Date: 2022-08-09T09:05:48+00:00

Actual source code: pepopts.c
slepc-3.17.2 2022-08-09
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain

      6:    This file is part of SLEPc.
      7:    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
      8:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      9: */
     10: /*
     11:    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 on pep

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

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

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

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

     71:    Collective on pep

     73:    Input Parameters:
     74: .  pep - the polynomial eigensolver context

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

     79:    Level: beginner

     81: .seealso: PEPSetOptionsPrefix()
     82: @*/
     83: PetscErrorCode PEPSetFromOptions(PEP pep)
     84: {
     85:   PetscErrorCode  ierr;
     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;

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

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

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

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

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

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

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

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

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

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

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

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

    193:     k = 2;
    194:     PetscOptionsRealArray("-pep_interval","Computational interval (two real values separated with a comma without spaces)","PEPSetInterval",array,&k,&flg);
    195:     if (flg) {
    197:       PEPSetWhichEigenpairs(pep,PEP_ALL);
    198:       PEPSetInterval(pep,array[0],array[1]);
    199:     }

    201:     /* -----------------------------------------------------------------------*/
    202:     /*
    203:       Cancels all monitors hardwired into code before call to PEPSetFromOptions()
    204:     */
    205:     PetscOptionsBool("-pep_monitor_cancel","Remove any hardwired monitor routines","PEPMonitorCancel",PETSC_FALSE,&flg,&set);
    206:     if (set && flg) PEPMonitorCancel(pep);
    207:     PEPMonitorSetFromOptions(pep,"-pep_monitor","first_approximation",NULL,PETSC_FALSE);
    208:     PEPMonitorSetFromOptions(pep,"-pep_monitor_all","all_approximations",NULL,PETSC_TRUE);
    209:     PEPMonitorSetFromOptions(pep,"-pep_monitor_conv","convergence_history",NULL,PETSC_FALSE);

    211:     /* -----------------------------------------------------------------------*/
    212:     PetscOptionsName("-pep_view","Print detailed information on solver used","PEPView",NULL);
    213:     PetscOptionsName("-pep_view_vectors","View computed eigenvectors","PEPVectorsView",NULL);
    214:     PetscOptionsName("-pep_view_values","View computed eigenvalues","PEPValuesView",NULL);
    215:     PetscOptionsName("-pep_converged_reason","Print reason for convergence, and number of iterations","PEPConvergedReasonView",NULL);
    216:     PetscOptionsName("-pep_error_absolute","Print absolute errors of each eigenpair","PEPErrorView",NULL);
    217:     PetscOptionsName("-pep_error_relative","Print relative errors of each eigenpair","PEPErrorView",NULL);
    218:     PetscOptionsName("-pep_error_backward","Print backward errors of each eigenpair","PEPErrorView",NULL);

    220:     if (pep->ops->setfromoptions) (*pep->ops->setfromoptions)(PetscOptionsObject,pep);
    221:     PetscObjectProcessOptionsHandlers(PetscOptionsObject,(PetscObject)pep);
    222:   ierr = PetscOptionsEnd();

    224:   if (!pep->V) PEPGetBV(pep,&pep->V);
    225:   BVSetFromOptions(pep->V);
    226:   if (!pep->rg) PEPGetRG(pep,&pep->rg);
    227:   RGSetFromOptions(pep->rg);
    228:   if (!pep->ds) PEPGetDS(pep,&pep->ds);
    229:   DSSetFromOptions(pep->ds);
    230:   if (!pep->st) PEPGetST(pep,&pep->st);
    231:   PEPSetDefaultST(pep);
    232:   STSetFromOptions(pep->st);
    233:   if (!pep->refineksp) PEPRefineGetKSP(pep,&pep->refineksp);
    234:   KSPSetFromOptions(pep->refineksp);
    235:   PetscFunctionReturn(0);
    236: }

    238: /*@C
    239:    PEPGetTolerances - Gets the tolerance and maximum iteration count used
    240:    by the PEP convergence tests.

    242:    Not Collective

    244:    Input Parameter:
    245: .  pep - the polynomial eigensolver context

    247:    Output Parameters:
    248: +  tol - the convergence tolerance
    249: -  maxits - maximum number of iterations

    251:    Notes:
    252:    The user can specify NULL for any parameter that is not needed.

    254:    Level: intermediate

    256: .seealso: PEPSetTolerances()
    257: @*/
    258: PetscErrorCode PEPGetTolerances(PEP pep,PetscReal *tol,PetscInt *maxits)
    259: {
    261:   if (tol)    *tol    = pep->tol;
    262:   if (maxits) *maxits = pep->max_it;
    263:   PetscFunctionReturn(0);
    264: }

    266: /*@
    267:    PEPSetTolerances - Sets the tolerance and maximum iteration count used
    268:    by the PEP convergence tests.

    270:    Logically Collective on pep

    272:    Input Parameters:
    273: +  pep - the polynomial eigensolver context
    274: .  tol - the convergence tolerance
    275: -  maxits - maximum number of iterations to use

    277:    Options Database Keys:
    278: +  -pep_tol <tol> - Sets the convergence tolerance
    279: -  -pep_max_it <maxits> - Sets the maximum number of iterations allowed

    281:    Notes:
    282:    Use PETSC_DEFAULT for either argument to assign a reasonably good value.

    284:    Level: intermediate

    286: .seealso: PEPGetTolerances()
    287: @*/
    288: PetscErrorCode PEPSetTolerances(PEP pep,PetscReal tol,PetscInt maxits)
    289: {
    293:   if (tol == PETSC_DEFAULT) {
    294:     pep->tol   = PETSC_DEFAULT;
    295:     pep->state = PEP_STATE_INITIAL;
    296:   } else {
    298:     pep->tol = tol;
    299:   }
    300:   if (maxits == PETSC_DEFAULT || maxits == PETSC_DECIDE) {
    301:     pep->max_it = PETSC_DEFAULT;
    302:     pep->state  = PEP_STATE_INITIAL;
    303:   } else {
    305:     pep->max_it = maxits;
    306:   }
    307:   PetscFunctionReturn(0);
    308: }

    310: /*@C
    311:    PEPGetDimensions - Gets the number of eigenvalues to compute
    312:    and the dimension of the subspace.

    314:    Not Collective

    316:    Input Parameter:
    317: .  pep - the polynomial eigensolver context

    319:    Output Parameters:
    320: +  nev - number of eigenvalues to compute
    321: .  ncv - the maximum dimension of the subspace to be used by the solver
    322: -  mpd - the maximum dimension allowed for the projected problem

    324:    Notes:
    325:    The user can specify NULL for any parameter that is not needed.

    327:    Level: intermediate

    329: .seealso: PEPSetDimensions()
    330: @*/
    331: PetscErrorCode PEPGetDimensions(PEP pep,PetscInt *nev,PetscInt *ncv,PetscInt *mpd)
    332: {
    334:   if (nev) *nev = pep->nev;
    335:   if (ncv) *ncv = pep->ncv;
    336:   if (mpd) *mpd = pep->mpd;
    337:   PetscFunctionReturn(0);
    338: }

    340: /*@
    341:    PEPSetDimensions - Sets the number of eigenvalues to compute
    342:    and the dimension of the subspace.

    344:    Logically Collective on pep

    346:    Input Parameters:
    347: +  pep - the polynomial eigensolver context
    348: .  nev - number of eigenvalues to compute
    349: .  ncv - the maximum dimension of the subspace to be used by the solver
    350: -  mpd - the maximum dimension allowed for the projected problem

    352:    Options Database Keys:
    353: +  -pep_nev <nev> - Sets the number of eigenvalues
    354: .  -pep_ncv <ncv> - Sets the dimension of the subspace
    355: -  -pep_mpd <mpd> - Sets the maximum projected dimension

    357:    Notes:
    358:    Use PETSC_DEFAULT for ncv and mpd to assign a reasonably good value, which is
    359:    dependent on the solution method.

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

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

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

    373:    Level: intermediate

    375: .seealso: PEPGetDimensions(), PEPSetInterval(), PEPSTOARSetDimensions()
    376: @*/
    377: PetscErrorCode PEPSetDimensions(PEP pep,PetscInt nev,PetscInt ncv,PetscInt mpd)
    378: {
    384:   pep->nev = nev;
    385:   if (ncv == PETSC_DECIDE || ncv == PETSC_DEFAULT) {
    386:     pep->ncv = PETSC_DEFAULT;
    387:   } else {
    389:     pep->ncv = ncv;
    390:   }
    391:   if (mpd == PETSC_DECIDE || mpd == PETSC_DEFAULT) {
    392:     pep->mpd = PETSC_DEFAULT;
    393:   } else {
    395:     pep->mpd = mpd;
    396:   }
    397:   pep->state = PEP_STATE_INITIAL;
    398:   PetscFunctionReturn(0);
    399: }

    401: /*@
    402:    PEPSetWhichEigenpairs - Specifies which portion of the spectrum is
    403:    to be sought.

    405:    Logically Collective on pep

    407:    Input Parameters:
    408: +  pep   - eigensolver context obtained from PEPCreate()
    409: -  which - the portion of the spectrum to be sought

    411:    Possible values:
    412:    The parameter 'which' can have one of these values

    414: +     PEP_LARGEST_MAGNITUDE - largest eigenvalues in magnitude (default)
    415: .     PEP_SMALLEST_MAGNITUDE - smallest eigenvalues in magnitude
    416: .     PEP_LARGEST_REAL - largest real parts
    417: .     PEP_SMALLEST_REAL - smallest real parts
    418: .     PEP_LARGEST_IMAGINARY - largest imaginary parts
    419: .     PEP_SMALLEST_IMAGINARY - smallest imaginary parts
    420: .     PEP_TARGET_MAGNITUDE - eigenvalues closest to the target (in magnitude)
    421: .     PEP_TARGET_REAL - eigenvalues with real part closest to target
    422: .     PEP_TARGET_IMAGINARY - eigenvalues with imaginary part closest to target
    423: .     PEP_ALL - all eigenvalues contained in a given interval or region
    424: -     PEP_WHICH_USER - user defined ordering set with PEPSetEigenvalueComparison()

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

    438:    Notes:
    439:    Not all eigensolvers implemented in PEP account for all the possible values
    440:    stated above. If SLEPc is compiled for real numbers PEP_LARGEST_IMAGINARY
    441:    and PEP_SMALLEST_IMAGINARY use the absolute value of the imaginary part
    442:    for eigenvalue selection.

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

    446:    The criterion PEP_TARGET_IMAGINARY is available only in case PETSc and
    447:    SLEPc have been built with complex scalars.

    449:    PEP_ALL is intended for use in combination with an interval (see
    450:    PEPSetInterval()), when all eigenvalues within the interval are requested,
    451:    and also for computing all eigenvalues in a region with the CISS solver.
    452:    In both cases, the number of eigenvalues is unknown, so the nev parameter
    453:    has a different sense, see PEPSetDimensions().

    455:    Level: intermediate

    457: .seealso: PEPGetWhichEigenpairs(), PEPSetTarget(), PEPSetInterval(),
    458:           PEPSetDimensions(), PEPSetEigenvalueComparison(), PEPWhich
    459: @*/
    460: PetscErrorCode PEPSetWhichEigenpairs(PEP pep,PEPWhich which)
    461: {
    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(0);
    491: }

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

    497:     Not Collective

    499:     Input Parameter:
    500: .   pep - eigensolver context obtained from PEPCreate()

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

    505:     Notes:
    506:     See PEPSetWhichEigenpairs() for possible values of 'which'.

    508:     Level: intermediate

    510: .seealso: PEPSetWhichEigenpairs(), PEPWhich
    511: @*/
    512: PetscErrorCode PEPGetWhichEigenpairs(PEP pep,PEPWhich *which)
    513: {
    516:   *which = pep->which;
    517:   PetscFunctionReturn(0);
    518: }

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

    524:    Logically Collective on pep

    526:    Input Parameters:
    527: +  pep  - eigensolver context obtained from PEPCreate()
    528: .  func - a pointer to the comparison function
    529: -  ctx  - a context pointer (the last parameter to the comparison function)

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

    534: +   ar     - real part of the 1st eigenvalue
    535: .   ai     - imaginary part of the 1st eigenvalue
    536: .   br     - real part of the 2nd eigenvalue
    537: .   bi     - imaginary part of the 2nd eigenvalue
    538: .   res    - result of comparison
    539: -   ctx    - optional context, as set by PEPSetEigenvalueComparison()

    541:    Note:
    542:    The returning parameter 'res' can be
    543: +  negative - if the 1st eigenvalue is preferred to the 2st one
    544: .  zero     - if both eigenvalues are equally preferred
    545: -  positive - if the 2st eigenvalue is preferred to the 1st one

    547:    Level: advanced

    549: .seealso: PEPSetWhichEigenpairs(), PEPWhich
    550: @*/
    551: PetscErrorCode PEPSetEigenvalueComparison(PEP pep,PetscErrorCode (*func)(PetscScalar,PetscScalar,PetscScalar,PetscScalar,PetscInt*,void*),void* ctx)
    552: {
    554:   pep->sc->comparison    = func;
    555:   pep->sc->comparisonctx = ctx;
    556:   pep->which             = PEP_WHICH_USER;
    557:   PetscFunctionReturn(0);
    558: }

    560: /*@
    561:    PEPSetProblemType - Specifies the type of the polynomial eigenvalue problem.

    563:    Logically Collective on pep

    565:    Input Parameters:
    566: +  pep  - the polynomial eigensolver context
    567: -  type - a known type of polynomial eigenvalue problem

    569:    Options Database Keys:
    570: +  -pep_general - general problem with no particular structure
    571: .  -pep_hermitian - problem whose coefficient matrices are Hermitian
    572: .  -pep_hyperbolic - Hermitian problem that satisfies the definition of hyperbolic
    573: -  -pep_gyroscopic - problem with Hamiltonian structure

    575:    Notes:
    576:    Allowed values for the problem type are general (PEP_GENERAL), Hermitian
    577:    (PEP_HERMITIAN), hyperbolic (PEP_HYPERBOLIC), and gyroscopic (PEP_GYROSCOPIC).

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

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

    588:    Level: intermediate

    590: .seealso: PEPSetOperators(), PEPSetType(), PEPGetProblemType(), PEPProblemType
    591: @*/
    592: PetscErrorCode PEPSetProblemType(PEP pep,PEPProblemType type)
    593: {
    597:   if (type != pep->problem_type) {
    598:     pep->problem_type = type;
    599:     pep->state = PEP_STATE_INITIAL;
    600:   }
    601:   PetscFunctionReturn(0);
    602: }

    604: /*@
    605:    PEPGetProblemType - Gets the problem type from the PEP object.

    607:    Not Collective

    609:    Input Parameter:
    610: .  pep - the polynomial eigensolver context

    612:    Output Parameter:
    613: .  type - the problem type

    615:    Level: intermediate

    617: .seealso: PEPSetProblemType(), PEPProblemType
    618: @*/
    619: PetscErrorCode PEPGetProblemType(PEP pep,PEPProblemType *type)
    620: {
    623:   *type = pep->problem_type;
    624:   PetscFunctionReturn(0);
    625: }

    627: /*@
    628:    PEPSetBasis - Specifies the type of polynomial basis used to describe the
    629:    polynomial eigenvalue problem.

    631:    Logically Collective on pep

    633:    Input Parameters:
    634: +  pep   - the polynomial eigensolver context
    635: -  basis - the type of polynomial basis

    637:    Options Database Key:
    638: .  -pep_basis <basis> - Select the basis type

    640:    Notes:
    641:    By default, the coefficient matrices passed via PEPSetOperators() are
    642:    expressed in the monomial basis, i.e.
    643:    P(lambda) = A_0 + lambda*A_1 + lambda^2*A_2 + ... + lambda^d*A_d.
    644:    Other polynomial bases may have better numerical behaviour, but the user
    645:    must then pass the coefficient matrices accordingly.

    647:    Level: intermediate

    649: .seealso: PEPSetOperators(), PEPGetBasis(), PEPBasis
    650: @*/
    651: PetscErrorCode PEPSetBasis(PEP pep,PEPBasis basis)
    652: {
    655:   pep->basis = basis;
    656:   PetscFunctionReturn(0);
    657: }

    659: /*@
    660:    PEPGetBasis - Gets the type of polynomial basis from the PEP object.

    662:    Not Collective

    664:    Input Parameter:
    665: .  pep - the polynomial eigensolver context

    667:    Output Parameter:
    668: .  basis - the polynomial basis

    670:    Level: intermediate

    672: .seealso: PEPSetBasis(), PEPBasis
    673: @*/
    674: PetscErrorCode PEPGetBasis(PEP pep,PEPBasis *basis)
    675: {
    678:   *basis = pep->basis;
    679:   PetscFunctionReturn(0);
    680: }

    682: /*@
    683:    PEPSetTrackAll - Specifies if the solver must compute the residual of all
    684:    approximate eigenpairs or not.

    686:    Logically Collective on pep

    688:    Input Parameters:
    689: +  pep      - the eigensolver context
    690: -  trackall - whether compute all residuals or not

    692:    Notes:
    693:    If the user sets trackall=PETSC_TRUE then the solver explicitly computes
    694:    the residual for each eigenpair approximation. Computing the residual is
    695:    usually an expensive operation and solvers commonly compute the associated
    696:    residual to the first unconverged eigenpair.

    698:    The option '-pep_monitor_all' automatically activates this option.

    700:    Level: developer

    702: .seealso: PEPGetTrackAll()
    703: @*/
    704: PetscErrorCode PEPSetTrackAll(PEP pep,PetscBool trackall)
    705: {
    708:   pep->trackall = trackall;
    709:   PetscFunctionReturn(0);
    710: }

    712: /*@
    713:    PEPGetTrackAll - Returns the flag indicating whether all residual norms must
    714:    be computed or not.

    716:    Not Collective

    718:    Input Parameter:
    719: .  pep - the eigensolver context

    721:    Output Parameter:
    722: .  trackall - the returned flag

    724:    Level: developer

    726: .seealso: PEPSetTrackAll()
    727: @*/
    728: PetscErrorCode PEPGetTrackAll(PEP pep,PetscBool *trackall)
    729: {
    732:   *trackall = pep->trackall;
    733:   PetscFunctionReturn(0);
    734: }

    736: /*@C
    737:    PEPSetConvergenceTestFunction - Sets a function to compute the error estimate
    738:    used in the convergence test.

    740:    Logically Collective on pep

    742:    Input Parameters:
    743: +  pep     - eigensolver context obtained from PEPCreate()
    744: .  func    - a pointer to the convergence test function
    745: .  ctx     - context for private data for the convergence routine (may be null)
    746: -  destroy - a routine for destroying the context (may be null)

    748:    Calling Sequence of func:
    749: $   func(PEP pep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)

    751: +   pep    - eigensolver context obtained from PEPCreate()
    752: .   eigr   - real part of the eigenvalue
    753: .   eigi   - imaginary part of the eigenvalue
    754: .   res    - residual norm associated to the eigenpair
    755: .   errest - (output) computed error estimate
    756: -   ctx    - optional context, as set by PEPSetConvergenceTestFunction()

    758:    Note:
    759:    If the error estimate returned by the convergence test function is less than
    760:    the tolerance, then the eigenvalue is accepted as converged.

    762:    Level: advanced

    764: .seealso: PEPSetConvergenceTest(), PEPSetTolerances()
    765: @*/
    766: PetscErrorCode PEPSetConvergenceTestFunction(PEP pep,PetscErrorCode (*func)(PEP,PetscScalar,PetscScalar,PetscReal,PetscReal*,void*),void* ctx,PetscErrorCode (*destroy)(void*))
    767: {
    769:   if (pep->convergeddestroy) (*pep->convergeddestroy)(pep->convergedctx);
    770:   pep->convergeduser    = func;
    771:   pep->convergeddestroy = destroy;
    772:   pep->convergedctx     = ctx;
    773:   if (func == PEPConvergedRelative) pep->conv = PEP_CONV_REL;
    774:   else if (func == PEPConvergedNorm) pep->conv = PEP_CONV_NORM;
    775:   else if (func == PEPConvergedAbsolute) pep->conv = PEP_CONV_ABS;
    776:   else {
    777:     pep->conv      = PEP_CONV_USER;
    778:     pep->converged = pep->convergeduser;
    779:   }
    780:   PetscFunctionReturn(0);
    781: }

    783: /*@
    784:    PEPSetConvergenceTest - Specifies how to compute the error estimate
    785:    used in the convergence test.

    787:    Logically Collective on pep

    789:    Input Parameters:
    790: +  pep  - eigensolver context obtained from PEPCreate()
    791: -  conv - the type of convergence test

    793:    Options Database Keys:
    794: +  -pep_conv_abs    - Sets the absolute convergence test
    795: .  -pep_conv_rel    - Sets the convergence test relative to the eigenvalue
    796: .  -pep_conv_norm   - Sets the convergence test relative to the matrix norms
    797: -  -pep_conv_user   - Selects the user-defined convergence test

    799:    Note:
    800:    The parameter 'conv' can have one of these values
    801: +     PEP_CONV_ABS    - absolute error ||r||
    802: .     PEP_CONV_REL    - error relative to the eigenvalue l, ||r||/|l|
    803: .     PEP_CONV_NORM   - error relative matrix norms, ||r||/sum_i(l^i*||A_i||)
    804: -     PEP_CONV_USER   - function set by PEPSetConvergenceTestFunction()

    806:    Level: intermediate

    808: .seealso: PEPGetConvergenceTest(), PEPSetConvergenceTestFunction(), PEPSetStoppingTest(), PEPConv
    809: @*/
    810: PetscErrorCode PEPSetConvergenceTest(PEP pep,PEPConv conv)
    811: {
    814:   switch (conv) {
    815:     case PEP_CONV_ABS:  pep->converged = PEPConvergedAbsolute; break;
    816:     case PEP_CONV_REL:  pep->converged = PEPConvergedRelative; break;
    817:     case PEP_CONV_NORM: pep->converged = PEPConvergedNorm; break;
    818:     case PEP_CONV_USER:
    820:       pep->converged = pep->convergeduser;
    821:       break;
    822:     default:
    823:       SETERRQ(PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'conv' value");
    824:   }
    825:   pep->conv = conv;
    826:   PetscFunctionReturn(0);
    827: }

    829: /*@
    830:    PEPGetConvergenceTest - Gets the method used to compute the error estimate
    831:    used in the convergence test.

    833:    Not Collective

    835:    Input Parameters:
    836: .  pep   - eigensolver context obtained from PEPCreate()

    838:    Output Parameters:
    839: .  conv  - the type of convergence test

    841:    Level: intermediate

    843: .seealso: PEPSetConvergenceTest(), PEPConv
    844: @*/
    845: PetscErrorCode PEPGetConvergenceTest(PEP pep,PEPConv *conv)
    846: {
    849:   *conv = pep->conv;
    850:   PetscFunctionReturn(0);
    851: }

    853: /*@C
    854:    PEPSetStoppingTestFunction - Sets a function to decide when to stop the outer
    855:    iteration of the eigensolver.

    857:    Logically Collective on pep

    859:    Input Parameters:
    860: +  pep     - eigensolver context obtained from PEPCreate()
    861: .  func    - pointer to the stopping test function
    862: .  ctx     - context for private data for the stopping routine (may be null)
    863: -  destroy - a routine for destroying the context (may be null)

    865:    Calling Sequence of func:
    866: $   func(PEP pep,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nev,PEPConvergedReason *reason,void *ctx)

    868: +   pep    - eigensolver context obtained from PEPCreate()
    869: .   its    - current number of iterations
    870: .   max_it - maximum number of iterations
    871: .   nconv  - number of currently converged eigenpairs
    872: .   nev    - number of requested eigenpairs
    873: .   reason - (output) result of the stopping test
    874: -   ctx    - optional context, as set by PEPSetStoppingTestFunction()

    876:    Note:
    877:    Normal usage is to first call the default routine PEPStoppingBasic() and then
    878:    set reason to PEP_CONVERGED_USER if some user-defined conditions have been
    879:    met. To let the eigensolver continue iterating, the result must be left as
    880:    PEP_CONVERGED_ITERATING.

    882:    Level: advanced

    884: .seealso: PEPSetStoppingTest(), PEPStoppingBasic()
    885: @*/
    886: PetscErrorCode PEPSetStoppingTestFunction(PEP pep,PetscErrorCode (*func)(PEP,PetscInt,PetscInt,PetscInt,PetscInt,PEPConvergedReason*,void*),void* ctx,PetscErrorCode (*destroy)(void*))
    887: {
    889:   if (pep->stoppingdestroy) (*pep->stoppingdestroy)(pep->stoppingctx);
    890:   pep->stoppinguser    = func;
    891:   pep->stoppingdestroy = destroy;
    892:   pep->stoppingctx     = ctx;
    893:   if (func == PEPStoppingBasic) pep->stop = PEP_STOP_BASIC;
    894:   else {
    895:     pep->stop     = PEP_STOP_USER;
    896:     pep->stopping = pep->stoppinguser;
    897:   }
    898:   PetscFunctionReturn(0);
    899: }

    901: /*@
    902:    PEPSetStoppingTest - Specifies how to decide the termination of the outer
    903:    loop of the eigensolver.

    905:    Logically Collective on pep

    907:    Input Parameters:
    908: +  pep  - eigensolver context obtained from PEPCreate()
    909: -  stop - the type of stopping test

    911:    Options Database Keys:
    912: +  -pep_stop_basic - Sets the default stopping test
    913: -  -pep_stop_user  - Selects the user-defined stopping test

    915:    Note:
    916:    The parameter 'stop' can have one of these values
    917: +     PEP_STOP_BASIC - default stopping test
    918: -     PEP_STOP_USER  - function set by PEPSetStoppingTestFunction()

    920:    Level: advanced

    922: .seealso: PEPGetStoppingTest(), PEPSetStoppingTestFunction(), PEPSetConvergenceTest(), PEPStop
    923: @*/
    924: PetscErrorCode PEPSetStoppingTest(PEP pep,PEPStop stop)
    925: {
    928:   switch (stop) {
    929:     case PEP_STOP_BASIC: pep->stopping = PEPStoppingBasic; break;
    930:     case PEP_STOP_USER:
    932:       pep->stopping = pep->stoppinguser;
    933:       break;
    934:     default:
    935:       SETERRQ(PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_OUTOFRANGE,"Invalid 'stop' value");
    936:   }
    937:   pep->stop = stop;
    938:   PetscFunctionReturn(0);
    939: }

    941: /*@
    942:    PEPGetStoppingTest - Gets the method used to decide the termination of the outer
    943:    loop of the eigensolver.

    945:    Not Collective

    947:    Input Parameters:
    948: .  pep   - eigensolver context obtained from PEPCreate()

    950:    Output Parameters:
    951: .  stop  - the type of stopping test

    953:    Level: advanced

    955: .seealso: PEPSetStoppingTest(), PEPStop
    956: @*/
    957: PetscErrorCode PEPGetStoppingTest(PEP pep,PEPStop *stop)
    958: {
    961:   *stop = pep->stop;
    962:   PetscFunctionReturn(0);
    963: }

    965: /*@
    966:    PEPSetScale - Specifies the scaling strategy to be used.

    968:    Logically Collective on pep

    970:    Input Parameters:
    971: +  pep    - the eigensolver context
    972: .  scale  - scaling strategy
    973: .  alpha  - the scaling factor used in the scalar strategy
    974: .  Dl     - the left diagonal matrix of the diagonal scaling algorithm
    975: .  Dr     - the right diagonal matrix of the diagonal scaling algorithm
    976: .  its    - number of iterations of the diagonal scaling algorithm
    977: -  lambda - approximation to wanted eigenvalues (modulus)

    979:    Options Database Keys:
    980: +  -pep_scale <type> - scaling type, one of <none,scalar,diagonal,both>
    981: .  -pep_scale_factor <alpha> - the scaling factor
    982: .  -pep_scale_its <its> - number of iterations
    983: -  -pep_scale_lambda <lambda> - approximation to eigenvalues

    985:    Notes:
    986:    There are two non-exclusive scaling strategies, scalar and diagonal.

    988:    In the scalar strategy, scaling is applied to the eigenvalue, that is,
    989:    mu = lambda/alpha is the new eigenvalue and all matrices are scaled
    990:    accordingly. After solving the scaled problem, the original lambda is
    991:    recovered. Parameter 'alpha' must be positive. Use PETSC_DEFAULT to let
    992:    the solver compute a reasonable scaling factor.

    994:    In the diagonal strategy, the solver works implicitly with matrix Dl*A*Dr,
    995:    where Dl and Dr are appropriate diagonal matrices. This improves the accuracy
    996:    of the computed results in some cases. The user may provide the Dr and Dl
    997:    matrices represented as Vec objects storing diagonal elements. If not
    998:    provided, these matrices are computed internally. This option requires
    999:    that the polynomial coefficient matrices are of MATAIJ type.
    1000:    The parameter 'its' is the number of iterations performed by the method.
    1001:    Parameter 'lambda' must be positive. Use PETSC_DEFAULT or set lambda = 1.0 if
    1002:    no information about eigenvalues is available.

    1004:    Level: intermediate

    1006: .seealso: PEPGetScale()
    1007: @*/
    1008: PetscErrorCode PEPSetScale(PEP pep,PEPScale scale,PetscReal alpha,Vec Dl,Vec Dr,PetscInt its,PetscReal lambda)
    1009: {
    1012:   pep->scale = scale;
    1013:   if (scale==PEP_SCALE_SCALAR || scale==PEP_SCALE_BOTH) {
    1015:     if (alpha == PETSC_DEFAULT || alpha == PETSC_DECIDE) {
    1016:       pep->sfactor = 0.0;
    1017:       pep->sfactor_set = PETSC_FALSE;
    1018:     } else {
    1020:       pep->sfactor = alpha;
    1021:       pep->sfactor_set = PETSC_TRUE;
    1022:     }
    1023:   }
    1024:   if (scale==PEP_SCALE_DIAGONAL || scale==PEP_SCALE_BOTH) {
    1025:     if (Dl) {
    1028:       PetscObjectReference((PetscObject)Dl);
    1029:       VecDestroy(&pep->Dl);
    1030:       pep->Dl = Dl;
    1031:     }
    1032:     if (Dr) {
    1035:       PetscObjectReference((PetscObject)Dr);
    1036:       VecDestroy(&pep->Dr);
    1037:       pep->Dr = Dr;
    1038:     }
    1041:     if (its==PETSC_DECIDE || its==PETSC_DEFAULT) pep->sits = 5;
    1042:     else pep->sits = its;
    1043:     if (lambda==PETSC_DECIDE || lambda==PETSC_DEFAULT) pep->slambda = 1.0;
    1044:     else {
    1046:       pep->slambda = lambda;
    1047:     }
    1048:   }
    1049:   pep->state = PEP_STATE_INITIAL;
    1050:   PetscFunctionReturn(0);
    1051: }

    1053: /*@C
    1054:    PEPGetScale - Gets the scaling strategy used by the PEP object, and the
    1055:    associated parameters.

    1057:    Not Collectiv, but vectors are shared by all processors that share the PEP

    1059:    Input Parameter:
    1060: .  pep - the eigensolver context

    1062:    Output Parameters:
    1063: +  scale  - scaling strategy
    1064: .  alpha  - the scaling factor used in the scalar strategy
    1065: .  Dl     - the left diagonal matrix of the diagonal scaling algorithm
    1066: .  Dr     - the right diagonal matrix of the diagonal scaling algorithm
    1067: .  its    - number of iterations of the diagonal scaling algorithm
    1068: -  lambda - approximation to wanted eigenvalues (modulus)

    1070:    Level: intermediate

    1072:    Note:
    1073:    The user can specify NULL for any parameter that is not needed.

    1075:    If Dl or Dr were not set by the user, then the ones computed internally are
    1076:    returned (or a null pointer if called before PEPSetUp).

    1078: .seealso: PEPSetScale(), PEPSetUp()
    1079: @*/
    1080: PetscErrorCode PEPGetScale(PEP pep,PEPScale *scale,PetscReal *alpha,Vec *Dl,Vec *Dr,PetscInt *its,PetscReal *lambda)
    1081: {
    1083:   if (scale)  *scale  = pep->scale;
    1084:   if (alpha)  *alpha  = pep->sfactor;
    1085:   if (Dl)     *Dl     = pep->Dl;
    1086:   if (Dr)     *Dr     = pep->Dr;
    1087:   if (its)    *its    = pep->sits;
    1088:   if (lambda) *lambda = pep->slambda;
    1089:   PetscFunctionReturn(0);
    1090: }

    1092: /*@
    1093:    PEPSetExtract - Specifies the extraction strategy to be used.

    1095:    Logically Collective on pep

    1097:    Input Parameters:
    1098: +  pep     - the eigensolver context
    1099: -  extract - extraction strategy

    1101:    Options Database Keys:
    1102: .  -pep_extract <type> - extraction type, one of <none,norm,residual,structured>

    1104:    Level: intermediate

    1106: .seealso: PEPGetExtract()
    1107: @*/
    1108: PetscErrorCode PEPSetExtract(PEP pep,PEPExtract extract)
    1109: {
    1112:   pep->extract = extract;
    1113:   PetscFunctionReturn(0);
    1114: }

    1116: /*@
    1117:    PEPGetExtract - Gets the extraction strategy used by the PEP object.

    1119:    Not Collective

    1121:    Input Parameter:
    1122: .  pep - the eigensolver context

    1124:    Output Parameter:
    1125: .  extract - extraction strategy

    1127:    Level: intermediate

    1129: .seealso: PEPSetExtract(), PEPExtract
    1130: @*/
    1131: PetscErrorCode PEPGetExtract(PEP pep,PEPExtract *extract)
    1132: {
    1135:   *extract = pep->extract;
    1136:   PetscFunctionReturn(0);
    1137: }

    1139: /*@
    1140:    PEPSetRefine - Specifies the refinement type (and options) to be used
    1141:    after the solve.

    1143:    Logically Collective on pep

    1145:    Input Parameters:
    1146: +  pep    - the polynomial eigensolver context
    1147: .  refine - refinement type
    1148: .  npart  - number of partitions of the communicator
    1149: .  tol    - the convergence tolerance
    1150: .  its    - maximum number of refinement iterations
    1151: -  scheme - which scheme to be used for solving the involved linear systems

    1153:    Options Database Keys:
    1154: +  -pep_refine <type> - refinement type, one of <none,simple,multiple>
    1155: .  -pep_refine_partitions <n> - the number of partitions
    1156: .  -pep_refine_tol <tol> - the tolerance
    1157: .  -pep_refine_its <its> - number of iterations
    1158: -  -pep_refine_scheme - to set the scheme for the linear solves

    1160:    Notes:
    1161:    By default, iterative refinement is disabled, since it may be very
    1162:    costly. There are two possible refinement strategies, simple and multiple.
    1163:    The simple approach performs iterative refinement on each of the
    1164:    converged eigenpairs individually, whereas the multiple strategy works
    1165:    with the invariant pair as a whole, refining all eigenpairs simultaneously.
    1166:    The latter may be required for the case of multiple eigenvalues.

    1168:    In some cases, especially when using direct solvers within the
    1169:    iterative refinement method, it may be helpful for improved scalability
    1170:    to split the communicator in several partitions. The npart parameter
    1171:    indicates how many partitions to use (defaults to 1).

    1173:    The tol and its parameters specify the stopping criterion. In the simple
    1174:    method, refinement continues until the residual of each eigenpair is
    1175:    below the tolerance (tol defaults to the PEP tol, but may be set to a
    1176:    different value). In contrast, the multiple method simply performs its
    1177:    refinement iterations (just one by default).

    1179:    The scheme argument is used to change the way in which linear systems are
    1180:    solved. Possible choices are explicit, mixed block elimination (MBE),
    1181:    and Schur complement.

    1183:    Level: intermediate

    1185: .seealso: PEPGetRefine()
    1186: @*/
    1187: PetscErrorCode PEPSetRefine(PEP pep,PEPRefine refine,PetscInt npart,PetscReal tol,PetscInt its,PEPRefineScheme scheme)
    1188: {
    1189:   PetscMPIInt    size;

    1197:   pep->refine = refine;
    1198:   if (refine) {  /* process parameters only if not REFINE_NONE */
    1199:     if (npart!=pep->npart) {
    1200:       PetscSubcommDestroy(&pep->refinesubc);
    1201:       KSPDestroy(&pep->refineksp);
    1202:     }
    1203:     if (npart == PETSC_DEFAULT || npart == PETSC_DECIDE) {
    1204:       pep->npart = 1;
    1205:     } else {
    1206:       MPI_Comm_size(PetscObjectComm((PetscObject)pep),&size);
    1208:       pep->npart = npart;
    1209:     }
    1210:     if (tol == PETSC_DEFAULT || tol == PETSC_DECIDE) {
    1211:       pep->rtol = PETSC_DEFAULT;
    1212:     } else {
    1214:       pep->rtol = tol;
    1215:     }
    1216:     if (its==PETSC_DECIDE || its==PETSC_DEFAULT) {
    1217:       pep->rits = PETSC_DEFAULT;
    1218:     } else {
    1220:       pep->rits = its;
    1221:     }
    1222:     pep->scheme = scheme;
    1223:   }
    1224:   pep->state = PEP_STATE_INITIAL;
    1225:   PetscFunctionReturn(0);
    1226: }

    1228: /*@C
    1229:    PEPGetRefine - Gets the refinement strategy used by the PEP object, and the
    1230:    associated parameters.

    1232:    Not Collective

    1234:    Input Parameter:
    1235: .  pep - the polynomial eigensolver context

    1237:    Output Parameters:
    1238: +  refine - refinement type
    1239: .  npart  - number of partitions of the communicator
    1240: .  tol    - the convergence tolerance
    1241: .  its    - maximum number of refinement iterations
    1242: -  scheme - the scheme used for solving linear systems

    1244:    Level: intermediate

    1246:    Note:
    1247:    The user can specify NULL for any parameter that is not needed.

    1249: .seealso: PEPSetRefine()
    1250: @*/
    1251: PetscErrorCode PEPGetRefine(PEP pep,PEPRefine *refine,PetscInt *npart,PetscReal *tol,PetscInt *its,PEPRefineScheme *scheme)
    1252: {
    1254:   if (refine) *refine = pep->refine;
    1255:   if (npart)  *npart  = pep->npart;
    1256:   if (tol)    *tol    = pep->rtol;
    1257:   if (its)    *its    = pep->rits;
    1258:   if (scheme) *scheme = pep->scheme;
    1259:   PetscFunctionReturn(0);
    1260: }

    1262: /*@C
    1263:    PEPSetOptionsPrefix - Sets the prefix used for searching for all
    1264:    PEP options in the database.

    1266:    Logically Collective on pep

    1268:    Input Parameters:
    1269: +  pep - the polynomial eigensolver context
    1270: -  prefix - the prefix string to prepend to all PEP option requests

    1272:    Notes:
    1273:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    1274:    The first character of all runtime options is AUTOMATICALLY the
    1275:    hyphen.

    1277:    For example, to distinguish between the runtime options for two
    1278:    different PEP contexts, one could call
    1279: .vb
    1280:       PEPSetOptionsPrefix(pep1,"qeig1_")
    1281:       PEPSetOptionsPrefix(pep2,"qeig2_")
    1282: .ve

    1284:    Level: advanced

    1286: .seealso: PEPAppendOptionsPrefix(), PEPGetOptionsPrefix()
    1287: @*/
    1288: PetscErrorCode PEPSetOptionsPrefix(PEP pep,const char *prefix)
    1289: {
    1291:   if (!pep->st) PEPGetST(pep,&pep->st);
    1292:   STSetOptionsPrefix(pep->st,prefix);
    1293:   if (!pep->V) PEPGetBV(pep,&pep->V);
    1294:   BVSetOptionsPrefix(pep->V,prefix);
    1295:   if (!pep->ds) PEPGetDS(pep,&pep->ds);
    1296:   DSSetOptionsPrefix(pep->ds,prefix);
    1297:   if (!pep->rg) PEPGetRG(pep,&pep->rg);
    1298:   RGSetOptionsPrefix(pep->rg,prefix);
    1299:   PetscObjectSetOptionsPrefix((PetscObject)pep,prefix);
    1300:   PetscFunctionReturn(0);
    1301: }

    1303: /*@C
    1304:    PEPAppendOptionsPrefix - Appends to the prefix used for searching for all
    1305:    PEP options in the database.

    1307:    Logically Collective on pep

    1309:    Input Parameters:
    1310: +  pep - the polynomial eigensolver context
    1311: -  prefix - the prefix string to prepend to all PEP option requests

    1313:    Notes:
    1314:    A hyphen (-) must NOT be given at the beginning of the prefix name.
    1315:    The first character of all runtime options is AUTOMATICALLY the hyphen.

    1317:    Level: advanced

    1319: .seealso: PEPSetOptionsPrefix(), PEPGetOptionsPrefix()
    1320: @*/
    1321: PetscErrorCode PEPAppendOptionsPrefix(PEP pep,const char *prefix)
    1322: {
    1324:   if (!pep->st) PEPGetST(pep,&pep->st);
    1325:   STAppendOptionsPrefix(pep->st,prefix);
    1326:   if (!pep->V) PEPGetBV(pep,&pep->V);
    1327:   BVAppendOptionsPrefix(pep->V,prefix);
    1328:   if (!pep->ds) PEPGetDS(pep,&pep->ds);
    1329:   DSAppendOptionsPrefix(pep->ds,prefix);
    1330:   if (!pep->rg) PEPGetRG(pep,&pep->rg);
    1331:   RGAppendOptionsPrefix(pep->rg,prefix);
    1332:   PetscObjectAppendOptionsPrefix((PetscObject)pep,prefix);
    1333:   PetscFunctionReturn(0);
    1334: }

    1336: /*@C
    1337:    PEPGetOptionsPrefix - Gets the prefix used for searching for all
    1338:    PEP options in the database.

    1340:    Not Collective

    1342:    Input Parameters:
    1343: .  pep - the polynomial eigensolver context

    1345:    Output Parameters:
    1346: .  prefix - pointer to the prefix string used is returned

    1348:    Note:
    1349:    On the Fortran side, the user should pass in a string 'prefix' of
    1350:    sufficient length to hold the prefix.

    1352:    Level: advanced

    1354: .seealso: PEPSetOptionsPrefix(), PEPAppendOptionsPrefix()
    1355: @*/
    1356: PetscErrorCode PEPGetOptionsPrefix(PEP pep,const char *prefix[])
    1357: {
    1360:   PetscObjectGetOptionsPrefix((PetscObject)pep,prefix);
    1361:   PetscFunctionReturn(0);
    1362: }