Date: 2026-01-20T11:35:09+00:00

Actual source code: pepopts.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:    PEP routines related to options that can be set via the command-line
     12:    or procedurally
     13: */

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

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

     22:    Collective

     24:    Input Parameters:
     25: +  pep      - the polynomial 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:pep), `PEPMonitorSet()`, `PEPSetTrackAll()`
     34: @*/
     35: PetscErrorCode PEPMonitorSetFromOptions(PEP pep,const char opt[],const char name[],void *ctx,PetscBool trackall)
     36: {
     37:   PetscErrorCode       (*mfunc)(PEP,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)pep),((PetscObject)pep)->options,((PetscObject)pep)->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(PEPMonitorList,key,&mfunc));
     54:   PetscCheck(mfunc,PetscObjectComm((PetscObject)pep),PETSC_ERR_SUP,"Specified viewer and format not supported");
     55:   PetscCall(PetscFunctionListFind(PEPMonitorCreateList,key,&cfunc));
     56:   PetscCall(PetscFunctionListFind(PEPMonitorDestroyList,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(PEPMonitorSet(pep,mfunc,vf,(PetscCtxDestroyFn*)dfunc));
     63:   if (trackall) PetscCall(PEPSetTrackAll(pep,PETSC_TRUE));
     64:   PetscFunctionReturn(PETSC_SUCCESS);
     65: }

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

     72:    Collective

     74:    Input Parameter:
     75: .  pep - the polynomial eigensolver context

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

     80:    Level: beginner

     82: .seealso: [](ch:pep), `PEPSetOptionsPrefix()`
     83: @*/
     84: PetscErrorCode PEPSetFromOptions(PEP pep)
     85: {
     86:   char            type[256];
     87:   PetscBool       set,flg,flg1,flg2,flg3,flg4,flg5;
     88:   PetscReal       r,t,array[2]={0,0};
     89:   PetscScalar     s;
     90:   PetscInt        i,j,k;
     91:   PEPScale        scale;
     92:   PEPRefine       refine;
     93:   PEPRefineScheme scheme;

     95:   PetscFunctionBegin;
     97:   PetscCall(PEPRegisterAll());
     98:   PetscObjectOptionsBegin((PetscObject)pep);
     99:     PetscCall(PetscOptionsFList("-pep_type","Polynomial eigensolver method","PEPSetType",PEPList,(char*)(((PetscObject)pep)->type_name?((PetscObject)pep)->type_name:PEPTOAR),type,sizeof(type),&flg));
    100:     if (flg) PetscCall(PEPSetType(pep,type));
    101:     else if (!((PetscObject)pep)->type_name) PetscCall(PEPSetType(pep,PEPTOAR));

    103:     PetscCall(PetscOptionsBoolGroupBegin("-pep_general","General polynomial eigenvalue problem","PEPSetProblemType",&flg));
    104:     if (flg) PetscCall(PEPSetProblemType(pep,PEP_GENERAL));
    105:     PetscCall(PetscOptionsBoolGroup("-pep_hermitian","Hermitian polynomial eigenvalue problem","PEPSetProblemType",&flg));
    106:     if (flg) PetscCall(PEPSetProblemType(pep,PEP_HERMITIAN));
    107:     PetscCall(PetscOptionsBoolGroup("-pep_hyperbolic","Hyperbolic polynomial eigenvalue problem","PEPSetProblemType",&flg));
    108:     if (flg) PetscCall(PEPSetProblemType(pep,PEP_HYPERBOLIC));
    109:     PetscCall(PetscOptionsBoolGroupEnd("-pep_gyroscopic","Gyroscopic polynomial eigenvalue problem","PEPSetProblemType",&flg));
    110:     if (flg) PetscCall(PEPSetProblemType(pep,PEP_GYROSCOPIC));

    112:     scale = pep->scale;
    113:     PetscCall(PetscOptionsEnum("-pep_scale","Scaling strategy","PEPSetScale",PEPScaleTypes,(PetscEnum)scale,(PetscEnum*)&scale,&flg1));
    114:     r = pep->sfactor;
    115:     PetscCall(PetscOptionsReal("-pep_scale_factor","Scale factor","PEPSetScale",pep->sfactor,&r,&flg2));
    116:     if (!flg2 && r==1.0) r = PETSC_DETERMINE;
    117:     j = pep->sits;
    118:     PetscCall(PetscOptionsInt("-pep_scale_its","Number of iterations in diagonal scaling","PEPSetScale",pep->sits,&j,&flg3));
    119:     t = pep->slambda;
    120:     PetscCall(PetscOptionsReal("-pep_scale_lambda","Estimate of eigenvalue (modulus) for diagonal scaling","PEPSetScale",pep->slambda,&t,&flg4));
    121:     if (flg1 || flg2 || flg3 || flg4) PetscCall(PEPSetScale(pep,scale,r,NULL,NULL,j,t));

    123:     PetscCall(PetscOptionsEnum("-pep_extract","Extraction method","PEPSetExtract",PEPExtractTypes,(PetscEnum)pep->extract,(PetscEnum*)&pep->extract,NULL));

    125:     refine = pep->refine;
    126:     PetscCall(PetscOptionsEnum("-pep_refine","Iterative refinement method","PEPSetRefine",PEPRefineTypes,(PetscEnum)refine,(PetscEnum*)&refine,&flg1));
    127:     i = pep->npart;
    128:     PetscCall(PetscOptionsInt("-pep_refine_partitions","Number of partitions of the communicator for iterative refinement","PEPSetRefine",pep->npart,&i,&flg2));
    129:     r = pep->rtol;
    130:     PetscCall(PetscOptionsReal("-pep_refine_tol","Tolerance for iterative refinement","PEPSetRefine",pep->rtol==(PetscReal)PETSC_DETERMINE?SLEPC_DEFAULT_TOL/1000:pep->rtol,&r,&flg3));
    131:     j = pep->rits;
    132:     PetscCall(PetscOptionsInt("-pep_refine_its","Maximum number of iterations for iterative refinement","PEPSetRefine",pep->rits,&j,&flg4));
    133:     scheme = pep->scheme;
    134:     PetscCall(PetscOptionsEnum("-pep_refine_scheme","Scheme used for linear systems within iterative refinement","PEPSetRefine",PEPRefineSchemes,(PetscEnum)scheme,(PetscEnum*)&scheme,&flg5));
    135:     if (flg1 || flg2 || flg3 || flg4 || flg5) PetscCall(PEPSetRefine(pep,refine,i,r,j,scheme));

    137:     i = pep->max_it;
    138:     PetscCall(PetscOptionsInt("-pep_max_it","Maximum number of iterations","PEPSetTolerances",pep->max_it,&i,&flg1));
    139:     r = pep->tol;
    140:     PetscCall(PetscOptionsReal("-pep_tol","Tolerance","PEPSetTolerances",SlepcDefaultTol(pep->tol),&r,&flg2));
    141:     if (flg1 || flg2) PetscCall(PEPSetTolerances(pep,r,i));

    143:     PetscCall(PetscOptionsBoolGroupBegin("-pep_conv_rel","Relative error convergence test","PEPSetConvergenceTest",&flg));
    144:     if (flg) PetscCall(PEPSetConvergenceTest(pep,PEP_CONV_REL));
    145:     PetscCall(PetscOptionsBoolGroup("-pep_conv_norm","Convergence test relative to the matrix norms","PEPSetConvergenceTest",&flg));
    146:     if (flg) PetscCall(PEPSetConvergenceTest(pep,PEP_CONV_NORM));
    147:     PetscCall(PetscOptionsBoolGroup("-pep_conv_abs","Absolute error convergence test","PEPSetConvergenceTest",&flg));
    148:     if (flg) PetscCall(PEPSetConvergenceTest(pep,PEP_CONV_ABS));
    149:     PetscCall(PetscOptionsBoolGroupEnd("-pep_conv_user","User-defined convergence test","PEPSetConvergenceTest",&flg));
    150:     if (flg) PetscCall(PEPSetConvergenceTest(pep,PEP_CONV_USER));

    152:     PetscCall(PetscOptionsBoolGroupBegin("-pep_stop_basic","Stop iteration if all eigenvalues converged or max_it reached","PEPSetStoppingTest",&flg));
    153:     if (flg) PetscCall(PEPSetStoppingTest(pep,PEP_STOP_BASIC));
    154:     PetscCall(PetscOptionsBoolGroupEnd("-pep_stop_user","User-defined stopping test","PEPSetStoppingTest",&flg));
    155:     if (flg) PetscCall(PEPSetStoppingTest(pep,PEP_STOP_USER));

    157:     i = pep->nev;
    158:     PetscCall(PetscOptionsInt("-pep_nev","Number of eigenvalues to compute","PEPSetDimensions",pep->nev,&i,&flg1));
    159:     j = pep->ncv;
    160:     PetscCall(PetscOptionsInt("-pep_ncv","Number of basis vectors","PEPSetDimensions",pep->ncv,&j,&flg2));
    161:     k = pep->mpd;
    162:     PetscCall(PetscOptionsInt("-pep_mpd","Maximum dimension of projected problem","PEPSetDimensions",pep->mpd,&k,&flg3));
    163:     if (flg1 || flg2 || flg3) PetscCall(PEPSetDimensions(pep,i,j,k));

    165:     PetscCall(PetscOptionsEnum("-pep_basis","Polynomial basis","PEPSetBasis",PEPBasisTypes,(PetscEnum)pep->basis,(PetscEnum*)&pep->basis,NULL));

    167:     PetscCall(PetscOptionsBoolGroupBegin("-pep_largest_magnitude","Compute largest eigenvalues in magnitude","PEPSetWhichEigenpairs",&flg));
    168:     if (flg) PetscCall(PEPSetWhichEigenpairs(pep,PEP_LARGEST_MAGNITUDE));
    169:     PetscCall(PetscOptionsBoolGroup("-pep_smallest_magnitude","Compute smallest eigenvalues in magnitude","PEPSetWhichEigenpairs",&flg));
    170:     if (flg) PetscCall(PEPSetWhichEigenpairs(pep,PEP_SMALLEST_MAGNITUDE));
    171:     PetscCall(PetscOptionsBoolGroup("-pep_largest_real","Compute eigenvalues with largest real parts","PEPSetWhichEigenpairs",&flg));
    172:     if (flg) PetscCall(PEPSetWhichEigenpairs(pep,PEP_LARGEST_REAL));
    173:     PetscCall(PetscOptionsBoolGroup("-pep_smallest_real","Compute eigenvalues with smallest real parts","PEPSetWhichEigenpairs",&flg));
    174:     if (flg) PetscCall(PEPSetWhichEigenpairs(pep,PEP_SMALLEST_REAL));
    175:     PetscCall(PetscOptionsBoolGroup("-pep_largest_imaginary","Compute eigenvalues with largest imaginary parts","PEPSetWhichEigenpairs",&flg));
    176:     if (flg) PetscCall(PEPSetWhichEigenpairs(pep,PEP_LARGEST_IMAGINARY));
    177:     PetscCall(PetscOptionsBoolGroup("-pep_smallest_imaginary","Compute eigenvalues with smallest imaginary parts","PEPSetWhichEigenpairs",&flg));
    178:     if (flg) PetscCall(PEPSetWhichEigenpairs(pep,PEP_SMALLEST_IMAGINARY));
    179:     PetscCall(PetscOptionsBoolGroup("-pep_target_magnitude","Compute eigenvalues closest to target","PEPSetWhichEigenpairs",&flg));
    180:     if (flg) PetscCall(PEPSetWhichEigenpairs(pep,PEP_TARGET_MAGNITUDE));
    181:     PetscCall(PetscOptionsBoolGroup("-pep_target_real","Compute eigenvalues with real parts closest to target","PEPSetWhichEigenpairs",&flg));
    182:     if (flg) PetscCall(PEPSetWhichEigenpairs(pep,PEP_TARGET_REAL));
    183:     PetscCall(PetscOptionsBoolGroup("-pep_target_imaginary","Compute eigenvalues with imaginary parts closest to target","PEPSetWhichEigenpairs",&flg));
    184:     if (flg) PetscCall(PEPSetWhichEigenpairs(pep,PEP_TARGET_IMAGINARY));
    185:     PetscCall(PetscOptionsBoolGroupEnd("-pep_all","Compute all eigenvalues in an interval or a region","PEPSetWhichEigenpairs",&flg));
    186:     if (flg) PetscCall(PEPSetWhichEigenpairs(pep,PEP_ALL));

    188:     PetscCall(PetscOptionsScalar("-pep_target","Value of the target","PEPSetTarget",pep->target,&s,&flg));
    189:     if (flg) {
    190:       if (pep->which!=PEP_TARGET_REAL && pep->which!=PEP_TARGET_IMAGINARY) PetscCall(PEPSetWhichEigenpairs(pep,PEP_TARGET_MAGNITUDE));
    191:       PetscCall(PEPSetTarget(pep,s));
    192:     }

    194:     k = 2;
    195:     PetscCall(PetscOptionsRealArray("-pep_interval","Computational interval (two real values separated with a comma without spaces)","PEPSetInterval",array,&k,&flg));
    196:     if (flg) {
    197:       PetscCheck(k>1,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_SIZ,"Must pass two values in -pep_interval (comma-separated without spaces)");
    198:       PetscCall(PEPSetWhichEigenpairs(pep,PEP_ALL));
    199:       PetscCall(PEPSetInterval(pep,array[0],array[1]));
    200:     }

    202:     /* -----------------------------------------------------------------------*/
    203:     /*
    204:       Cancels all monitors hardwired into code before call to PEPSetFromOptions()
    205:     */
    206:     PetscCall(PetscOptionsBool("-pep_monitor_cancel","Remove any hardwired monitor routines","PEPMonitorCancel",PETSC_FALSE,&flg,&set));
    207:     if (set && flg) PetscCall(PEPMonitorCancel(pep));
    208:     PetscCall(PEPMonitorSetFromOptions(pep,"-pep_monitor","first_approximation",NULL,PETSC_FALSE));
    209:     PetscCall(PEPMonitorSetFromOptions(pep,"-pep_monitor_all","all_approximations",NULL,PETSC_TRUE));
    210:     PetscCall(PEPMonitorSetFromOptions(pep,"-pep_monitor_conv","convergence_history",NULL,PETSC_FALSE));

    212:     /* -----------------------------------------------------------------------*/
    213:     PetscCall(PetscOptionsName("-pep_view","Print detailed information on solver used","PEPView",&set));
    214:     PetscCall(PetscOptionsName("-pep_view_vectors","View computed eigenvectors","PEPVectorsView",&set));
    215:     PetscCall(PetscOptionsName("-pep_view_values","View computed eigenvalues","PEPValuesView",&set));
    216:     PetscCall(PetscOptionsName("-pep_converged_reason","Print reason for convergence, and number of iterations","PEPConvergedReasonView",&set));
    217:     PetscCall(PetscOptionsName("-pep_error_absolute","Print absolute errors of each eigenpair","PEPErrorView",&set));
    218:     PetscCall(PetscOptionsName("-pep_error_relative","Print relative errors of each eigenpair","PEPErrorView",&set));
    219:     PetscCall(PetscOptionsName("-pep_error_backward","Print backward errors of each eigenpair","PEPErrorView",&set));

    221:     PetscTryTypeMethod(pep,setfromoptions,PetscOptionsObject);
    222:     PetscCall(PetscObjectProcessOptionsHandlers((PetscObject)pep,PetscOptionsObject));
    223:   PetscOptionsEnd();

    225:   if (!pep->V) PetscCall(PEPGetBV(pep,&pep->V));
    226:   PetscCall(BVSetFromOptions(pep->V));
    227:   if (!pep->rg) PetscCall(PEPGetRG(pep,&pep->rg));
    228:   PetscCall(RGSetFromOptions(pep->rg));
    229:   if (!pep->ds) PetscCall(PEPGetDS(pep,&pep->ds));
    230:   PetscCall(PEPSetDSType(pep));
    231:   PetscCall(DSSetFromOptions(pep->ds));
    232:   if (!pep->st) PetscCall(PEPGetST(pep,&pep->st));
    233:   PetscCall(PEPSetDefaultST(pep));
    234:   PetscCall(STSetFromOptions(pep->st));
    235:   if (!pep->refineksp) PetscCall(PEPRefineGetKSP(pep,&pep->refineksp));
    236:   PetscCall(KSPSetFromOptions(pep->refineksp));
    237:   PetscFunctionReturn(PETSC_SUCCESS);
    238: }

    240: /*@
    241:    PEPGetTolerances - Gets the tolerance and maximum iteration count used
    242:    by the `PEP` convergence tests.

    244:    Not Collective

    246:    Input Parameter:
    247: .  pep - the polynomial eigensolver context

    249:    Output Parameters:
    250: +  tol - the convergence tolerance
    251: -  maxits - maximum number of iterations

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

    256:    Level: intermediate

    258: .seealso: [](ch:pep), `PEPSetTolerances()`
    259: @*/
    260: PetscErrorCode PEPGetTolerances(PEP pep,PetscReal *tol,PetscInt *maxits)
    261: {
    262:   PetscFunctionBegin;
    264:   if (tol)    *tol    = pep->tol;
    265:   if (maxits) *maxits = pep->max_it;
    266:   PetscFunctionReturn(PETSC_SUCCESS);
    267: }

    269: /*@
    270:    PEPSetTolerances - Sets the tolerance and maximum iteration count used
    271:    by the `PEP` convergence tests.

    273:    Logically Collective

    275:    Input Parameters:
    276: +  pep    - the polynomial eigensolver context
    277: .  tol    - the convergence tolerance
    278: -  maxits - maximum number of iterations to use

    280:    Options Database Keys:
    281: +  -pep_tol \<tol\>       - sets the convergence tolerance
    282: -  -pep_max_it \<maxits\> - sets the maximum number of iterations allowed

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

    290:    Level: intermediate

    292: .seealso: [](ch:pep), `PEPGetTolerances()`
    293: @*/
    294: PetscErrorCode PEPSetTolerances(PEP pep,PetscReal tol,PetscInt maxits)
    295: {
    296:   PetscFunctionBegin;
    300:   if (tol == (PetscReal)PETSC_DETERMINE) {
    301:     pep->tol   = PETSC_DETERMINE;
    302:     pep->state = PEP_STATE_INITIAL;
    303:   } else if (tol != (PetscReal)PETSC_CURRENT) {
    304:     PetscCheck(tol>0.0,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of tol. Must be > 0");
    305:     pep->tol = tol;
    306:   }
    307:   if (maxits == PETSC_DETERMINE) {
    308:     pep->max_it = PETSC_DETERMINE;
    309:     pep->state  = PEP_STATE_INITIAL;
    310:   } else if (maxits == PETSC_UNLIMITED) {
    311:     pep->max_it = PETSC_INT_MAX;
    312:   } else if (maxits != PETSC_CURRENT) {
    313:     PetscCheck(maxits>0,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of maxits. Must be > 0");
    314:     pep->max_it = maxits;
    315:   }
    316:   PetscFunctionReturn(PETSC_SUCCESS);
    317: }

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

    323:    Not Collective

    325:    Input Parameter:
    326: .  pep - the polynomial eigensolver context

    328:    Output Parameters:
    329: +  nev - number of eigenvalues to compute
    330: .  ncv - the maximum dimension of the subspace to be used by the solver
    331: -  mpd - the maximum dimension allowed for the projected problem

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

    336:    Level: intermediate

    338: .seealso: [](ch:pep), `PEPSetDimensions()`
    339: @*/
    340: PetscErrorCode PEPGetDimensions(PEP pep,PetscInt *nev,PetscInt *ncv,PetscInt *mpd)
    341: {
    342:   PetscFunctionBegin;
    344:   if (nev) *nev = pep->nev;
    345:   if (ncv) *ncv = pep->ncv;
    346:   if (mpd) *mpd = pep->mpd;
    347:   PetscFunctionReturn(PETSC_SUCCESS);
    348: }

    350: /*@
    351:    PEPSetDimensions - Sets the number of eigenvalues to compute
    352:    and the dimension of the subspace.

    354:    Logically Collective

    356:    Input Parameters:
    357: +  pep - the polynomial eigensolver context
    358: .  nev - number of eigenvalues to compute
    359: .  ncv - the maximum dimension of the subspace to be used by the solver
    360: -  mpd - the maximum dimension allowed for the projected problem

    362:    Options Database Keys:
    363: +  -pep_nev \<nev\> - sets the number of eigenvalues
    364: .  -pep_ncv \<ncv\> - sets the dimension of the subspace
    365: -  -pep_mpd \<mpd\> - sets the maximum projected dimension

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

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

    375:     1. in cases where `nev` is small, the user sets `ncv` (a reasonable default is `2*nev`).
    376:     2. in cases where `nev` is large, the user sets `mpd`.

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

    382:    When computing all eigenvalues in an interval, see `PEPSetInterval()`, these
    383:    parameters lose relevance, and tuning must be done with
    384:    `PEPSTOARSetDimensions()`.

    386:    Level: intermediate

    388: .seealso: [](ch:pep), `PEPGetDimensions()`, `PEPSetInterval()`, `PEPSTOARSetDimensions()`
    389: @*/
    390: PetscErrorCode PEPSetDimensions(PEP pep,PetscInt nev,PetscInt ncv,PetscInt mpd)
    391: {
    392:   PetscFunctionBegin;
    397:   if (nev != PETSC_CURRENT) {
    398:     PetscCheck(nev>0,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of nev. Must be > 0");
    399:     pep->nev = nev;
    400:   }
    401:   if (ncv == PETSC_DETERMINE) {
    402:     pep->ncv = PETSC_DETERMINE;
    403:   } else if (ncv != PETSC_CURRENT) {
    404:     PetscCheck(ncv>0,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of ncv. Must be > 0");
    405:     pep->ncv = ncv;
    406:   }
    407:   if (mpd == PETSC_DETERMINE) {
    408:     pep->mpd = PETSC_DETERMINE;
    409:   } else if (mpd != PETSC_CURRENT) {
    410:     PetscCheck(mpd>0,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of mpd. Must be > 0");
    411:     pep->mpd = mpd;
    412:   }
    413:   pep->state = PEP_STATE_INITIAL;
    414:   PetscFunctionReturn(PETSC_SUCCESS);
    415: }

    417: /*@
    418:    PEPSetWhichEigenpairs - Specifies which portion of the spectrum is
    419:    to be sought.

    421:    Logically Collective

    423:    Input Parameters:
    424: +  pep   - the polynomial eigensolver context
    425: -  which - the portion of the spectrum to be sought, see `PEPWhich` for possible values

    427:    Options Database Keys:
    428: +  -pep_largest_magnitude  - sets largest eigenvalues in magnitude
    429: .  -pep_smallest_magnitude - sets smallest eigenvalues in magnitude
    430: .  -pep_largest_real       - sets largest real parts
    431: .  -pep_smallest_real      - sets smallest real parts
    432: .  -pep_largest_imaginary  - sets largest imaginary parts
    433: .  -pep_smallest_imaginary - sets smallest imaginary parts
    434: .  -pep_target_magnitude   - sets eigenvalues closest to target
    435: .  -pep_target_real        - sets real parts closest to target
    436: .  -pep_target_imaginary   - sets imaginary parts closest to target
    437: -  -pep_all                - sets all eigenvalues in an interval or region

    439:    Notes:
    440:    Not all eigensolvers implemented in `PEP` account for all the possible values
    441:    of `which`. Also, some values make sense only for certain types of
    442:    problems. If SLEPc is compiled for real numbers `PEP_LARGEST_IMAGINARY`
    443:    and `PEP_SMALLEST_IMAGINARY` use the absolute value of the imaginary part
    444:    for eigenvalue selection.

    446:    The target is a scalar value provided with `PEPSetTarget()`.

    448:    The criterion `PEP_TARGET_IMAGINARY` is available only in case PETSc and
    449:    SLEPc have been built with complex scalars.

    451:    `PEP_ALL` is intended for use in combination with an interval (see
    452:    `PEPSetInterval()`), when all eigenvalues within the interval are requested,
    453:    and also for computing all eigenvalues in a region with the `PEPCISS` solver.

    455:    Level: intermediate

    457: .seealso: [](ch:pep), `PEPGetWhichEigenpairs()`, `PEPSetTarget()`, `PEPSetInterval()`, `PEPSetDimensions()`, `PEPSetEigenvalueComparison()`, `PEPWhich`
    458: @*/
    459: PetscErrorCode PEPSetWhichEigenpairs(PEP pep,PEPWhich which)
    460: {
    461:   PetscFunctionBegin;
    464:   switch (which) {
    465:     case PEP_LARGEST_MAGNITUDE:
    466:     case PEP_SMALLEST_MAGNITUDE:
    467:     case PEP_LARGEST_REAL:
    468:     case PEP_SMALLEST_REAL:
    469:     case PEP_LARGEST_IMAGINARY:
    470:     case PEP_SMALLEST_IMAGINARY:
    471:     case PEP_TARGET_MAGNITUDE:
    472:     case PEP_TARGET_REAL:
    473: #if defined(PETSC_USE_COMPLEX)
    474:     case PEP_TARGET_IMAGINARY:
    475: #endif
    476:     case PEP_ALL:
    477:     case PEP_WHICH_USER:
    478:       if (pep->which != which) {
    479:         pep->state = PEP_STATE_INITIAL;
    480:         pep->which = which;
    481:       }
    482:       break;
    483: #if !defined(PETSC_USE_COMPLEX)
    484:     case PEP_TARGET_IMAGINARY:
    485:       SETERRQ(PetscObjectComm((PetscObject)pep),PETSC_ERR_SUP,"PEP_TARGET_IMAGINARY can be used only with complex scalars");
    486: #endif
    487:     default:
    488:       SETERRQ(PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'which' value");
    489:   }
    490:   PetscFunctionReturn(PETSC_SUCCESS);
    491: }

    493: /*@
    494:     PEPGetWhichEigenpairs - Returns which portion of the spectrum is to be
    495:     sought.

    497:     Not Collective

    499:     Input Parameter:
    500: .   pep - the polynomial eigensolver context

    502:     Output Parameter:
    503: .   which - the portion of the spectrum to be sought

    505:     Level: intermediate

    507: .seealso: [](ch:pep), `PEPSetWhichEigenpairs()`, `PEPWhich`
    508: @*/
    509: PetscErrorCode PEPGetWhichEigenpairs(PEP pep,PEPWhich *which)
    510: {
    511:   PetscFunctionBegin;
    513:   PetscAssertPointer(which,2);
    514:   *which = pep->which;
    515:   PetscFunctionReturn(PETSC_SUCCESS);
    516: }

    518: /*@C
    519:    PEPSetEigenvalueComparison - Specifies the eigenvalue comparison function
    520:    when `PEPSetWhichEigenpairs()` is set to `PEP_WHICH_USER`.

    522:    Logically Collective

    524:    Input Parameters:
    525: +  pep  - the polynomial eigensolver context
    526: .  comp - the comparison function, see `SlepcEigenvalueComparisonFn` for the calling sequence
    527: -  ctx  - a context pointer (the last parameter to the comparison function)

    529:    Level: advanced

    531: .seealso: [](ch:pep), `PEPSetWhichEigenpairs()`, `PEPWhich`
    532: @*/
    533: PetscErrorCode PEPSetEigenvalueComparison(PEP pep,SlepcEigenvalueComparisonFn *comp,void *ctx)
    534: {
    535:   PetscFunctionBegin;
    537:   pep->sc->comparison    = comp;
    538:   pep->sc->comparisonctx = ctx;
    539:   pep->which             = PEP_WHICH_USER;
    540:   PetscFunctionReturn(PETSC_SUCCESS);
    541: }

    543: /*@
    544:    PEPSetProblemType - Specifies the type of the polynomial eigenvalue problem.

    546:    Logically Collective

    548:    Input Parameters:
    549: +  pep  - the polynomial eigensolver context
    550: -  type - a known type of polynomial eigenvalue problem

    552:    Options Database Keys:
    553: +  -pep_general    - general problem with no particular structure
    554: .  -pep_hermitian  - problem whose coefficient matrices are Hermitian
    555: .  -pep_hyperbolic - Hermitian problem that satisfies the definition of hyperbolic
    556: -  -pep_gyroscopic - problem with gyroscopic structure

    558:    Notes:
    559:    See `PEPProblemType` for possible problem types.

    561:    This function is used to instruct SLEPc to exploit certain structure in
    562:    the polynomial eigenproblem. By default, no particular structure is assumed.

    564:    If the problem matrices are Hermitian (symmetric in the real case) or
    565:    Hermitian/skew-Hermitian then the solver can exploit this fact to perform
    566:    less operations or provide better stability. Hyperbolic problems are a
    567:    particular case of Hermitian problems, some solvers may treat them simply as
    568:    Hermitian.

    570:    Level: intermediate

    572: .seealso: [](ch:pep), `PEPSetOperators()`, `PEPSetType()`, `PEPGetProblemType()`, `PEPProblemType`
    573: @*/
    574: PetscErrorCode PEPSetProblemType(PEP pep,PEPProblemType type)
    575: {
    576:   PetscFunctionBegin;
    579:   PetscCheck(type==PEP_GENERAL || type==PEP_HERMITIAN || type==PEP_HYPERBOLIC || type==PEP_GYROSCOPIC,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_WRONG,"Unknown eigenvalue problem type");
    580:   if (type != pep->problem_type) {
    581:     pep->problem_type = type;
    582:     pep->state = PEP_STATE_INITIAL;
    583:   }
    584:   PetscFunctionReturn(PETSC_SUCCESS);
    585: }

    587: /*@
    588:    PEPGetProblemType - Gets the problem type from the `PEP` object.

    590:    Not Collective

    592:    Input Parameter:
    593: .  pep - the polynomial eigensolver context

    595:    Output Parameter:
    596: .  type - the problem type

    598:    Level: intermediate

    600: .seealso: [](ch:pep), `PEPSetProblemType()`, `PEPProblemType`
    601: @*/
    602: PetscErrorCode PEPGetProblemType(PEP pep,PEPProblemType *type)
    603: {
    604:   PetscFunctionBegin;
    606:   PetscAssertPointer(type,2);
    607:   *type = pep->problem_type;
    608:   PetscFunctionReturn(PETSC_SUCCESS);
    609: }

    611: /*@
    612:    PEPSetBasis - Specifies the type of polynomial basis used to describe the
    613:    polynomial eigenvalue problem.

    615:    Logically Collective

    617:    Input Parameters:
    618: +  pep   - the polynomial eigensolver context
    619: -  basis - the type of polynomial basis, see `PEPBasis` for possible values

    621:    Options Database Key:
    622: .  -pep_basis \<basis\> - Select the basis type

    624:    Note:
    625:    By default, the coefficient matrices passed via `PEPSetOperators()` are
    626:    expressed in the monomial basis, i.e.
    627:    $P(\lambda) = A_0 + \lambda A_1 + \lambda^2 A_2 + \dots + \lambda^d A_d$.
    628:    Other polynomial bases may have better numerical behavior, but the user
    629:    must then pass the coefficient matrices accordingly.

    631:    Level: intermediate

    633: .seealso: [](ch:pep), `PEPSetOperators()`, `PEPGetBasis()`, `PEPBasis`
    634: @*/
    635: PetscErrorCode PEPSetBasis(PEP pep,PEPBasis basis)
    636: {
    637:   PetscFunctionBegin;
    640:   pep->basis = basis;
    641:   PetscFunctionReturn(PETSC_SUCCESS);
    642: }

    644: /*@
    645:    PEPGetBasis - Gets the type of polynomial basis from the `PEP` object.

    647:    Not Collective

    649:    Input Parameter:
    650: .  pep - the polynomial eigensolver context

    652:    Output Parameter:
    653: .  basis - the polynomial basis

    655:    Level: intermediate

    657: .seealso: [](ch:pep), `PEPSetBasis()`, `PEPBasis`
    658: @*/
    659: PetscErrorCode PEPGetBasis(PEP pep,PEPBasis *basis)
    660: {
    661:   PetscFunctionBegin;
    663:   PetscAssertPointer(basis,2);
    664:   *basis = pep->basis;
    665:   PetscFunctionReturn(PETSC_SUCCESS);
    666: }

    668: /*@
    669:    PEPSetTrackAll - Specifies if the solver must compute the residual of all
    670:    approximate eigenpairs or not.

    672:    Logically Collective

    674:    Input Parameters:
    675: +  pep      - the polynomial eigensolver context
    676: -  trackall - whether compute all residuals or not

    678:    Notes:
    679:    If the user sets `trackall`=`PETSC_TRUE` then the solver explicitly computes
    680:    the residual for each eigenpair approximation. Computing the residual is
    681:    usually an expensive operation and solvers commonly compute the associated
    682:    residual to the first unconverged eigenpair.

    684:    The option `-pep_monitor_all` automatically activates this option.

    686:    Level: developer

    688: .seealso: [](ch:pep), `PEPGetTrackAll()`
    689: @*/
    690: PetscErrorCode PEPSetTrackAll(PEP pep,PetscBool trackall)
    691: {
    692:   PetscFunctionBegin;
    695:   pep->trackall = trackall;
    696:   PetscFunctionReturn(PETSC_SUCCESS);
    697: }

    699: /*@
    700:    PEPGetTrackAll - Returns the flag indicating whether all residual norms must
    701:    be computed or not.

    703:    Not Collective

    705:    Input Parameter:
    706: .  pep - the polynomial eigensolver context

    708:    Output Parameter:
    709: .  trackall - the returned flag

    711:    Level: developer

    713: .seealso: [](ch:pep), `PEPSetTrackAll()`
    714: @*/
    715: PetscErrorCode PEPGetTrackAll(PEP pep,PetscBool *trackall)
    716: {
    717:   PetscFunctionBegin;
    719:   PetscAssertPointer(trackall,2);
    720:   *trackall = pep->trackall;
    721:   PetscFunctionReturn(PETSC_SUCCESS);
    722: }

    724: /*@C
    725:    PEPSetConvergenceTestFunction - Sets a function to compute the error estimate
    726:    used in the convergence test.

    728:    Logically Collective

    730:    Input Parameters:
    731: +  pep     - the polynomial eigensolver context
    732: .  conv    - convergence test function, see `PEPConvergenceTestFn` for the calling sequence
    733: .  ctx     - context for private data for the convergence routine (may be `NULL`)
    734: -  destroy - a routine for destroying the context (may be `NULL`), see `PetscCtxDestroyFn`
    735:              for the calling sequence

    737:    Notes:
    738:    When this is called with a user-defined function, then the convergence
    739:    criterion is set to `PEP_CONV_USER`, see `PEPSetConvergenceTest()`.

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

    744:    Level: advanced

    746: .seealso: [](ch:pep), `PEPSetConvergenceTest()`, `PEPSetTolerances()`
    747: @*/
    748: PetscErrorCode PEPSetConvergenceTestFunction(PEP pep,PEPConvergenceTestFn *conv,void *ctx,PetscCtxDestroyFn *destroy)
    749: {
    750:   PetscFunctionBegin;
    752:   if (pep->convergeddestroy) PetscCall((*pep->convergeddestroy)(&pep->convergedctx));
    753:   pep->convergeduser    = conv;
    754:   pep->convergeddestroy = destroy;
    755:   pep->convergedctx     = ctx;
    756:   if (conv == PEPConvergedRelative) pep->conv = PEP_CONV_REL;
    757:   else if (conv == PEPConvergedNorm) pep->conv = PEP_CONV_NORM;
    758:   else if (conv == PEPConvergedAbsolute) pep->conv = PEP_CONV_ABS;
    759:   else {
    760:     pep->conv      = PEP_CONV_USER;
    761:     pep->converged = pep->convergeduser;
    762:   }
    763:   PetscFunctionReturn(PETSC_SUCCESS);
    764: }

    766: /*@
    767:    PEPSetConvergenceTest - Specifies how to compute the error estimate
    768:    used in the convergence test.

    770:    Logically Collective

    772:    Input Parameters:
    773: +  pep  - the polynomial eigensolver context
    774: -  conv - the type of convergence test, see `PEPConv` for possible values

    776:    Options Database Keys:
    777: +  -pep_conv_abs  - sets the absolute convergence test
    778: .  -pep_conv_rel  - sets the convergence test relative to the eigenvalue
    779: .  -pep_conv_norm - sets the convergence test relative to the matrix norms
    780: -  -pep_conv_user - selects the user-defined convergence test

    782:    Level: intermediate

    784: .seealso: [](ch:pep), `PEPGetConvergenceTest()`, `PEPSetConvergenceTestFunction()`, `PEPSetStoppingTest()`, `PEPConv`
    785: @*/
    786: PetscErrorCode PEPSetConvergenceTest(PEP pep,PEPConv conv)
    787: {
    788:   PetscFunctionBegin;
    791:   switch (conv) {
    792:     case PEP_CONV_ABS:  pep->converged = PEPConvergedAbsolute; break;
    793:     case PEP_CONV_REL:  pep->converged = PEPConvergedRelative; break;
    794:     case PEP_CONV_NORM: pep->converged = PEPConvergedNorm; break;
    795:     case PEP_CONV_USER:
    796:       PetscCheck(pep->convergeduser,PetscObjectComm((PetscObject)pep),PETSC_ERR_ORDER,"Must call PEPSetConvergenceTestFunction() first");
    797:       pep->converged = pep->convergeduser;
    798:       break;
    799:     default:
    800:       SETERRQ(PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'conv' value");
    801:   }
    802:   pep->conv = conv;
    803:   PetscFunctionReturn(PETSC_SUCCESS);
    804: }

    806: /*@
    807:    PEPGetConvergenceTest - Gets the method used to compute the error estimate
    808:    used in the convergence test.

    810:    Not Collective

    812:    Input Parameter:
    813: .  pep   - the polynomial eigensolver context

    815:    Output Parameter:
    816: .  conv  - the type of convergence test

    818:    Level: intermediate

    820: .seealso: [](ch:pep), `PEPSetConvergenceTest()`, `PEPConv`
    821: @*/
    822: PetscErrorCode PEPGetConvergenceTest(PEP pep,PEPConv *conv)
    823: {
    824:   PetscFunctionBegin;
    826:   PetscAssertPointer(conv,2);
    827:   *conv = pep->conv;
    828:   PetscFunctionReturn(PETSC_SUCCESS);
    829: }

    831: /*@C
    832:    PEPSetStoppingTestFunction - Sets a function to decide when to stop the outer
    833:    iteration of the eigensolver.

    835:    Logically Collective

    837:    Input Parameters:
    838: +  pep     - the polynomial eigensolver context
    839: .  stop    - stopping test function, see `PEPStoppingTestFn` for the calling sequence
    840: .  ctx     - context for private data for the stopping routine (may be `NULL`)
    841: -  destroy - a routine for destroying the context (may be `NULL`), see `PetscCtxDestroyFn`
    842:              for the calling sequence

    844:    Note:
    845:    When implementing a function for this, normal usage is to first call the
    846:    default routine `PEPStoppingBasic()` and then set `reason` to `PEP_CONVERGED_USER`
    847:    if some user-defined conditions have been met. To let the eigensolver continue
    848:    iterating, the result must be left as `PEP_CONVERGED_ITERATING`.

    850:    Level: advanced

    852: .seealso: [](ch:pep), `PEPSetStoppingTest()`, `PEPStoppingBasic()`
    853: @*/
    854: PetscErrorCode PEPSetStoppingTestFunction(PEP pep,PEPStoppingTestFn *stop,void *ctx,PetscCtxDestroyFn *destroy)
    855: {
    856:   PetscFunctionBegin;
    858:   if (pep->stoppingdestroy) PetscCall((*pep->stoppingdestroy)(&pep->stoppingctx));
    859:   pep->stoppinguser    = stop;
    860:   pep->stoppingdestroy = destroy;
    861:   pep->stoppingctx     = ctx;
    862:   if (stop == PEPStoppingBasic) pep->stop = PEP_STOP_BASIC;
    863:   else {
    864:     pep->stop     = PEP_STOP_USER;
    865:     pep->stopping = pep->stoppinguser;
    866:   }
    867:   PetscFunctionReturn(PETSC_SUCCESS);
    868: }

    870: /*@
    871:    PEPSetStoppingTest - Specifies how to decide the termination of the outer
    872:    loop of the eigensolver.

    874:    Logically Collective

    876:    Input Parameters:
    877: +  pep  - the polynomial eigensolver context
    878: -  stop - the type of stopping test, see `PEPStop`

    880:    Options Database Keys:
    881: +  -pep_stop_basic - sets the default stopping test
    882: -  -pep_stop_user  - selects the user-defined stopping test

    884:    Level: advanced

    886: .seealso: [](ch:pep), `PEPGetStoppingTest()`, `PEPSetStoppingTestFunction()`, `PEPSetConvergenceTest()`, `PEPStop`
    887: @*/
    888: PetscErrorCode PEPSetStoppingTest(PEP pep,PEPStop stop)
    889: {
    890:   PetscFunctionBegin;
    893:   switch (stop) {
    894:     case PEP_STOP_BASIC: pep->stopping = PEPStoppingBasic; break;
    895:     case PEP_STOP_USER:
    896:       PetscCheck(pep->stoppinguser,PetscObjectComm((PetscObject)pep),PETSC_ERR_ORDER,"Must call PEPSetStoppingTestFunction() first");
    897:       pep->stopping = pep->stoppinguser;
    898:       break;
    899:     default:
    900:       SETERRQ(PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'stop' value");
    901:   }
    902:   pep->stop = stop;
    903:   PetscFunctionReturn(PETSC_SUCCESS);
    904: }

    906: /*@
    907:    PEPGetStoppingTest - Gets the method used to decide the termination of the outer
    908:    loop of the eigensolver.

    910:    Not Collective

    912:    Input Parameter:
    913: .  pep   - the polynomial eigensolver context

    915:    Output Parameter:
    916: .  stop  - the type of stopping test

    918:    Level: advanced

    920: .seealso: [](ch:pep), `PEPSetStoppingTest()`, `PEPStop`
    921: @*/
    922: PetscErrorCode PEPGetStoppingTest(PEP pep,PEPStop *stop)
    923: {
    924:   PetscFunctionBegin;
    926:   PetscAssertPointer(stop,2);
    927:   *stop = pep->stop;
    928:   PetscFunctionReturn(PETSC_SUCCESS);
    929: }

    931: /*@
    932:    PEPSetScale - Specifies the scaling strategy to be used.

    934:    Collective

    936:    Input Parameters:
    937: +  pep    - the polynomial eigensolver context
    938: .  scale  - scaling strategy, see `PEPScale` for possible values
    939: .  alpha  - the scaling factor used in the scalar strategy
    940: .  Dl     - the left diagonal matrix of the diagonal scaling algorithm
    941: .  Dr     - the right diagonal matrix of the diagonal scaling algorithm
    942: .  its    - number of iterations of the diagonal scaling algorithm
    943: -  lambda - approximation to wanted eigenvalues (modulus)

    945:    Options Database Keys:
    946: +  -pep_scale \<scale\>         - set the scaling type, one of `none`,`scalar`,`diagonal`,`both`
    947: .  -pep_scale_factor \<alpha\>  - set the scaling factor
    948: .  -pep_scale_its \<its\>       - set the number of iterations
    949: -  -pep_scale_lambda \<lambda\> - set the approximation to eigenvalues

    951:    Notes:
    952:    There are two non-exclusive scaling strategies, scalar and diagonal.
    953:    See discussion in section [](#sec:scaling).

    955:    In the scalar strategy, scaling is applied to the eigenvalue, that is,
    956:    $\mu = \lambda/\alpha$ is the new eigenvalue and all matrices are scaled
    957:    accordingly. After solving the scaled problem, the original $\lambda$ is
    958:    recovered. Parameter `alpha` must be positive. Use `PETSC_DETERMINE` to let
    959:    the solver compute a reasonable scaling factor, and `PETSC_CURRENT` to
    960:    retain a previously set value.

    962:    In the diagonal strategy, the solver works implicitly with matrix $D_\ell P(\lambda)D_r$,
    963:    where $D_\ell$ and $D_r$ are appropriate diagonal matrices. This improves the accuracy
    964:    of the computed results in some cases. The user may provide the `Dl` and `Dr`
    965:    matrices represented as `Vec` objects storing diagonal elements. If not
    966:    provided, these matrices are computed internally. This option requires
    967:    that the polynomial coefficient matrices are of `MATAIJ` type.
    968:    The parameter `its` is the number of iterations performed by the method.
    969:    Parameter `lambda` must be positive. Use `PETSC_DETERMINE` or set `lambda` = 1.0
    970:    if no information about eigenvalues is available. `PETSC_CURRENT` can also
    971:    be used to leave `its` and `lambda` unchanged.

    973:    Level: intermediate

    975: .seealso: [](ch:pep), [](#sec:scaling), `PEPGetScale()`
    976: @*/
    977: PetscErrorCode PEPSetScale(PEP pep,PEPScale scale,PetscReal alpha,Vec Dl,Vec Dr,PetscInt its,PetscReal lambda)
    978: {
    979:   PetscFunctionBegin;
    982:   pep->scale = scale;
    983:   if (scale==PEP_SCALE_SCALAR || scale==PEP_SCALE_BOTH) {
    985:     if (alpha == (PetscReal)PETSC_DETERMINE) {
    986:       pep->sfactor = 0.0;
    987:       pep->sfactor_set = PETSC_FALSE;
    988:     } else if (alpha != (PetscReal)PETSC_CURRENT) {
    989:       PetscCheck(alpha>0.0,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of alpha. Must be > 0");
    990:       pep->sfactor = alpha;
    991:       pep->sfactor_set = PETSC_TRUE;
    992:     }
    993:   }
    994:   if (scale==PEP_SCALE_DIAGONAL || scale==PEP_SCALE_BOTH) {
    995:     if (Dl) {
    997:       PetscCheckSameComm(pep,1,Dl,4);
    998:       PetscCall(PetscObjectReference((PetscObject)Dl));
    999:       PetscCall(VecDestroy(&pep->Dl));
    1000:       pep->Dl = Dl;
    1001:     }
    1002:     if (Dr) {
    1004:       PetscCheckSameComm(pep,1,Dr,5);
    1005:       PetscCall(PetscObjectReference((PetscObject)Dr));
    1006:       PetscCall(VecDestroy(&pep->Dr));
    1007:       pep->Dr = Dr;
    1008:     }
    1011:     if (its==PETSC_DETERMINE) pep->sits = 5;
    1012:     else if (its!=PETSC_CURRENT) {
    1013:       PetscCheck(its>0,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of its. Must be > 0");
    1014:       pep->sits = its;
    1015:     }
    1016:     if (lambda == (PetscReal)PETSC_DETERMINE) pep->slambda = 1.0;
    1017:     else if (lambda != (PetscReal)PETSC_CURRENT) {
    1018:       PetscCheck(lambda>0.0,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of lambda. Must be > 0");
    1019:       pep->slambda = lambda;
    1020:     }
    1021:   }
    1022:   pep->state = PEP_STATE_INITIAL;
    1023:   PetscFunctionReturn(PETSC_SUCCESS);
    1024: }

    1026: /*@
    1027:    PEPGetScale - Gets the scaling strategy used by the `PEP` object, and the
    1028:    associated parameters.

    1030:    Not Collective

    1032:    Input Parameter:
    1033: .  pep - the polynomial eigensolver context

    1035:    Output Parameters:
    1036: +  scale  - scaling strategy
    1037: .  alpha  - the scaling factor used in the scalar strategy
    1038: .  Dl     - the left diagonal matrix of the diagonal scaling algorithm
    1039: .  Dr     - the right diagonal matrix of the diagonal scaling algorithm
    1040: .  its    - number of iterations of the diagonal scaling algorithm
    1041: -  lambda - approximation to wanted eigenvalues (modulus)

    1043:    Notes:
    1044:    The user can specify `NULL` for any parameter that is not needed.

    1046:    If `Dl` or `Dr` were not set by the user, then the ones computed internally are
    1047:    returned (or a `NULL` pointer if called before `PEPSetUp()`).

    1049:    Level: intermediate

    1051: .seealso: [](ch:pep), `PEPSetScale()`, `PEPSetUp()`
    1052: @*/
    1053: PetscErrorCode PEPGetScale(PEP pep,PEPScale *scale,PetscReal *alpha,Vec *Dl,Vec *Dr,PetscInt *its,PetscReal *lambda)
    1054: {
    1055:   PetscFunctionBegin;
    1057:   if (scale)  *scale  = pep->scale;
    1058:   if (alpha)  *alpha  = pep->sfactor;
    1059:   if (Dl)     *Dl     = pep->Dl;
    1060:   if (Dr)     *Dr     = pep->Dr;
    1061:   if (its)    *its    = pep->sits;
    1062:   if (lambda) *lambda = pep->slambda;
    1063:   PetscFunctionReturn(PETSC_SUCCESS);
    1064: }

    1066: /*@
    1067:    PEPSetExtract - Specifies the extraction strategy to be used.

    1069:    Logically Collective

    1071:    Input Parameters:
    1072: +  pep     - the polynomial eigensolver context
    1073: -  extract - extraction strategy, see `PEPExtract` for possible values

    1075:    Options Database Key:
    1076: .  -pep_extract \<extract\> - extraction type, one of `none`,`norm`,`residual`,`structured`

    1078:    Note:
    1079:    This is relevant for solvers based on linearization. Once the solver has
    1080:    converged, the polynomial eigenvectors can be extracted from the
    1081:    eigenvectors of the linearized problem in different ways. See the
    1082:    discussion in section [](#sec:pepextr).

    1084:    Level: intermediate

    1086: .seealso: [](ch:pep), [](#sec:pepextr), `PEPExtract`, `PEPGetExtract()`
    1087: @*/
    1088: PetscErrorCode PEPSetExtract(PEP pep,PEPExtract extract)
    1089: {
    1090:   PetscFunctionBegin;
    1093:   pep->extract = extract;
    1094:   PetscFunctionReturn(PETSC_SUCCESS);
    1095: }

    1097: /*@
    1098:    PEPGetExtract - Gets the extraction strategy used by the `PEP` object.

    1100:    Not Collective

    1102:    Input Parameter:
    1103: .  pep - the polynomial eigensolver context

    1105:    Output Parameter:
    1106: .  extract - extraction strategy

    1108:    Level: intermediate

    1110: .seealso: [](ch:pep), `PEPSetExtract()`, `PEPExtract`
    1111: @*/
    1112: PetscErrorCode PEPGetExtract(PEP pep,PEPExtract *extract)
    1113: {
    1114:   PetscFunctionBegin;
    1116:   PetscAssertPointer(extract,2);
    1117:   *extract = pep->extract;
    1118:   PetscFunctionReturn(PETSC_SUCCESS);
    1119: }

    1121: /*@
    1122:    PEPSetRefine - Specifies the refinement type (and options) to be used
    1123:    after the solve.

    1125:    Logically Collective

    1127:    Input Parameters:
    1128: +  pep    - the polynomial eigensolver context
    1129: .  refine - refinement type, see `PEPRefine` for possible values
    1130: .  npart  - number of partitions of the communicator
    1131: .  tol    - the convergence tolerance
    1132: .  its    - maximum number of refinement iterations
    1133: -  scheme - the scheme for solving the involved linear systems, see `PEPRefineScheme`
    1134:             for possible values

    1136:    Options Database Keys:
    1137: +  -pep_refine \<refine\>           - set the refinement type, one of `none`,`simple`,`multiple`
    1138: .  -pep_refine_partitions \<npart\> - set the number of partitions
    1139: .  -pep_refine_tol \<tol\>         - set the tolerance
    1140: .  -pep_refine_its \<its\>         - set the number of iterations
    1141: -  -pep_refine_scheme \<scheme\>   - set the scheme for the linear solves, `schur`,`mbe`, or `explicit`

    1143:    Notes:
    1144:    This function configures the parameters of Newton iterative refinement,
    1145:    see section [](#sec:refine) for a discussion of the different strategies.

    1147:    By default, iterative refinement is disabled, since it may be very
    1148:    costly. There are two possible refinement strategies, simple and multiple.
    1149:    The simple approach performs iterative refinement on each of the
    1150:    converged eigenpairs individually, whereas the multiple strategy works
    1151:    with the invariant pair as a whole, refining all eigenpairs simultaneously.
    1152:    The latter may be required for the case of multiple eigenvalues.

    1154:    In some cases, especially when using direct solvers within the
    1155:    iterative refinement method, it may be helpful for improved scalability
    1156:    to split the communicator in several partitions. The `npart` parameter
    1157:    indicates how many partitions to use (defaults to 1).

    1159:    The `tol` and `its` parameters specify the stopping criterion. In the simple
    1160:    method, refinement continues until the residual of each eigenpair is
    1161:    below the tolerance (`tol` defaults to the `PEP` tolerance, but may be set to a
    1162:    different value). In contrast, the multiple method simply performs its
    1163:    refinement iterations (just one by default).

    1165:    The `scheme` argument is used to change the way in which linear systems are
    1166:    solved. Possible choices are explicit, mixed block elimination (MBE),
    1167:    and Schur complement.

    1169:    Use `PETSC_CURRENT` to retain the current value of `npart`, `tol` or `its`. Use
    1170:    `PETSC_DETERMINE` to assign a default value.

    1172:    Level: intermediate

    1174: .seealso: [](ch:pep), [](#sec:refine), `PEPGetRefine()`
    1175: @*/
    1176: PetscErrorCode PEPSetRefine(PEP pep,PEPRefine refine,PetscInt npart,PetscReal tol,PetscInt its,PEPRefineScheme scheme)
    1177: {
    1178:   PetscMPIInt    size;

    1180:   PetscFunctionBegin;
    1187:   pep->refine = refine;
    1188:   if (refine) {  /* process parameters only if not REFINE_NONE */
    1189:     if (npart!=pep->npart) {
    1190:       PetscCall(PetscSubcommDestroy(&pep->refinesubc));
    1191:       PetscCall(KSPDestroy(&pep->refineksp));
    1192:     }
    1193:     if (npart == PETSC_DETERMINE) {
    1194:       pep->npart = 1;
    1195:     } else if (npart != PETSC_CURRENT) {
    1196:       PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)pep),&size));
    1197:       PetscCheck(npart>0 && npart<=size,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of npart");
    1198:       pep->npart = npart;
    1199:     }
    1200:     if (tol == (PetscReal)PETSC_DETERMINE) {
    1201:       pep->rtol = PETSC_DETERMINE;
    1202:     } else if (tol != (PetscReal)PETSC_CURRENT) {
    1203:       PetscCheck(tol>0.0,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of tol. Must be > 0");
    1204:       pep->rtol = tol;
    1205:     }
    1206:     if (its==PETSC_DETERMINE) {
    1207:       pep->rits = PETSC_DETERMINE;
    1208:     } else if (its != PETSC_CURRENT) {
    1209:       PetscCheck(its>=0,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of its. Must be >= 0");
    1210:       pep->rits = its;
    1211:     }
    1212:     pep->scheme = scheme;
    1213:   }
    1214:   pep->state = PEP_STATE_INITIAL;
    1215:   PetscFunctionReturn(PETSC_SUCCESS);
    1216: }

    1218: /*@
    1219:    PEPGetRefine - Gets the refinement strategy used by the `PEP` object, and the
    1220:    associated parameters.

    1222:    Not Collective

    1224:    Input Parameter:
    1225: .  pep - the polynomial eigensolver context

    1227:    Output Parameters:
    1228: +  refine - refinement type
    1229: .  npart  - number of partitions of the communicator
    1230: .  tol    - the convergence tolerance
    1231: .  its    - maximum number of refinement iterations
    1232: -  scheme - the scheme used for solving linear systems

    1234:    Note:
    1235:    The user can specify `NULL` for any parameter that is not needed.

    1237:    Level: intermediate

    1239: .seealso: [](ch:pep), `PEPSetRefine()`
    1240: @*/
    1241: PetscErrorCode PEPGetRefine(PEP pep,PEPRefine *refine,PetscInt *npart,PetscReal *tol,PetscInt *its,PEPRefineScheme *scheme)
    1242: {
    1243:   PetscFunctionBegin;
    1245:   if (refine) *refine = pep->refine;
    1246:   if (npart)  *npart  = pep->npart;
    1247:   if (tol)    *tol    = pep->rtol;
    1248:   if (its)    *its    = pep->rits;
    1249:   if (scheme) *scheme = pep->scheme;
    1250:   PetscFunctionReturn(PETSC_SUCCESS);
    1251: }

    1253: /*@
    1254:    PEPSetOptionsPrefix - Sets the prefix used for searching for all
    1255:    `PEP` options in the database.

    1257:    Logically Collective

    1259:    Input Parameters:
    1260: +  pep    - the polynomial eigensolver context
    1261: -  prefix - the prefix string to prepend to all `PEP` option requests

    1263:    Notes:
    1264:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    1265:    The first character of all runtime options is AUTOMATICALLY the
    1266:    hyphen.

    1268:    For example, to distinguish between the runtime options for two
    1269:    different `PEP` contexts, one could call
    1270: .vb
    1271:    PEPSetOptionsPrefix(pep1,"qeig1_")
    1272:    PEPSetOptionsPrefix(pep2,"qeig2_")
    1273: .ve

    1275:    Level: advanced

    1277: .seealso: [](ch:pep), `PEPAppendOptionsPrefix()`, `PEPGetOptionsPrefix()`
    1278: @*/
    1279: PetscErrorCode PEPSetOptionsPrefix(PEP pep,const char prefix[])
    1280: {
    1281:   PetscFunctionBegin;
    1283:   if (!pep->st) PetscCall(PEPGetST(pep,&pep->st));
    1284:   PetscCall(STSetOptionsPrefix(pep->st,prefix));
    1285:   if (!pep->V) PetscCall(PEPGetBV(pep,&pep->V));
    1286:   PetscCall(BVSetOptionsPrefix(pep->V,prefix));
    1287:   if (!pep->ds) PetscCall(PEPGetDS(pep,&pep->ds));
    1288:   PetscCall(DSSetOptionsPrefix(pep->ds,prefix));
    1289:   if (!pep->rg) PetscCall(PEPGetRG(pep,&pep->rg));
    1290:   PetscCall(RGSetOptionsPrefix(pep->rg,prefix));
    1291:   PetscCall(PetscObjectSetOptionsPrefix((PetscObject)pep,prefix));
    1292:   PetscFunctionReturn(PETSC_SUCCESS);
    1293: }

    1295: /*@
    1296:    PEPAppendOptionsPrefix - Appends to the prefix used for searching for all
    1297:    `PEP` options in the database.

    1299:    Logically Collective

    1301:    Input Parameters:
    1302: +  pep    - the polynomial eigensolver context
    1303: -  prefix - the prefix string to prepend to all `PEP` option requests

    1305:    Notes:
    1306:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    1307:    The first character of all runtime options is AUTOMATICALLY the hyphen.

    1309:    Level: advanced

    1311: .seealso: [](ch:pep), `PEPSetOptionsPrefix()`, `PEPGetOptionsPrefix()`
    1312: @*/
    1313: PetscErrorCode PEPAppendOptionsPrefix(PEP pep,const char prefix[])
    1314: {
    1315:   PetscFunctionBegin;
    1317:   if (!pep->st) PetscCall(PEPGetST(pep,&pep->st));
    1318:   PetscCall(STAppendOptionsPrefix(pep->st,prefix));
    1319:   if (!pep->V) PetscCall(PEPGetBV(pep,&pep->V));
    1320:   PetscCall(BVAppendOptionsPrefix(pep->V,prefix));
    1321:   if (!pep->ds) PetscCall(PEPGetDS(pep,&pep->ds));
    1322:   PetscCall(DSAppendOptionsPrefix(pep->ds,prefix));
    1323:   if (!pep->rg) PetscCall(PEPGetRG(pep,&pep->rg));
    1324:   PetscCall(RGAppendOptionsPrefix(pep->rg,prefix));
    1325:   PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)pep,prefix));
    1326:   PetscFunctionReturn(PETSC_SUCCESS);
    1327: }

    1329: /*@
    1330:    PEPGetOptionsPrefix - Gets the prefix used for searching for all
    1331:    `PEP` options in the database.

    1333:    Not Collective

    1335:    Input Parameter:
    1336: .  pep - the polynomial eigensolver context

    1338:    Output Parameter:
    1339: .  prefix - pointer to the prefix string used is returned

    1341:    Level: advanced

    1343: .seealso: [](ch:pep), `PEPSetOptionsPrefix()`, `PEPAppendOptionsPrefix()`
    1344: @*/
    1345: PetscErrorCode PEPGetOptionsPrefix(PEP pep,const char *prefix[])
    1346: {
    1347:   PetscFunctionBegin;
    1349:   PetscAssertPointer(prefix,2);
    1350:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)pep,prefix));
    1351:   PetscFunctionReturn(PETSC_SUCCESS);
    1352: }