the first unconverged eigenpair.

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

    905:    Level: developer

    907: .seealso: NEPGetTrackAll()
    908: @*/
    909: PetscErrorCode NEPSetTrackAll(NEP nep,PetscBool trackall)
    910: {
    911:   PetscFunctionBegin;
    914:   nep->trackall = trackall;
    915:   PetscFunctionReturn(PETSC_SUCCESS);
    916: }

    918: /*@
    919:    NEPGetTrackAll - Returns the flag indicating whether all residual norms must
    920:    be computed or not.

    922:    Not Collective

    924:    Input Parameter:
    925: .  nep - the eigensolver context

    927:    Output Parameter:
    928: .  trackall - the returned flag

    930:    Level: developer

    932: .seealso: NEPSetTrackAll()
    933: @*/
    934: PetscErrorCode NEPGetTrackAll(NEP nep,PetscBool *trackall)
    935: {
    936:   PetscFunctionBegin;
    938:   PetscAssertPointer(trackall,2);
    939:   *trackall = nep->trackall;
    940:   PetscFunctionReturn(PETSC_SUCCESS);
    941: }

    943: /*@
    944:    NEPSetRefine - Specifies the refinement type (and options) to be used
    945:    after the solve.

    947:    Logically Collective

    949:    Input Parameters:
    950: +  nep    - the nonlinear eigensolver context
    951: .  refine - refinement type
    952: .  npart  - number of partitions of the communicator
    953: .  tol    - the convergence tolerance
    954: .  its    - maximum number of refinement iterations
    955: -  scheme - which scheme to be used for solving the involved linear systems

    957:    Options Database Keys:
    958: +  -nep_refine <type> - refinement type, one of <none,simple,multiple>
    959: .  -nep_refine_partitions <n> - the number of partitions
    960: .  -nep_refine_tol <tol> - the tolerance
    961: .  -nep_refine_its <its> - number of iterations
    962: -  -nep_refine_scheme - to set the scheme for the linear solves

    964:    Notes:
    965:    By default, iterative refinement is disabled, since it may be very
    966:    costly. There are two possible refinement strategies, simple and multiple.
    967:    The simple approach performs iterative refinement on each of the
    968:    converged eigenpairs individually, whereas the multiple strategy works
    969:    with the invariant pair as a whole, refining all eigenpairs simultaneously.
    970:    The latter may be required for the case of multiple eigenvalues.

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

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

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

    987:    Level: intermediate

    989: .seealso: NEPGetRefine()
    990: @*/
    991: PetscErrorCode NEPSetRefine(NEP nep,NEPRefine refine,PetscInt npart,PetscReal tol,PetscInt its,NEPRefineScheme scheme)
    992: {
    993:   PetscMPIInt    size;

    995:   PetscFunctionBegin;
    1002:   nep->refine = refine;
    1003:   if (refine) {  /* process parameters only if not REFINE_NONE */
    1004:     if (npart!=nep->npart) {
    1005:       PetscCall(PetscSubcommDestroy(&nep->refinesubc));
    1006:       PetscCall(KSPDestroy(&nep->refineksp));
    1007:     }
    1008:     if (npart == PETSC_DEFAULT || npart == PETSC_DECIDE) {
    1009:       nep->npart = 1;
    1010:     } else {
    1011:       PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)nep),&size));
    1012:       PetscCheck(npart>0 && npart<=size,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of npart");
    1013:       nep->npart = npart;
    1014:     }
    1015:     if (tol == (PetscReal)PETSC_DEFAULT || tol == (PetscReal)PETSC_DECIDE) {
    1016:       nep->rtol = PETSC_DEFAULT;
    1017:     } else {
    1018:       PetscCheck(tol>0.0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of tol. Must be > 0");
    1019:       nep->rtol = tol;
    1020:     }
    1021:     if (its==PETSC_DECIDE || its==PETSC_DEFAULT) {
    1022:       nep->rits = PETSC_DEFAULT;
    1023:     } else {
    1024:       PetscCheck(its>=0,PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of its. Must be >= 0");
    1025:       nep->rits = its;
    1026:     }
    1027:     nep->scheme = scheme;
    1028:   }
    1029:   nep->state = NEP_STATE_INITIAL;
    1030:   PetscFunctionReturn(PETSC_SUCCESS);
    1031: }

    1033: /*@C
    1034:    NEPGetRefine - Gets the refinement strategy used by the NEP object, and the
    1035:    associated parameters.

    1037:    Not Collective

    1039:    Input Parameter:
    1040: .  nep - the nonlinear eigensolver context

    1042:    Output Parameters:
    1043: +  refine - refinement type
    1044: .  npart  - number of partitions of the communicator
    1045: .  tol    - the convergence tolerance
    1046: .  its    - maximum number of refinement iterations
    1047: -  scheme - the scheme used for solving linear systems

    1049:    Level: intermediate

    1051:    Note:
    1052:    The user can specify NULL for any parameter that is not needed.

    1054: .seealso: NEPSetRefine()
    1055: @*/
    1056: PetscErrorCode NEPGetRefine(NEP nep,NEPRefine *refine,PetscInt *npart,PetscReal *tol,PetscInt *its,NEPRefineScheme *scheme)
    1057: {
    1058:   PetscFunctionBegin;
    1060:   if (refine) *refine = nep->refine;
    1061:   if (npart)  *npart  = nep->npart;
    1062:   if (tol)    *tol    = nep->rtol;
    1063:   if (its)    *its    = nep->rits;
    1064:   if (scheme) *scheme = nep->scheme;
    1065:   PetscFunctionReturn(PETSC_SUCCESS);
    1066: }

    1068: /*@C
    1069:    NEPSetOptionsPrefix - Sets the prefix used for searching for all
    1070:    NEP options in the database.

    1072:    Logically Collective

    1074:    Input Parameters:
    1075: +  nep - the nonlinear eigensolver context
    1076: -  prefix - the prefix string to prepend to all NEP option requests

    1078:    Notes:
    1079:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    1080:    The first character of all runtime options is AUTOMATICALLY the
    1081:    hyphen.

    1083:    For example, to distinguish between the runtime options for two
    1084:    different NEP contexts, one could call
    1085: .vb
    1086:       NEPSetOptionsPrefix(nep1,"neig1_")
    1087:       NEPSetOptionsPrefix(nep2,"neig2_")
    1088: .ve

    1090:    Level: advanced

    1092: .seealso: NEPAppendOptionsPrefix(), NEPGetOptionsPrefix()
    1093: @*/
    1094: PetscErrorCode NEPSetOptionsPrefix(NEP nep,const char *prefix)
    1095: {
    1096:   PetscFunctionBegin;
    1098:   if (!nep->V) PetscCall(NEPGetBV(nep,&nep->V));
    1099:   PetscCall(BVSetOptionsPrefix(nep->V,prefix));
    1100:   if (!nep->ds) PetscCall(NEPGetDS(nep,&nep->ds));
    1101:   PetscCall(DSSetOptionsPrefix(nep->ds,prefix));
    1102:   if (!nep->rg) PetscCall(NEPGetRG(nep,&nep->rg));
    1103:   PetscCall(RGSetOptionsPrefix(nep->rg,prefix));
    1104:   PetscCall(PetscObjectSetOptionsPrefix((PetscObject)nep,prefix));
    1105:   PetscFunctionReturn(PETSC_SUCCESS);
    1106: }

    1108: /*@C
    1109:    NEPAppendOptionsPrefix - Appends to the prefix used for searching for all
    1110:    NEP options in the database.

    1112:    Logically Collective

    1114:    Input Parameters:
    1115: +  nep - the nonlinear eigensolver context
    1116: -  prefix - the prefix string to prepend to all NEP option requests

    1118:    Notes:
    1119:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    1120:    The first character of all runtime options is AUTOMATICALLY the hyphen.

    1122:    Level: advanced

    1124: .seealso: NEPSetOptionsPrefix(), NEPGetOptionsPrefix()
    1125: @*/
    1126: PetscErrorCode NEPAppendOptionsPrefix(NEP nep,const char *prefix)
    1127: {
    1128:   PetscFunctionBegin;
    1130:   if (!nep->V) PetscCall(NEPGetBV(nep,&nep->V));
    1131:   PetscCall(BVAppendOptionsPrefix(nep->V,prefix));
    1132:   if (!nep->ds) PetscCall(NEPGetDS(nep,&nep->ds));
    1133:   PetscCall(DSAppendOptionsPrefix(nep->ds,prefix));
    1134:   if (!nep->rg) PetscCall(NEPGetRG(nep,&nep->rg));
    1135:   PetscCall(RGAppendOptionsPrefix(nep->rg,prefix));
    1136:   PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)nep,prefix));
    1137:   PetscFunctionReturn(PETSC_SUCCESS);
    1138: }

    1140: /*@C
    1141:    NEPGetOptionsPrefix - Gets the prefix used for searching for all
    1142:    NEP options in the database.

    1144:    Not Collective

    1146:    Input Parameters:
    1147: .  nep - the nonlinear eigensolver context

    1149:    Output Parameters:
    1150: .  prefix - pointer to the prefix string used is returned

    1152:    Note:
    1153:    On the Fortran side, the user should pass in a string 'prefix' of
    1154:    sufficient length to hold the prefix.

    1156:    Level: advanced

    1158: .seealso: NEPSetOptionsPrefix(), NEPAppendOptionsPrefix()
    1159: @*/
    1160: PetscErrorCode NEPGetOptionsPrefix(NEP nep,const char *prefix[])
    1161: {
    1162:   PetscFunctionBegin;
    1164:   PetscAssertPointer(prefix,2);
    1165:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)nep,prefix));
    1166:   PetscFunctionReturn(PETSC_SUCCESS);
    1167: }