Date: 2026-01-20T11:35:37+00:00

Actual source code: epsopts.c

      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain

      6:    This file is part of SLEPc.
      7:    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
      8:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      9: */
     10: /*
     11:    EPS routines related to options that can be set via the command-line
     12:    or procedurally.
     13: */

     15: #include <slepc/private/epsimpl.h>
     16: #include <petscdraw.h>

     18: /*@C
     19:    EPSMonitorSetFromOptions - Sets a monitor function and viewer appropriate for the type
     20:    indicated by the user.

     22:    Collective

     24:    Input Parameters:
     25: +  eps      - the linear eigensolver context
     26: .  opt      - the command line option for this monitor
     27: .  name     - the monitor type one is seeking
     28: .  ctx      - an optional user context for the monitor, or `NULL`
     29: -  trackall - whether this monitor tracks all eigenvalues or not

     31:    Level: developer

     33: .seealso: [](ch:eps), `EPSMonitorSet()`, `EPSSetTrackAll()`
     34: @*/
     35: PetscErrorCode EPSMonitorSetFromOptions(EPS eps,const char opt[],const char name[],void *ctx,PetscBool trackall)
     36: {
     37:   PetscErrorCode       (*mfunc)(EPS,PetscInt,PetscInt,PetscScalar*,PetscScalar*,PetscReal*,PetscInt,void*);
     38:   PetscErrorCode       (*cfunc)(PetscViewer,PetscViewerFormat,void*,PetscViewerAndFormat**);
     39:   PetscErrorCode       (*dfunc)(PetscViewerAndFormat**);
     40:   PetscViewerAndFormat *vf;
     41:   PetscViewer          viewer;
     42:   PetscViewerFormat    format;
     43:   PetscViewerType      vtype;
     44:   char                 key[PETSC_MAX_PATH_LEN];
     45:   PetscBool            flg;

     47:   PetscFunctionBegin;
     48:   PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)eps),((PetscObject)eps)->options,((PetscObject)eps)->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(EPSMonitorList,key,&mfunc));
     54:   PetscCheck(mfunc,PetscObjectComm((PetscObject)eps),PETSC_ERR_SUP,"Specified viewer and format not supported");
     55:   PetscCall(PetscFunctionListFind(EPSMonitorCreateList,key,&cfunc));
     56:   PetscCall(PetscFunctionListFind(EPSMonitorDestroyList,key,&dfunc));
     57:   if (!cfunc) cfunc = PetscViewerAndFormatCreate_Internal;
     58:   if (!dfunc) dfunc = PetscViewerAndFormatDestroy;

     60:   PetscCall((*cfunc)(viewer,format,ctx,&vf));
     61:   PetscCall(PetscViewerDestroy(&viewer));
     62:   PetscCall(EPSMonitorSet(eps,mfunc,vf,(PetscCtxDestroyFn*)dfunc));
     63:   if (trackall) PetscCall(EPSSetTrackAll(eps,PETSC_TRUE));
     64:   PetscFunctionReturn(PETSC_SUCCESS);
     65: }

     67: /*@
     68:    EPSSetFromOptions - Sets `EPS` options from the options database.
     69:    This routine must be called before `EPSSetUp()` if the user is to be
     70:    allowed to configure the solver.

     72:    Collective

     74:    Input Parameter:
     75: .  eps - the linear eigensolver context

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

     80:    Level: beginner

     82: .seealso: [](ch:eps), `EPSSetOptionsPrefix()`
     83: @*/
     84: PetscErrorCode EPSSetFromOptions(EPS eps)
     85: {
     86:   char           type[256];
     87:   PetscBool      set,flg,flg1,flg2,flg3,bval;
     88:   PetscReal      r,array[2]={0,0};
     89:   PetscScalar    s;
     90:   PetscInt       i,j,k;
     91:   EPSBalance     bal;

     93:   PetscFunctionBegin;
     95:   PetscCall(EPSRegisterAll());
     96:   PetscObjectOptionsBegin((PetscObject)eps);
     97:     PetscCall(PetscOptionsFList("-eps_type","Eigensolver method","EPSSetType",EPSList,(char*)(((PetscObject)eps)->type_name?((PetscObject)eps)->type_name:EPSKRYLOVSCHUR),type,sizeof(type),&flg));
     98:     if (flg) PetscCall(EPSSetType(eps,type));
     99:     else if (!((PetscObject)eps)->type_name) PetscCall(EPSSetType(eps,EPSKRYLOVSCHUR));

    101:     PetscCall(PetscOptionsBoolGroupBegin("-eps_hermitian","Hermitian eigenvalue problem","EPSSetProblemType",&flg));
    102:     if (flg) PetscCall(EPSSetProblemType(eps,EPS_HEP));
    103:     PetscCall(PetscOptionsBoolGroup("-eps_gen_hermitian","Generalized Hermitian eigenvalue problem","EPSSetProblemType",&flg));
    104:     if (flg) PetscCall(EPSSetProblemType(eps,EPS_GHEP));
    105:     PetscCall(PetscOptionsBoolGroup("-eps_non_hermitian","Non-Hermitian eigenvalue problem","EPSSetProblemType",&flg));
    106:     if (flg) PetscCall(EPSSetProblemType(eps,EPS_NHEP));
    107:     PetscCall(PetscOptionsBoolGroup("-eps_gen_non_hermitian","Generalized non-Hermitian eigenvalue problem","EPSSetProblemType",&flg));
    108:     if (flg) PetscCall(EPSSetProblemType(eps,EPS_GNHEP));
    109:     PetscCall(PetscOptionsBoolGroup("-eps_pos_gen_non_hermitian","Generalized non-Hermitian eigenvalue problem with positive semi-definite B","EPSSetProblemType",&flg));
    110:     if (flg) PetscCall(EPSSetProblemType(eps,EPS_PGNHEP));
    111:     PetscCall(PetscOptionsBoolGroup("-eps_gen_indefinite","Generalized Hermitian-indefinite eigenvalue problem","EPSSetProblemType",&flg));
    112:     if (flg) PetscCall(EPSSetProblemType(eps,EPS_GHIEP));
    113:     PetscCall(PetscOptionsBoolGroup("-eps_bse","Structured Bethe-Salpeter eigenvalue problem","EPSSetProblemType",&flg));
    114:     if (flg) PetscCall(EPSSetProblemType(eps,EPS_BSE));
    115:     PetscCall(PetscOptionsBoolGroupEnd("-eps_hamiltonian","Structured Hamiltonian eigenvalue problem","EPSSetProblemType",&flg));
    116:     if (flg) PetscCall(EPSSetProblemType(eps,EPS_HAMILT));

    118:     PetscCall(PetscOptionsBoolGroupBegin("-eps_ritz","Rayleigh-Ritz extraction","EPSSetExtraction",&flg));
    119:     if (flg) PetscCall(EPSSetExtraction(eps,EPS_RITZ));
    120:     PetscCall(PetscOptionsBoolGroup("-eps_harmonic","Harmonic Ritz extraction","EPSSetExtraction",&flg));
    121:     if (flg) PetscCall(EPSSetExtraction(eps,EPS_HARMONIC));
    122:     PetscCall(PetscOptionsBoolGroup("-eps_harmonic_relative","Relative harmonic Ritz extraction","EPSSetExtraction",&flg));
    123:     if (flg) PetscCall(EPSSetExtraction(eps,EPS_HARMONIC_RELATIVE));
    124:     PetscCall(PetscOptionsBoolGroup("-eps_harmonic_right","Right harmonic Ritz extraction","EPSSetExtraction",&flg));
    125:     if (flg) PetscCall(EPSSetExtraction(eps,EPS_HARMONIC_RIGHT));
    126:     PetscCall(PetscOptionsBoolGroup("-eps_harmonic_largest","Largest harmonic Ritz extraction","EPSSetExtraction",&flg));
    127:     if (flg) PetscCall(EPSSetExtraction(eps,EPS_HARMONIC_LARGEST));
    128:     PetscCall(PetscOptionsBoolGroup("-eps_refined","Refined Ritz extraction","EPSSetExtraction",&flg));
    129:     if (flg) PetscCall(EPSSetExtraction(eps,EPS_REFINED));
    130:     PetscCall(PetscOptionsBoolGroupEnd("-eps_refined_harmonic","Refined harmonic Ritz extraction","EPSSetExtraction",&flg));
    131:     if (flg) PetscCall(EPSSetExtraction(eps,EPS_REFINED_HARMONIC));

    133:     bal = eps->balance;
    134:     PetscCall(PetscOptionsEnum("-eps_balance","Balancing method","EPSSetBalance",EPSBalanceTypes,(PetscEnum)bal,(PetscEnum*)&bal,&flg1));
    135:     j = eps->balance_its;
    136:     PetscCall(PetscOptionsInt("-eps_balance_its","Number of iterations in balancing","EPSSetBalance",eps->balance_its,&j,&flg2));
    137:     r = eps->balance_cutoff;
    138:     PetscCall(PetscOptionsReal("-eps_balance_cutoff","Cutoff value in balancing","EPSSetBalance",eps->balance_cutoff,&r,&flg3));
    139:     if (flg1 || flg2 || flg3) PetscCall(EPSSetBalance(eps,bal,j,r));

    141:     i = eps->max_it;
    142:     PetscCall(PetscOptionsInt("-eps_max_it","Maximum number of iterations","EPSSetTolerances",eps->max_it,&i,&flg1));
    143:     r = eps->tol;
    144:     PetscCall(PetscOptionsReal("-eps_tol","Tolerance","EPSSetTolerances",SlepcDefaultTol(eps->tol),&r,&flg2));
    145:     if (flg1 || flg2) PetscCall(EPSSetTolerances(eps,r,i));

    147:     r = eps->thres;
    148:     PetscCall(PetscOptionsReal("-eps_threshold_absolute","Absolute threshold","EPSSetThreshold",r,&r,&flg));
    149:     if (flg) PetscCall(EPSSetThreshold(eps,r,PETSC_FALSE));
    150:     PetscCall(PetscOptionsReal("-eps_threshold_relative","Relative threshold","EPSSetThreshold",r,&r,&flg));
    151:     if (flg) PetscCall(EPSSetThreshold(eps,r,PETSC_TRUE));

    153:     PetscCall(PetscOptionsBoolGroupBegin("-eps_conv_rel","Relative error convergence test","EPSSetConvergenceTest",&flg));
    154:     if (flg) PetscCall(EPSSetConvergenceTest(eps,EPS_CONV_REL));
    155:     PetscCall(PetscOptionsBoolGroup("-eps_conv_norm","Convergence test relative to the eigenvalue and the matrix norms","EPSSetConvergenceTest",&flg));
    156:     if (flg) PetscCall(EPSSetConvergenceTest(eps,EPS_CONV_NORM));
    157:     PetscCall(PetscOptionsBoolGroup("-eps_conv_abs","Absolute error convergence test","EPSSetConvergenceTest",&flg));
    158:     if (flg) PetscCall(EPSSetConvergenceTest(eps,EPS_CONV_ABS));
    159:     PetscCall(PetscOptionsBoolGroupEnd("-eps_conv_user","User-defined convergence test","EPSSetConvergenceTest",&flg));
    160:     if (flg) PetscCall(EPSSetConvergenceTest(eps,EPS_CONV_USER));

    162:     PetscCall(PetscOptionsBoolGroupBegin("-eps_stop_basic","Stop iteration if all eigenvalues converged or max_it reached","EPSSetStoppingTest",&flg));
    163:     if (flg) PetscCall(EPSSetStoppingTest(eps,EPS_STOP_BASIC));
    164:     PetscCall(PetscOptionsBoolGroup("-eps_stop_threshold","Stop iteration if a converged eigenvalue is below/above the threshold","EPSSetStoppingTest",&flg));
    165:     if (flg) PetscCall(EPSSetStoppingTest(eps,EPS_STOP_THRESHOLD));
    166:     PetscCall(PetscOptionsBoolGroupEnd("-eps_stop_user","User-defined stopping test","EPSSetStoppingTest",&flg));
    167:     if (flg) PetscCall(EPSSetStoppingTest(eps,EPS_STOP_USER));

    169:     i = eps->nev;
    170:     PetscCall(PetscOptionsInt("-eps_nev","Number of eigenvalues to compute","EPSSetDimensions",eps->nev,&i,&flg1));
    171:     if (!flg1) i = PETSC_CURRENT;
    172:     j = eps->ncv;
    173:     PetscCall(PetscOptionsInt("-eps_ncv","Number of basis vectors","EPSSetDimensions",eps->ncv,&j,&flg2));
    174:     k = eps->mpd;
    175:     PetscCall(PetscOptionsInt("-eps_mpd","Maximum dimension of projected problem","EPSSetDimensions",eps->mpd,&k,&flg3));
    176:     if (flg1 || flg2 || flg3) PetscCall(EPSSetDimensions(eps,i,j,k));

    178:     PetscCall(PetscOptionsBoolGroupBegin("-eps_largest_magnitude","Compute largest eigenvalues in magnitude","EPSSetWhichEigenpairs",&flg));
    179:     if (flg) PetscCall(EPSSetWhichEigenpairs(eps,EPS_LARGEST_MAGNITUDE));
    180:     PetscCall(PetscOptionsBoolGroup("-eps_smallest_magnitude","Compute smallest eigenvalues in magnitude","EPSSetWhichEigenpairs",&flg));
    181:     if (flg) PetscCall(EPSSetWhichEigenpairs(eps,EPS_SMALLEST_MAGNITUDE));
    182:     PetscCall(PetscOptionsBoolGroup("-eps_largest_real","Compute eigenvalues with largest real parts","EPSSetWhichEigenpairs",&flg));
    183:     if (flg) PetscCall(EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL));
    184:     PetscCall(PetscOptionsBoolGroup("-eps_smallest_real","Compute eigenvalues with smallest real parts","EPSSetWhichEigenpairs",&flg));
    185:     if (flg) PetscCall(EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL));
    186:     PetscCall(PetscOptionsBoolGroup("-eps_largest_imaginary","Compute eigenvalues with largest imaginary parts","EPSSetWhichEigenpairs",&flg));
    187:     if (flg) PetscCall(EPSSetWhichEigenpairs(eps,EPS_LARGEST_IMAGINARY));
    188:     PetscCall(PetscOptionsBoolGroup("-eps_smallest_imaginary","Compute eigenvalues with smallest imaginary parts","EPSSetWhichEigenpairs",&flg));
    189:     if (flg) PetscCall(EPSSetWhichEigenpairs(eps,EPS_SMALLEST_IMAGINARY));
    190:     PetscCall(PetscOptionsBoolGroup("-eps_target_magnitude","Compute eigenvalues closest to target","EPSSetWhichEigenpairs",&flg));
    191:     if (flg) PetscCall(EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE));
    192:     PetscCall(PetscOptionsBoolGroup("-eps_target_real","Compute eigenvalues with real parts closest to target","EPSSetWhichEigenpairs",&flg));
    193:     if (flg) PetscCall(EPSSetWhichEigenpairs(eps,EPS_TARGET_REAL));
    194:     PetscCall(PetscOptionsBoolGroup("-eps_target_imaginary","Compute eigenvalues with imaginary parts closest to target","EPSSetWhichEigenpairs",&flg));
    195:     if (flg) PetscCall(EPSSetWhichEigenpairs(eps,EPS_TARGET_IMAGINARY));
    196:     PetscCall(PetscOptionsBoolGroupEnd("-eps_all","Compute all eigenvalues in an interval or a region","EPSSetWhichEigenpairs",&flg));
    197:     if (flg) PetscCall(EPSSetWhichEigenpairs(eps,EPS_ALL));

    199:     PetscCall(PetscOptionsScalar("-eps_target","Value of the target","EPSSetTarget",eps->target,&s,&flg));
    200:     if (flg) {
    201:       if (eps->which!=EPS_TARGET_REAL && eps->which!=EPS_TARGET_IMAGINARY) PetscCall(EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE));
    202:       PetscCall(EPSSetTarget(eps,s));
    203:     }

    205:     k = 2;
    206:     PetscCall(PetscOptionsRealArray("-eps_interval","Computational interval (two real values separated with a comma without spaces)","EPSSetInterval",array,&k,&flg));
    207:     if (flg) {
    208:       PetscCheck(k>1,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_SIZ,"Must pass two values in -eps_interval (comma-separated without spaces)");
    209:       PetscCall(EPSSetWhichEigenpairs(eps,EPS_ALL));
    210:       PetscCall(EPSSetInterval(eps,array[0],array[1]));
    211:     }

    213:     PetscCall(PetscOptionsBool("-eps_true_residual","Compute true residuals explicitly","EPSSetTrueResidual",eps->trueres,&eps->trueres,NULL));
    214:     PetscCall(PetscOptionsBool("-eps_purify","Postprocess eigenvectors for purification","EPSSetPurify",eps->purify,&bval,&flg));
    215:     if (flg) PetscCall(EPSSetPurify(eps,bval));
    216:     PetscCall(PetscOptionsBool("-eps_two_sided","Use two-sided variant (to compute left eigenvectors)","EPSSetTwoSided",eps->twosided,&bval,&flg));
    217:     if (flg) PetscCall(EPSSetTwoSided(eps,bval));

    219:     /* -----------------------------------------------------------------------*/
    220:     /*
    221:       Cancels all monitors hardwired into code before call to EPSSetFromOptions()
    222:     */
    223:     PetscCall(PetscOptionsBool("-eps_monitor_cancel","Remove any hardwired monitor routines","EPSMonitorCancel",PETSC_FALSE,&flg,&set));
    224:     if (set && flg) PetscCall(EPSMonitorCancel(eps));
    225:     PetscCall(EPSMonitorSetFromOptions(eps,"-eps_monitor","first_approximation",NULL,PETSC_FALSE));
    226:     PetscCall(EPSMonitorSetFromOptions(eps,"-eps_monitor_all","all_approximations",NULL,PETSC_TRUE));
    227:     PetscCall(EPSMonitorSetFromOptions(eps,"-eps_monitor_conv","convergence_history",NULL,PETSC_FALSE));

    229:     /* -----------------------------------------------------------------------*/
    230:     PetscCall(PetscOptionsName("-eps_view","Print detailed information on solver used","EPSView",&set));
    231:     PetscCall(PetscOptionsName("-eps_view_vectors","View computed eigenvectors","EPSVectorsView",&set));
    232:     PetscCall(PetscOptionsName("-eps_view_values","View computed eigenvalues","EPSValuesView",&set));
    233:     PetscCall(PetscOptionsName("-eps_converged_reason","Print reason for convergence, and number of iterations","EPSConvergedReasonView",&set));
    234:     PetscCall(PetscOptionsName("-eps_error_absolute","Print absolute errors of each eigenpair","EPSErrorView",&set));
    235:     PetscCall(PetscOptionsName("-eps_error_relative","Print relative errors of each eigenpair","EPSErrorView",&set));
    236:     PetscCall(PetscOptionsName("-eps_error_backward","Print backward errors of each eigenpair","EPSErrorView",&set));

    238:     PetscTryTypeMethod(eps,setfromoptions,PetscOptionsObject);
    239:     PetscCall(PetscObjectProcessOptionsHandlers((PetscObject)eps,PetscOptionsObject));
    240:   PetscOptionsEnd();

    242:   if (!eps->V) PetscCall(EPSGetBV(eps,&eps->V));
    243:   PetscCall(BVSetFromOptions(eps->V));
    244:   if (!eps->rg) PetscCall(EPSGetRG(eps,&eps->rg));
    245:   PetscCall(RGSetFromOptions(eps->rg));
    246:   if (eps->useds) {
    247:     if (!eps->ds) PetscCall(EPSGetDS(eps,&eps->ds));
    248:     PetscCall(EPSSetDSType(eps));
    249:     PetscCall(DSSetFromOptions(eps->ds));
    250:   }
    251:   if (!eps->st) PetscCall(EPSGetST(eps,&eps->st));
    252:   PetscCall(EPSSetDefaultST(eps));
    253:   PetscCall(STSetFromOptions(eps->st));
    254:   PetscFunctionReturn(PETSC_SUCCESS);
    255: }

    257: /*@
    258:    EPSGetTolerances - Gets the tolerance and maximum iteration count used
    259:    by the `EPS` convergence tests.

    261:    Not Collective

    263:    Input Parameter:
    264: .  eps - the linear eigensolver context

    266:    Output Parameters:
    267: +  tol - the convergence tolerance
    268: -  maxits - maximum number of iterations

    270:    Notes:
    271:    The user can specify `NULL` for any parameter that is not needed.

    273:    Level: intermediate

    275: .seealso: [](ch:eps), `EPSSetTolerances()`
    276: @*/
    277: PetscErrorCode EPSGetTolerances(EPS eps,PetscReal *tol,PetscInt *maxits)
    278: {
    279:   PetscFunctionBegin;
    281:   if (tol)    *tol    = eps->tol;
    282:   if (maxits) *maxits = eps->max_it;
    283:   PetscFunctionReturn(PETSC_SUCCESS);
    284: }

    286: /*@
    287:    EPSSetTolerances - Sets the tolerance and maximum iteration count used
    288:    by the `EPS` convergence tests.

    290:    Logically Collective

    292:    Input Parameters:
    293: +  eps    - the linear eigensolver context
    294: .  tol    - the convergence tolerance
    295: -  maxits - maximum number of iterations to use

    297:    Options Database Keys:
    298: +  -eps_tol \<tol\>       - sets the convergence tolerance
    299: -  -eps_max_it \<maxits\> - sets the maximum number of iterations allowed

    301:    Note:
    302:    Use `PETSC_CURRENT` to retain the current value of any of the parameters.
    303:    Use `PETSC_DETERMINE` for either argument to assign a default value computed
    304:    internally (may be different in each solver).
    305:    For `maxits` use `PETSC_UNLIMITED` to indicate there is no upper bound on this value.

    307:    Level: intermediate

    309: .seealso: [](ch:eps), `EPSGetTolerances()`
    310: @*/
    311: PetscErrorCode EPSSetTolerances(EPS eps,PetscReal tol,PetscInt maxits)
    312: {
    313:   PetscFunctionBegin;
    317:   if (tol == (PetscReal)PETSC_DETERMINE) {
    318:     eps->tol   = PETSC_DETERMINE;
    319:     eps->state = EPS_STATE_INITIAL;
    320:   } else if (tol != (PetscReal)PETSC_CURRENT) {
    321:     PetscCheck(tol>0.0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of tol. Must be > 0");
    322:     eps->tol = tol;
    323:   }
    324:   if (maxits == PETSC_DETERMINE) {
    325:     eps->max_it = PETSC_DETERMINE;
    326:     eps->state  = EPS_STATE_INITIAL;
    327:   } else if (maxits == PETSC_UNLIMITED) {
    328:     eps->max_it = PETSC_INT_MAX;
    329:   } else if (maxits != PETSC_CURRENT) {
    330:     PetscCheck(maxits>0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of maxits. Must be > 0");
    331:     eps->max_it = maxits;
    332:   }
    333:   PetscFunctionReturn(PETSC_SUCCESS);
    334: }

    336: /*@
    337:    EPSGetDimensions - Gets the number of eigenvalues to compute
    338:    and the dimension of the subspace.

    340:    Not Collective

    342:    Input Parameter:
    343: .  eps - the linear eigensolver context

    345:    Output Parameters:
    346: +  nev - number of eigenvalues to compute
    347: .  ncv - the maximum dimension of the subspace to be used by the solver
    348: -  mpd - the maximum dimension allowed for the projected problem

    350:    Level: intermediate

    352: .seealso: [](ch:eps), `EPSSetDimensions()`
    353: @*/
    354: PetscErrorCode EPSGetDimensions(EPS eps,PetscInt *nev,PetscInt *ncv,PetscInt *mpd)
    355: {
    356:   PetscFunctionBegin;
    358:   if (nev) *nev = eps->nev? eps->nev: 1;
    359:   if (ncv) *ncv = eps->ncv;
    360:   if (mpd) *mpd = eps->mpd;
    361:   PetscFunctionReturn(PETSC_SUCCESS);
    362: }

    364: /*@
    365:    EPSSetDimensions - Sets the number of eigenvalues to compute
    366:    and the dimension of the subspace.

    368:    Logically Collective

    370:    Input Parameters:
    371: +  eps - the linear eigensolver context
    372: .  nev - number of eigenvalues to compute
    373: .  ncv - the maximum dimension of the subspace to be used by the solver
    374: -  mpd - the maximum dimension allowed for the projected problem

    376:    Options Database Keys:
    377: +  -eps_nev \<nev\> - sets the number of eigenvalues
    378: .  -eps_ncv \<ncv\> - sets the dimension of the subspace
    379: -  -eps_mpd \<mpd\> - sets the maximum projected dimension

    381:    Notes:
    382:    Use `PETSC_DETERMINE` for `ncv` and `mpd` to assign a reasonably good value, which is
    383:    dependent on the solution method. For any of the arguments, use `PETSC_CURRENT`
    384:    to preserve the current value.

    386:    The parameters `ncv` and `mpd` are intimately related, so that the user is advised
    387:    to set one of them at most. Normal usage is\:

    389:     1. In cases where `nev` is small, the user sets `ncv` (a reasonable default is `2*nev`).
    390:     2. In cases where `nev` is large, the user sets `mpd`.

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

    396:    When computing all eigenvalues in an interval, see `EPSSetInterval()`, these
    397:    parameters lose relevance, and tuning must be done with
    398:    `EPSKrylovSchurSetDimensions()`.

    400:    Level: intermediate

    402: .seealso: [](ch:eps), `EPSGetDimensions()`, `EPSSetInterval()`, `EPSKrylovSchurSetDimensions()`
    403: @*/
    404: PetscErrorCode EPSSetDimensions(EPS eps,PetscInt nev,PetscInt ncv,PetscInt mpd)
    405: {
    406:   PetscFunctionBegin;
    411:   if (nev != PETSC_CURRENT) {
    412:     PetscCheck(nev>0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of nev. Must be > 0");
    413:     eps->nev = nev;
    414:   }
    415:   if (ncv == PETSC_DETERMINE) {
    416:     eps->ncv = PETSC_DETERMINE;
    417:   } else if (ncv != PETSC_CURRENT) {
    418:     PetscCheck(ncv>0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of ncv. Must be > 0");
    419:     eps->ncv = ncv;
    420:   }
    421:   if (mpd == PETSC_DETERMINE) {
    422:     eps->mpd = PETSC_DETERMINE;
    423:   } else if (mpd != PETSC_CURRENT) {
    424:     PetscCheck(mpd>0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of mpd. Must be > 0");
    425:     eps->mpd = mpd;
    426:   }
    427:   eps->state = EPS_STATE_INITIAL;
    428:   PetscFunctionReturn(PETSC_SUCCESS);
    429: }

    431: /*@
    432:    EPSSetWhichEigenpairs - Specifies which portion of the spectrum is
    433:    to be sought.

    435:    Logically Collective

    437:    Input Parameters:
    438: +  eps   - the linear eigensolver context
    439: -  which - the portion of the spectrum to be sought, see `EPSWhich` for possible values

    441:    Options Database Keys:
    442: +  -eps_largest_magnitude  - sets largest eigenvalues in magnitude
    443: .  -eps_smallest_magnitude - sets smallest eigenvalues in magnitude
    444: .  -eps_largest_real       - sets largest real parts
    445: .  -eps_smallest_real      - sets smallest real parts
    446: .  -eps_largest_imaginary  - sets largest imaginary parts
    447: .  -eps_smallest_imaginary - sets smallest imaginary parts
    448: .  -eps_target_magnitude   - sets eigenvalues closest to target
    449: .  -eps_target_real        - sets real parts closest to target
    450: .  -eps_target_imaginary   - sets imaginary parts closest to target
    451: -  -eps_all                - sets all eigenvalues in an interval or region

    453:    Notes:
    454:    Not all eigensolvers implemented in `EPS` account for all the possible values
    455:    of `which`. Also, some values make sense only for certain types of
    456:    problems. If SLEPc is compiled for real numbers `EPS_LARGEST_IMAGINARY`
    457:    and `EPS_SMALLEST_IMAGINARY` use the absolute value of the imaginary part
    458:    for eigenvalue selection.

    460:    The target is a scalar value provided with `EPSSetTarget()`.

    462:    The criterion `EPS_TARGET_IMAGINARY` is available only in case PETSc and
    463:    SLEPc have been built with complex scalars.

    465:    `EPS_ALL` is intended for use in combination with an interval (see
    466:    `EPSSetInterval()`), when all eigenvalues within the interval are requested,
    467:    or in the context of the `EPSCISS` solver for computing all eigenvalues in a region.

    469:    Level: intermediate

    471: .seealso: [](ch:eps), `EPSGetWhichEigenpairs()`, `EPSSetTarget()`, `EPSSetInterval()`, `EPSSetDimensions()`, `EPSSetEigenvalueComparison()`, `EPSWhich`
    472: @*/
    473: PetscErrorCode EPSSetWhichEigenpairs(EPS eps,EPSWhich which)
    474: {
    475:   PetscFunctionBegin;
    478:   switch (which) {
    479:     case EPS_LARGEST_MAGNITUDE:
    480:     case EPS_SMALLEST_MAGNITUDE:
    481:     case EPS_LARGEST_REAL:
    482:     case EPS_SMALLEST_REAL:
    483:     case EPS_LARGEST_IMAGINARY:
    484:     case EPS_SMALLEST_IMAGINARY:
    485:     case EPS_TARGET_MAGNITUDE:
    486:     case EPS_TARGET_REAL:
    487: #if defined(PETSC_USE_COMPLEX)
    488:     case EPS_TARGET_IMAGINARY:
    489: #endif
    490:     case EPS_ALL:
    491:     case EPS_WHICH_USER:
    492:       if (eps->which != which) {
    493:         eps->state = EPS_STATE_INITIAL;
    494:         eps->which = which;
    495:       }
    496:       break;
    497: #if !defined(PETSC_USE_COMPLEX)
    498:     case EPS_TARGET_IMAGINARY:
    499:       SETERRQ(PetscObjectComm((PetscObject)eps),PETSC_ERR_SUP,"EPS_TARGET_IMAGINARY can be used only with complex scalars");
    500: #endif
    501:     default:
    502:       SETERRQ(PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'which' value");
    503:   }
    504:   PetscFunctionReturn(PETSC_SUCCESS);
    505: }

    507: /*@
    508:    EPSGetWhichEigenpairs - Returns which portion of the spectrum is to be
    509:    sought.

    511:    Not Collective

    513:    Input Parameter:
    514: .  eps - the linear eigensolver context

    516:    Output Parameter:
    517: .  which - the portion of the spectrum to be sought, see `EPSWhich` for possible values

    519:    Level: intermediate

    521: .seealso: [](ch:eps), `EPSSetWhichEigenpairs()`, `EPSWhich`
    522: @*/
    523: PetscErrorCode EPSGetWhichEigenpairs(EPS eps,EPSWhich *which)
    524: {
    525:   PetscFunctionBegin;
    527:   PetscAssertPointer(which,2);
    528:   *which = eps->which;
    529:   PetscFunctionReturn(PETSC_SUCCESS);
    530: }

    532: /*@
    533:    EPSSetThreshold - Sets the threshold used in the threshold stopping test.

    535:    Logically Collective

    537:    Input Parameters:
    538: +  eps   - the linear eigensolver context
    539: .  thres - the threshold value
    540: -  rel   - whether the threshold is relative or not

    542:    Options Database Keys:
    543: +  -eps_threshold_absolute \<thres\> - sets an absolute threshold
    544: -  -eps_threshold_relative \<thres\> - sets a relative threshold

    546:    Notes:
    547:    This function internally calls `EPSSetStoppingTest()` to set a special stopping
    548:    test based on the threshold, where eigenvalues are computed in sequence until
    549:    one of the computed eigenvalues is below the threshold `thres` (in magnitude).
    550:    This is the interpretation in case of searching for largest eigenvalues in magnitude,
    551:    see `EPSSetWhichEigenpairs()`.

    553:    If the solver is configured to compute smallest magnitude eigenvalues, then the
    554:    threshold must be interpreted in the opposite direction, i.e., the computation
    555:    will stop when one of the computed values is above the threshold (in magnitude).

    557:    The threshold can also be used when computing largest/smallest real eigenvalues
    558:    (i.e, rightmost or leftmost), in which case the threshold is allowed to be
    559:    negative. The solver will stop when one of the computed eigenvalues is above
    560:    or below the threshold (considering the real part of the eigenvalue). This mode
    561:    is allowed only in problem types whose eigenvalues are always real (e.g., `EPS_HEP`).

    563:    In the case of largest magnitude eigenvalues, the threshold can be made relative
    564:    with respect to the dominant eigenvalue. Otherwise, the argument `rel` should be
    565:    `PETSC_FALSE`.

    567:    An additional use case is with target magnitude selection of eigenvalues (e.g.,
    568:    with shift-and-invert), but this must be used with caution to avoid unexpected
    569:    behavior. With an absolute threshold, the solver will assume that leftmost
    570:    eigenvalues are being computed (e.g., with `target`=0 for a problem with real
    571:    positive eigenvalues). In case of a relative threshold, a value of `thres`<1
    572:    implies that the wanted eigenvalues are the largest ones, and otherwise the
    573:    solver assumes that smallest eigenvalues are being computed.

    575:    The test against the threshold is done for converged eigenvalues, which
    576:    implies that the final number of converged eigenvalues will be at least
    577:    one more than the actual number of values below/above the threshold.

    579:    Since the number of computed eigenvalues is not known a priori, the solver
    580:    will need to reallocate the basis of vectors internally, to have enough room
    581:    to accommodate all the eigenvectors. Hence, this option must be used with
    582:    caution to avoid out-of-memory problems. The recommendation is to set the value
    583:    of `ncv` to be larger than the estimated number of eigenvalues, to minimize the
    584:    number of reallocations.

    586:    If a number of wanted eigenvalues has been set with `EPSSetDimensions()`
    587:    it is also taken into account and the solver will stop when one of the two
    588:    conditions (threshold or number of converged values) is met.

    590:    Use `EPSSetStoppingTest()` to return to the usual computation of a fixed number
    591:    of eigenvalues.

    593:    Level: advanced

    595: .seealso: [](ch:eps), `EPSGetThreshold()`, `EPSSetStoppingTest()`, `EPSSetDimensions()`, `EPSSetWhichEigenpairs()`, `EPSSetProblemType()`
    596: @*/
    597: PetscErrorCode EPSSetThreshold(EPS eps,PetscReal thres,PetscBool rel)
    598: {
    599:   PetscFunctionBegin;
    603:   if (eps->thres != thres || eps->threlative != rel) {
    604:     eps->thres = thres;
    605:     eps->threlative = rel;
    606:     eps->state = EPS_STATE_INITIAL;
    607:     PetscCall(EPSSetStoppingTest(eps,EPS_STOP_THRESHOLD));
    608:   }
    609:   PetscFunctionReturn(PETSC_SUCCESS);
    610: }

    612: /*@
    613:    EPSGetThreshold - Gets the threshold used by the threshold stopping test.

    615:    Not Collective

    617:    Input Parameter:
    618: .  eps - the linear eigensolver context

    620:    Output Parameters:
    621: +  thres - the threshold
    622: -  rel   - whether the threshold is relative or not

    624:    Level: advanced

    626: .seealso: [](ch:eps), `EPSSetThreshold()`
    627: @*/
    628: PetscErrorCode EPSGetThreshold(EPS eps,PetscReal *thres,PetscBool *rel)
    629: {
    630:   PetscFunctionBegin;
    632:   if (thres) *thres = eps->thres;
    633:   if (rel)   *rel   = eps->threlative;
    634:   PetscFunctionReturn(PETSC_SUCCESS);
    635: }

    637: /*@C
    638:    EPSSetEigenvalueComparison - Specifies the eigenvalue comparison function
    639:    when `EPSSetWhichEigenpairs()` is set to `EPS_WHICH_USER`.

    641:    Logically Collective

    643:    Input Parameters:
    644: +  eps  - the linear eigensolver context
    645: .  func - the comparison function, see `SlepcEigenvalueComparisonFn` for the calling sequence
    646: -  ctx  - a context pointer (the last parameter to the comparison function)

    648:    Level: advanced

    650: .seealso: [](ch:eps), `EPSSetWhichEigenpairs()`, `EPSWhich`
    651: @*/
    652: PetscErrorCode EPSSetEigenvalueComparison(EPS eps,SlepcEigenvalueComparisonFn *func,void *ctx)
    653: {
    654:   PetscFunctionBegin;
    656:   eps->sc->comparison    = func;
    657:   eps->sc->comparisonctx = ctx;
    658:   eps->which             = EPS_WHICH_USER;
    659:   PetscFunctionReturn(PETSC_SUCCESS);
    660: }

    662: /*@C
    663:    EPSSetArbitrarySelection - Specifies a function intended to look for
    664:    eigenvalues according to an arbitrary selection criterion. This criterion
    665:    can be based on a computation involving the current eigenvector approximation.

    667:    Logically Collective

    669:    Input Parameters:
    670: +  eps  - the linear eigensolver context
    671: .  func - the arbitrary selection function, see `SlepcArbitrarySelectionFn` for a calling sequence
    672: -  ctx  - a context pointer (the last parameter to the arbitrary selection function)

    674:    Notes:
    675:    This provides a mechanism to select eigenpairs by evaluating a user-defined
    676:    function. When a function has been provided, the default selection based on
    677:    sorting the eigenvalues is replaced by the sorting of the results of this
    678:    function (with the same sorting criterion given in `EPSSetWhichEigenpairs()`).

    680:    For instance, suppose you want to compute those eigenvectors that maximize
    681:    a certain computable expression. Then implement the computation using
    682:    the arguments `xr` and `xi`, and return the result in `rr`. Then set the standard
    683:    sorting by magnitude so that the eigenpair with largest value of `rr` is
    684:    selected.

    686:    This evaluation function is collective, that is, all processes call it and
    687:    it can use collective operations; furthermore, the computed result must
    688:    be the same in all processes.

    690:    The result of `func` is expressed as a complex number so that it is possible to
    691:    use the standard eigenvalue sorting functions, but normally only `rr` is used.
    692:    Set `ri` to zero unless it is meaningful in your application.

    694:    Level: advanced

    696: .seealso: [](ch:eps), `EPSSetWhichEigenpairs()`
    697: @*/
    698: PetscErrorCode EPSSetArbitrarySelection(EPS eps,SlepcArbitrarySelectionFn *func,void *ctx)
    699: {
    700:   PetscFunctionBegin;
    702:   eps->arbitrary    = func;
    703:   eps->arbitraryctx = ctx;
    704:   eps->state        = EPS_STATE_INITIAL;
    705:   PetscFunctionReturn(PETSC_SUCCESS);
    706: }

    708: /*@C
    709:    EPSSetConvergenceTestFunction - Sets a function to compute the error estimate
    710:    used in the convergence test.

    712:    Logically Collective

    714:    Input Parameters:
    715: +  eps     - the linear eigensolver context
    716: .  func    - convergence test function, see `EPSConvergenceTestFn` for the calling sequence
    717: .  ctx     - context for private data for the convergence routine (may be `NULL`)
    718: -  destroy - a routine for destroying the context (may be `NULL`), see `PetscCtxDestroyFn`
    719:              for the calling sequence

    721:    Notes:
    722:    When this is called with a user-defined function, then the convergence
    723:    criterion is set to `EPS_CONV_USER`, see `EPSSetConvergenceTest()`.

    725:    If the error estimate returned by the convergence test function is less than
    726:    the tolerance, then the eigenvalue is accepted as converged.

    728:    Level: advanced

    730: .seealso: [](ch:eps), `EPSSetConvergenceTest()`, `EPSSetTolerances()`
    731: @*/
    732: PetscErrorCode EPSSetConvergenceTestFunction(EPS eps,EPSConvergenceTestFn *func,void *ctx,PetscCtxDestroyFn *destroy)
    733: {
    734:   PetscFunctionBegin;
    736:   if (eps->convergeddestroy) PetscCall((*eps->convergeddestroy)(&eps->convergedctx));
    737:   eps->convergeduser    = func;
    738:   eps->convergeddestroy = destroy;
    739:   eps->convergedctx     = ctx;
    740:   if (func == EPSConvergedRelative) eps->conv = EPS_CONV_REL;
    741:   else if (func == EPSConvergedNorm) eps->conv = EPS_CONV_NORM;
    742:   else if (func == EPSConvergedAbsolute) eps->conv = EPS_CONV_ABS;
    743:   else {
    744:     eps->conv      = EPS_CONV_USER;
    745:     eps->converged = eps->convergeduser;
    746:   }
    747:   PetscFunctionReturn(PETSC_SUCCESS);
    748: }

    750: /*@
    751:    EPSSetConvergenceTest - Specifies how to compute the error estimate
    752:    used in the convergence test.

    754:    Logically Collective

    756:    Input Parameters:
    757: +  eps  - the linear eigensolver context
    758: -  conv - the type of convergence test, see `EPSConv` for possible values

    760:    Options Database Keys:
    761: +  -eps_conv_abs  - sets the absolute convergence test
    762: .  -eps_conv_rel  - sets the convergence test relative to the eigenvalue
    763: .  -eps_conv_norm - sets the convergence test relative to the matrix norms
    764: -  -eps_conv_user - selects the user-defined convergence test

    766:    Level: intermediate

    768: .seealso: [](ch:eps), `EPSGetConvergenceTest()`, `EPSSetConvergenceTestFunction()`, `EPSSetStoppingTest()`, `EPSConv`
    769: @*/
    770: PetscErrorCode EPSSetConvergenceTest(EPS eps,EPSConv conv)
    771: {
    772:   PetscFunctionBegin;
    775:   switch (conv) {
    776:     case EPS_CONV_ABS:  eps->converged = EPSConvergedAbsolute; break;
    777:     case EPS_CONV_REL:  eps->converged = EPSConvergedRelative; break;
    778:     case EPS_CONV_NORM: eps->converged = EPSConvergedNorm; break;
    779:     case EPS_CONV_USER:
    780:       PetscCheck(eps->convergeduser,PetscObjectComm((PetscObject)eps),PETSC_ERR_ORDER,"Must call EPSSetConvergenceTestFunction() first");
    781:       eps->converged = eps->convergeduser;
    782:       break;
    783:     default:
    784:       SETERRQ(PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'conv' value");
    785:   }
    786:   eps->conv = conv;
    787:   PetscFunctionReturn(PETSC_SUCCESS);
    788: }

    790: /*@
    791:    EPSGetConvergenceTest - Gets the method used to compute the error estimate
    792:    used in the convergence test.

    794:    Not Collective

    796:    Input Parameter:
    797: .  eps   - the linear eigensolver context

    799:    Output Parameter:
    800: .  conv  - the type of convergence test

    802:    Level: intermediate

    804: .seealso: [](ch:eps), `EPSSetConvergenceTest()`, `EPSConv`
    805: @*/
    806: PetscErrorCode EPSGetConvergenceTest(EPS eps,EPSConv *conv)
    807: {
    808:   PetscFunctionBegin;
    810:   PetscAssertPointer(conv,2);
    811:   *conv = eps->conv;
    812:   PetscFunctionReturn(PETSC_SUCCESS);
    813: }

    815: /*@C
    816:    EPSSetStoppingTestFunction - Sets a function to decide when to stop the outer
    817:    iteration of the eigensolver.

    819:    Logically Collective

    821:    Input Parameters:
    822: +  eps     - the linear eigensolver context
    823: .  func    - stopping test function, see `EPSStoppingTestFn` for the calling sequence
    824: .  ctx     - context for private data for the stopping routine (may be `NULL`)
    825: -  destroy - a routine for destroying the context (may be `NULL`), see `PetscCtxDestroyFn`
    826:              for the calling sequence

    828:    Note:
    829:    When implementing a function for this, normal usage is to first call the
    830:    default routine `EPSStoppingBasic()` and then set `reason` to `EPS_CONVERGED_USER`
    831:    if some user-defined conditions have been met. To let the eigensolver continue
    832:    iterating, the result must be left as `EPS_CONVERGED_ITERATING`.

    834:    Level: advanced

    836: .seealso: [](ch:eps), `EPSSetStoppingTest()`, `EPSStoppingBasic()`
    837: @*/
    838: PetscErrorCode EPSSetStoppingTestFunction(EPS eps,EPSStoppingTestFn *func,void *ctx,PetscCtxDestroyFn *destroy)
    839: {
    840:   PetscFunctionBegin;
    842:   if (eps->stoppingdestroy) PetscCall((*eps->stoppingdestroy)(&eps->stoppingctx));
    843:   eps->stoppinguser    = func;
    844:   eps->stoppingdestroy = destroy;
    845:   eps->stoppingctx     = ctx;
    846:   if (func == EPSStoppingBasic) PetscCall(EPSSetStoppingTest(eps,EPS_STOP_BASIC));
    847:   else if (func == EPSStoppingThreshold) PetscCall(EPSSetStoppingTest(eps,EPS_STOP_THRESHOLD));
    848:   else {
    849:     eps->stop     = EPS_STOP_USER;
    850:     eps->stopping = eps->stoppinguser;
    851:   }
    852:   PetscFunctionReturn(PETSC_SUCCESS);
    853: }

    855: /*@
    856:    EPSSetStoppingTest - Specifies how to decide the termination of the outer
    857:    loop of the eigensolver.

    859:    Logically Collective

    861:    Input Parameters:
    862: +  eps  - the linear eigensolver context
    863: -  stop - the type of stopping test, see `EPSStop`

    865:    Options Database Keys:
    866: +  -eps_stop_basic     - sets the default stopping test
    867: .  -eps_stop_threshold - sets the threshold stopping test
    868: -  -eps_stop_user      - selects the user-defined stopping test

    870:    Level: advanced

    872: .seealso: [](ch:eps), `EPSGetStoppingTest()`, `EPSSetStoppingTestFunction()`, `EPSSetConvergenceTest()`, `EPSStop`
    873: @*/
    874: PetscErrorCode EPSSetStoppingTest(EPS eps,EPSStop stop)
    875: {
    876:   PetscFunctionBegin;
    879:   switch (stop) {
    880:     case EPS_STOP_BASIC: eps->stopping = EPSStoppingBasic; break;
    881:     case EPS_STOP_THRESHOLD: eps->stopping = EPSStoppingThreshold; break;
    882:     case EPS_STOP_USER:
    883:       PetscCheck(eps->stoppinguser,PetscObjectComm((PetscObject)eps),PETSC_ERR_ORDER,"Must call EPSSetStoppingTestFunction() first");
    884:       eps->stopping = eps->stoppinguser;
    885:       break;
    886:     default:
    887:       SETERRQ(PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'stop' value");
    888:   }
    889:   eps->stop = stop;
    890:   PetscFunctionReturn(PETSC_SUCCESS);
    891: }

    893: /*@
    894:    EPSGetStoppingTest - Gets the method used to decide the termination of the outer
    895:    loop of the eigensolver.

    897:    Not Collective

    899:    Input Parameter:
    900: .  eps   - the linear eigensolver context

    902:    Output Parameter:
    903: .  stop  - the type of stopping test

    905:    Level: advanced

    907: .seealso: [](ch:eps), `EPSSetStoppingTest()`, `EPSStop`
    908: @*/
    909: PetscErrorCode EPSGetStoppingTest(EPS eps,EPSStop *stop)
    910: {
    911:   PetscFunctionBegin;
    913:   PetscAssertPointer(stop,2);
    914:   *stop = eps->stop;
    915:   PetscFunctionReturn(PETSC_SUCCESS);
    916: }

    918: /*@
    919:    EPSSetProblemType - Specifies the type of the eigenvalue problem.

    921:    Logically Collective

    923:    Input Parameters:
    924: +  eps  - the linear eigensolver context
    925: -  type - a known type of eigenvalue problem

    927:    Options Database Keys:
    928: +  -eps_hermitian             - Hermitian eigenvalue problem
    929: .  -eps_gen_hermitian         - generalized Hermitian eigenvalue problem
    930: .  -eps_non_hermitian         - non-Hermitian eigenvalue problem
    931: .  -eps_gen_non_hermitian     - generalized non-Hermitian eigenvalue problem
    932: .  -eps_pos_gen_non_hermitian - generalized non-Hermitian eigenvalue problem
    933:                                 with positive semi-definite $B$
    934: .  -eps_gen_indefinite        - generalized Hermitian-indefinite eigenvalue problem
    935: .  -eps_bse                   - structured Bethe-Salpeter eigenvalue problem
    936: -  -eps_hamiltonian           - structured Hamiltonian eigenvalue problem

    938:    Notes:
    939:    This function must be used to instruct SLEPc to exploit symmetry or other
    940:    kind of structure. If no
    941:    problem type is specified, by default a non-Hermitian problem is assumed
    942:    (either standard or generalized). If the user knows that the problem is
    943:    Hermitian (i.e., $A=A^*$) or generalized Hermitian (i.e., $A=A^*$, $B=B^*$,
    944:    and $B$ positive definite) then it is recommended to set the problem type so
    945:    that the eigensolver can exploit these properties.

    947:    If the user does not call this function, the solver will use a reasonable
    948:    guess.

    950:    For structured problem types such as `EPS_BSE`, the matrices passed in via
    951:    `EPSSetOperators()` must have been created with the corresponding helper
    952:    function, i.e., `MatCreateBSE()`.

    954:    Level: intermediate

    956: .seealso: [](ch:eps), `EPSSetOperators()`, `EPSSetType()`, `EPSGetProblemType()`, `EPSProblemType`
    957: @*/
    958: PetscErrorCode EPSSetProblemType(EPS eps,EPSProblemType type)
    959: {
    960:   PetscFunctionBegin;
    963:   if (type == eps->problem_type) PetscFunctionReturn(PETSC_SUCCESS);
    964:   switch (type) {
    965:     case EPS_HEP:
    966:       eps->isgeneralized = PETSC_FALSE;
    967:       eps->ishermitian = PETSC_TRUE;
    968:       eps->ispositive = PETSC_FALSE;
    969:       eps->isstructured = PETSC_FALSE;
    970:       break;
    971:     case EPS_NHEP:
    972:       eps->isgeneralized = PETSC_FALSE;
    973:       eps->ishermitian = PETSC_FALSE;
    974:       eps->ispositive = PETSC_FALSE;
    975:       eps->isstructured = PETSC_FALSE;
    976:       break;
    977:     case EPS_GHEP:
    978:       eps->isgeneralized = PETSC_TRUE;
    979:       eps->ishermitian = PETSC_TRUE;
    980:       eps->ispositive = PETSC_TRUE;
    981:       eps->isstructured = PETSC_FALSE;
    982:       break;
    983:     case EPS_GNHEP:
    984:       eps->isgeneralized = PETSC_TRUE;
    985:       eps->ishermitian = PETSC_FALSE;
    986:       eps->ispositive = PETSC_FALSE;
    987:       eps->isstructured = PETSC_FALSE;
    988:       break;
    989:     case EPS_PGNHEP:
    990:       eps->isgeneralized = PETSC_TRUE;
    991:       eps->ishermitian = PETSC_FALSE;
    992:       eps->ispositive = PETSC_TRUE;
    993:       eps->isstructured = PETSC_FALSE;
    994:       break;
    995:     case EPS_GHIEP:
    996:       eps->isgeneralized = PETSC_TRUE;
    997:       eps->ishermitian = PETSC_TRUE;
    998:       eps->ispositive = PETSC_FALSE;
    999:       eps->isstructured = PETSC_FALSE;
    1000:       break;
    1001:     case EPS_BSE:
    1002:       eps->isgeneralized = PETSC_FALSE;
    1003:       eps->ishermitian = PETSC_FALSE;
    1004:       eps->ispositive = PETSC_FALSE;
    1005:       eps->isstructured = PETSC_TRUE;
    1006:       break;
    1007:     case EPS_HAMILT:
    1008:       eps->isgeneralized = PETSC_FALSE;
    1009:       eps->ishermitian = PETSC_FALSE;
    1010:       eps->ispositive = PETSC_FALSE;
    1011:       eps->isstructured = PETSC_TRUE;
    1012:       break;
    1013:     default:
    1014:       SETERRQ(PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_WRONG,"Unknown eigenvalue problem type");
    1015:   }
    1016:   eps->problem_type = type;
    1017:   eps->state = EPS_STATE_INITIAL;
    1018:   PetscFunctionReturn(PETSC_SUCCESS);
    1019: }

    1021: /*@
    1022:    EPSGetProblemType - Gets the problem type from the `EPS` object.

    1024:    Not Collective

    1026:    Input Parameter:
    1027: .  eps - the linear eigensolver context

    1029:    Output Parameter:
    1030: .  type - the problem type

    1032:    Level: intermediate

    1034: .seealso: [](ch:eps), `EPSSetProblemType()`, `EPSProblemType`
    1035: @*/
    1036: PetscErrorCode EPSGetProblemType(EPS eps,EPSProblemType *type)
    1037: {
    1038:   PetscFunctionBegin;
    1040:   PetscAssertPointer(type,2);
    1041:   *type = eps->problem_type;
    1042:   PetscFunctionReturn(PETSC_SUCCESS);
    1043: }

    1045: /*@
    1046:    EPSSetExtraction - Specifies the type of extraction technique to be employed
    1047:    by the eigensolver.

    1049:    Logically Collective

    1051:    Input Parameters:
    1052: +  eps  - the linear eigensolver context
    1053: -  extr - a known type of extraction

    1055:    Options Database Keys:
    1056: +  -eps_ritz              - Rayleigh-Ritz extraction
    1057: .  -eps_harmonic          - harmonic Ritz extraction
    1058: .  -eps_harmonic_relative - harmonic Ritz extraction relative to the eigenvalue
    1059: .  -eps_harmonic_right    - harmonic Ritz extraction for rightmost eigenvalues
    1060: .  -eps_harmonic_largest  - harmonic Ritz extraction for largest magnitude (without target)
    1061: .  -eps_refined           - refined Ritz extraction
    1062: -  -eps_refined_harmonic  - refined harmonic Ritz extraction

    1064:    Notes:
    1065:    Not all eigensolvers support all types of extraction.

    1067:    By default, a standard Rayleigh-Ritz extraction is used. Other extractions
    1068:    may be useful when computing interior eigenvalues.

    1070:    Harmonic-type extractions are used in combination with a target, see `EPSSetTarget()`.

    1072:    Level: advanced

    1074: .seealso: [](ch:eps), [](#sec:harmonic), `EPSSetTarget()`, `EPSGetExtraction()`, `EPSExtraction`
    1075: @*/
    1076: PetscErrorCode EPSSetExtraction(EPS eps,EPSExtraction extr)
    1077: {
    1078:   PetscFunctionBegin;
    1081:   if (eps->extraction != extr) {
    1082:     eps->state      = EPS_STATE_INITIAL;
    1083:     eps->extraction = extr;
    1084:   }
    1085:   PetscFunctionReturn(PETSC_SUCCESS);
    1086: }

    1088: /*@
    1089:    EPSGetExtraction - Gets the extraction type used by the `EPS` object.

    1091:    Not Collective

    1093:    Input Parameter:
    1094: .  eps - the linear eigensolver context

    1096:    Output Parameter:
    1097: .  extr - name of extraction type

    1099:    Level: advanced

    1101: .seealso: [](ch:eps), `EPSSetExtraction()`, `EPSExtraction`
    1102: @*/
    1103: PetscErrorCode EPSGetExtraction(EPS eps,EPSExtraction *extr)
    1104: {
    1105:   PetscFunctionBegin;
    1107:   PetscAssertPointer(extr,2);
    1108:   *extr = eps->extraction;
    1109:   PetscFunctionReturn(PETSC_SUCCESS);
    1110: }

    1112: /*@
    1113:    EPSSetBalance - Specifies the balancing technique to be employed by the
    1114:    eigensolver, and some parameters associated to it.

    1116:    Logically Collective

    1118:    Input Parameters:
    1119: +  eps    - the linear eigensolver context
    1120: .  bal    - the balancing method, see `EPSBalance` for possible values
    1121: .  its    - number of iterations of the balancing algorithm
    1122: -  cutoff - cutoff value

    1124:    Options Database Keys:
    1125: +  -eps_balance \<bal\>           - the balancing method, one of `none`, `oneside`, `twoside`, or `user`
    1126: .  -eps_balance_its \<its\>       - number of iterations
    1127: -  -eps_balance_cutoff \<cutoff\> - cutoff value

    1129:    Notes:
    1130:    When balancing is enabled, the solver works implicitly with matrix $DAD^{-1}$,
    1131:    where $D$ is an appropriate diagonal matrix. This improves the accuracy of
    1132:    the computed results in some cases, see [](sec:balancing).

    1134:    Balancing makes sense only for non-Hermitian problems when the required
    1135:    precision is high (i.e., a small tolerance such as `1e-14`).

    1137:    By default, balancing is disabled. The two-sided method is much more
    1138:    effective than the one-sided counterpart, but it requires the system
    1139:    matrices to have the `MatMultTranspose()` operation defined. The methods
    1140:    are described in {cite:p}`Che00`.

    1142:    The parameter `its` is the number of iterations performed by the method. The
    1143:    `cutoff` value is used only in the two-side variant. Use `PETSC_DETERMINE` to assign
    1144:    a reasonably good value, or `PETSC_CURRENT` to leave the value unchanged.

    1146:    User-defined balancing is allowed provided that the corresponding matrix
    1147:    is set via `STSetBalanceMatrix()`.

    1149:    Level: intermediate

    1151: .seealso: [](ch:eps), [](sec:balancing), `EPSGetBalance()`, `EPSBalance`, `STSetBalanceMatrix()`
    1152: @*/
    1153: PetscErrorCode EPSSetBalance(EPS eps,EPSBalance bal,PetscInt its,PetscReal cutoff)
    1154: {
    1155:   PetscFunctionBegin;
    1160:   switch (bal) {
    1161:     case EPS_BALANCE_NONE:
    1162:     case EPS_BALANCE_ONESIDE:
    1163:     case EPS_BALANCE_TWOSIDE:
    1164:     case EPS_BALANCE_USER:
    1165:       if (eps->balance != bal) {
    1166:         eps->state = EPS_STATE_INITIAL;
    1167:         eps->balance = bal;
    1168:       }
    1169:       break;
    1170:     default:
    1171:       SETERRQ(PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Invalid value of argument 'bal'");
    1172:   }
    1173:   if (its==PETSC_DETERMINE) eps->balance_its = 5;
    1174:   else if (its!=PETSC_CURRENT) {
    1175:     PetscCheck(its>0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of its. Must be > 0");
    1176:     eps->balance_its = its;
    1177:   }
    1178:   if (cutoff==(PetscReal)PETSC_DETERMINE) eps->balance_cutoff = 1e-8;
    1179:   else if (cutoff!=(PetscReal)PETSC_CURRENT) {
    1180:     PetscCheck(cutoff>0.0,PetscObjectComm((PetscObject)eps),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of cutoff. Must be > 0");
    1181:     eps->balance_cutoff = cutoff;
    1182:   }
    1183:   PetscFunctionReturn(PETSC_SUCCESS);
    1184: }

    1186: /*@
    1187:    EPSGetBalance - Gets the balancing type used by the `EPS` object, and the
    1188:    associated parameters.

    1190:    Not Collective

    1192:    Input Parameter:
    1193: .  eps - the linear eigensolver context

    1195:    Output Parameters:
    1196: +  bal    - the balancing method
    1197: .  its    - number of iterations of the balancing algorithm
    1198: -  cutoff - cutoff value

    1200:    Level: intermediate

    1202:    Note:
    1203:    The user can specify `NULL` for any parameter that is not needed.

    1205: .seealso: [](ch:eps), `EPSSetBalance()`, `EPSBalance`
    1206: @*/
    1207: PetscErrorCode EPSGetBalance(EPS eps,EPSBalance *bal,PetscInt *its,PetscReal *cutoff)
    1208: {
    1209:   PetscFunctionBegin;
    1211:   if (bal)    *bal = eps->balance;
    1212:   if (its)    *its = eps->balance_its;
    1213:   if (cutoff) *cutoff = eps->balance_cutoff;
    1214:   PetscFunctionReturn(PETSC_SUCCESS);
    1215: }

    1217: /*@
    1218:    EPSSetTwoSided - Sets the solver to use a two-sided variant so that left
    1219:    eigenvectors are also computed.

    1221:    Logically Collective

    1223:    Input Parameters:
    1224: +  eps      - the linear eigensolver context
    1225: -  twosided - whether the two-sided variant is to be used or not

    1227:    Options Database Key:
    1228: .  -eps_two_sided - toggles the twosided flag

    1230:    Notes:
    1231:    If the user sets `twosided`=`PETSC_TRUE` then the solver uses a variant of
    1232:    the algorithm that computes both right and left eigenvectors. This is
    1233:    usually much more costly. This option is not available in all solvers,
    1234:    see table [](#tab:support).

    1236:    When using two-sided solvers, the problem matrices must have both the
    1237:    `MATOP_MULT` and `MATOP_MULT_TRANSPOSE` operations defined.

    1239:    Level: advanced

    1241: .seealso: [](ch:eps), `EPSGetTwoSided()`, `EPSGetLeftEigenvector()`
    1242: @*/
    1243: PetscErrorCode EPSSetTwoSided(EPS eps,PetscBool twosided)
    1244: {
    1245:   PetscFunctionBegin;
    1248:   if (twosided!=eps->twosided) {
    1249:     eps->twosided = twosided;
    1250:     eps->state    = EPS_STATE_INITIAL;
    1251:   }
    1252:   PetscFunctionReturn(PETSC_SUCCESS);
    1253: }

    1255: /*@
    1256:    EPSGetTwoSided - Returns the flag indicating whether a two-sided variant
    1257:    of the algorithm is being used or not.

    1259:    Not Collective

    1261:    Input Parameter:
    1262: .  eps - the linear eigensolver context

    1264:    Output Parameter:
    1265: .  twosided - the returned flag

    1267:    Level: advanced

    1269: .seealso: [](ch:eps), `EPSSetTwoSided()`
    1270: @*/
    1271: PetscErrorCode EPSGetTwoSided(EPS eps,PetscBool *twosided)
    1272: {
    1273:   PetscFunctionBegin;
    1275:   PetscAssertPointer(twosided,2);
    1276:   *twosided = eps->twosided;
    1277:   PetscFunctionReturn(PETSC_SUCCESS);
    1278: }

    1280: /*@
    1281:    EPSSetTrueResidual - Specifies if the solver must compute the true residual
    1282:    explicitly or not.

    1284:    Logically Collective

    1286:    Input Parameters:
    1287: +  eps     - the linear eigensolver context
    1288: -  trueres - whether true residuals are required or not

    1290:    Options Database Key:
    1291: .  -eps_true_residual - toggles the true residual

    1293:    Notes:
    1294:    If the user sets `trueres`=`PETSC_TRUE` then the solver explicitly computes
    1295:    the true residual for each eigenpair approximation, and uses it for
    1296:    convergence testing. Computing the residual is usually an expensive
    1297:    operation. Some solvers (e.g., Krylov solvers) can avoid this computation
    1298:    by using a cheap estimate of the residual norm, but this may sometimes
    1299:    give inaccurate results (especially if a spectral transform is being
    1300:    used). On the contrary, preconditioned eigensolvers (e.g., Davidson solvers)
    1301:    do rely on computing the true residual, so this option is irrelevant for them.

    1303:    Level: advanced

    1305: .seealso: [](ch:eps), `EPSGetTrueResidual()`
    1306: @*/
    1307: PetscErrorCode EPSSetTrueResidual(EPS eps,PetscBool trueres)
    1308: {
    1309:   PetscFunctionBegin;
    1312:   eps->trueres = trueres;
    1313:   PetscFunctionReturn(PETSC_SUCCESS);
    1314: }

    1316: /*@
    1317:    EPSGetTrueResidual - Returns the flag indicating whether true
    1318:    residuals must be computed explicitly or not.

    1320:    Not Collective

    1322:    Input Parameter:
    1323: .  eps - the linear eigensolver context

    1325:    Output Parameter:
    1326: .  trueres - the returned flag

    1328:    Level: advanced

    1330: .seealso: [](ch:eps), `EPSSetTrueResidual()`
    1331: @*/
    1332: PetscErrorCode EPSGetTrueResidual(EPS eps,PetscBool *trueres)
    1333: {
    1334:   PetscFunctionBegin;
    1336:   PetscAssertPointer(trueres,2);
    1337:   *trueres = eps->trueres;
    1338:   PetscFunctionReturn(PETSC_SUCCESS);
    1339: }

    1341: /*@
    1342:    EPSSetTrackAll - Specifies if the solver must compute the residual norm of all
    1343:    approximate eigenpairs or not.

    1345:    Logically Collective

    1347:    Input Parameters:
    1348: +  eps      - the linear eigensolver context
    1349: -  trackall - whether to compute all residuals or not

    1351:    Notes:
    1352:    If the user sets `trackall`=`PETSC_TRUE` then the solver computes (or estimates)
    1353:    the residual norm for each eigenpair approximation. Computing the residual is
    1354:    usually an expensive operation and solvers commonly compute only the residual
    1355:    associated to the first unconverged eigenpair.

    1357:    The option `-eps_monitor_all` automatically activates this option.

    1359:    Level: developer

    1361: .seealso: [](ch:eps), `EPSGetTrackAll()`
    1362: @*/
    1363: PetscErrorCode EPSSetTrackAll(EPS eps,PetscBool trackall)
    1364: {
    1365:   PetscFunctionBegin;
    1368:   eps->trackall = trackall;
    1369:   PetscFunctionReturn(PETSC_SUCCESS);
    1370: }

    1372: /*@
    1373:    EPSGetTrackAll - Returns the flag indicating whether all residual norms must
    1374:    be computed or not.

    1376:    Not Collective

    1378:    Input Parameter:
    1379: .  eps - the linear eigensolver context

    1381:    Output Parameter:
    1382: .  trackall - the returned flag

    1384:    Level: developer

    1386: .seealso: [](ch:eps), `EPSSetTrackAll()`
    1387: @*/
    1388: PetscErrorCode EPSGetTrackAll(EPS eps,PetscBool *trackall)
    1389: {
    1390:   PetscFunctionBegin;
    1392:   PetscAssertPointer(trackall,2);
    1393:   *trackall = eps->trackall;
    1394:   PetscFunctionReturn(PETSC_SUCCESS);
    1395: }

    1397: /*@
    1398:    EPSSetPurify - Disable eigenvector purification (which is enabled by default).

    1400:    Logically Collective

    1402:    Input Parameters:
    1403: +  eps    - the linear eigensolver context
    1404: -  purify - whether purification is done or not, use `PETSC_FALSE` to disable it

    1406:    Options Database Key:
    1407: .  -eps_purify - toggles the purification flag

    1409:    Notes:
    1410:    By default, eigenvectors of generalized symmetric eigenproblems are purified
    1411:    in order to purge directions in the nullspace of matrix $B$. If the user knows
    1412:    that $B$ is non-singular, then purification can be safely deactivated and some
    1413:    computational cost is avoided (this is particularly important in interval computations).

    1415:    More details are given in section [](#sec:purif).

    1417:    Level: intermediate

    1419: .seealso: [](ch:eps), [](#sec:purif), `EPSGetPurify()`, `EPSSetInterval()`
    1420: @*/
    1421: PetscErrorCode EPSSetPurify(EPS eps,PetscBool purify)
    1422: {
    1423:   PetscFunctionBegin;
    1426:   if (purify!=eps->purify) {
    1427:     eps->purify = purify;
    1428:     eps->state  = EPS_STATE_INITIAL;
    1429:   }
    1430:   PetscFunctionReturn(PETSC_SUCCESS);
    1431: }

    1433: /*@
    1434:    EPSGetPurify - Returns the flag indicating whether purification is activated
    1435:    or not.

    1437:    Not Collective

    1439:    Input Parameter:
    1440: .  eps - the linear eigensolver context

    1442:    Output Parameter:
    1443: .  purify - the returned flag

    1445:    Level: intermediate

    1447: .seealso: [](ch:eps), `EPSSetPurify()`
    1448: @*/
    1449: PetscErrorCode EPSGetPurify(EPS eps,PetscBool *purify)
    1450: {
    1451:   PetscFunctionBegin;
    1453:   PetscAssertPointer(purify,2);
    1454:   *purify = eps->purify;
    1455:   PetscFunctionReturn(PETSC_SUCCESS);
    1456: }

    1458: /*@
    1459:    EPSSetOptionsPrefix - Sets the prefix used for searching for all
    1460:    `EPS` options in the database.

    1462:    Logically Collective

    1464:    Input Parameters:
    1465: +  eps    - the linear eigensolver context
    1466: -  prefix - the prefix string to prepend to all `EPS` option requests

    1468:    Notes:
    1469:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    1470:    The first character of all runtime options is AUTOMATICALLY the
    1471:    hyphen.

    1473:    For example, to distinguish between the runtime options for two
    1474:    different `EPS` contexts, one could call
    1475: .vb
    1476:    EPSSetOptionsPrefix(eps1,"eig1_")
    1477:    EPSSetOptionsPrefix(eps2,"eig2_")
    1478: .ve

    1480:    Level: advanced

    1482: .seealso: [](ch:eps), `EPSAppendOptionsPrefix()`, `EPSGetOptionsPrefix()`
    1483: @*/
    1484: PetscErrorCode EPSSetOptionsPrefix(EPS eps,const char prefix[])
    1485: {
    1486:   PetscFunctionBegin;
    1488:   if (!eps->st) PetscCall(EPSGetST(eps,&eps->st));
    1489:   PetscCall(STSetOptionsPrefix(eps->st,prefix));
    1490:   if (!eps->V) PetscCall(EPSGetBV(eps,&eps->V));
    1491:   PetscCall(BVSetOptionsPrefix(eps->V,prefix));
    1492:   if (!eps->ds) PetscCall(EPSGetDS(eps,&eps->ds));
    1493:   PetscCall(DSSetOptionsPrefix(eps->ds,prefix));
    1494:   if (!eps->rg) PetscCall(EPSGetRG(eps,&eps->rg));
    1495:   PetscCall(RGSetOptionsPrefix(eps->rg,prefix));
    1496:   PetscCall(PetscObjectSetOptionsPrefix((PetscObject)eps,prefix));
    1497:   PetscFunctionReturn(PETSC_SUCCESS);
    1498: }

    1500: /*@
    1501:    EPSAppendOptionsPrefix - Appends to the prefix used for searching for all
    1502:    `EPS` options in the database.

    1504:    Logically Collective

    1506:    Input Parameters:
    1507: +  eps    - the linear eigensolver context
    1508: -  prefix - the prefix string to prepend to all `EPS` option requests

    1510:    Notes:
    1511:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    1512:    The first character of all runtime options is AUTOMATICALLY the hyphen.

    1514:    Level: advanced

    1516: .seealso: [](ch:eps), `EPSSetOptionsPrefix()`, `EPSGetOptionsPrefix()`
    1517: @*/
    1518: PetscErrorCode EPSAppendOptionsPrefix(EPS eps,const char prefix[])
    1519: {
    1520:   PetscFunctionBegin;
    1522:   if (!eps->st) PetscCall(EPSGetST(eps,&eps->st));
    1523:   PetscCall(STAppendOptionsPrefix(eps->st,prefix));
    1524:   if (!eps->V) PetscCall(EPSGetBV(eps,&eps->V));
    1525:   PetscCall(BVAppendOptionsPrefix(eps->V,prefix));
    1526:   if (!eps->ds) PetscCall(EPSGetDS(eps,&eps->ds));
    1527:   PetscCall(DSAppendOptionsPrefix(eps->ds,prefix));
    1528:   if (!eps->rg) PetscCall(EPSGetRG(eps,&eps->rg));
    1529:   PetscCall(RGAppendOptionsPrefix(eps->rg,prefix));
    1530:   PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)eps,prefix));
    1531:   PetscFunctionReturn(PETSC_SUCCESS);
    1532: }

    1534: /*@
    1535:    EPSGetOptionsPrefix - Gets the prefix used for searching for all
    1536:    `EPS` options in the database.

    1538:    Not Collective

    1540:    Input Parameter:
    1541: .  eps - the linear eigensolver context

    1543:    Output Parameter:
    1544: .  prefix - pointer to the prefix string used is returned

    1546:    Level: advanced

    1548: .seealso: [](ch:eps), `EPSSetOptionsPrefix()`, `EPSAppendOptionsPrefix()`
    1549: @*/
    1550: PetscErrorCode EPSGetOptionsPrefix(EPS eps,const char *prefix[])
    1551: {
    1552:   PetscFunctionBegin;
    1554:   PetscAssertPointer(prefix,2);
    1555:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)eps,prefix));
    1556:   PetscFunctionReturn(PETSC_SUCCESS);
    1557: }