Date: 2026-01-20T11:35:10+00:00

Actual source code: pepbasic.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:    Basic PEP routines
     12: */

     14: #include <slepc/private/pepimpl.h>

     16: /* Logging support */
     17: PetscClassId      PEP_CLASSID = 0;
     18: PetscLogEvent     PEP_SetUp = 0,PEP_Solve = 0,PEP_Refine = 0,PEP_CISS_SVD = 0;

     20: /* List of registered PEP routines */
     21: PetscFunctionList PEPList = NULL;
     22: PetscBool         PEPRegisterAllCalled = PETSC_FALSE;

     24: /* List of registered PEP monitors */
     25: PetscFunctionList PEPMonitorList              = NULL;
     26: PetscFunctionList PEPMonitorCreateList        = NULL;
     27: PetscFunctionList PEPMonitorDestroyList       = NULL;
     28: PetscBool         PEPMonitorRegisterAllCalled = PETSC_FALSE;

     30: /*@
     31:    PEPCreate - Creates the `PEP` context.

     33:    Collective

     35:    Input Parameter:
     36: .  comm - MPI communicator

     38:    Output Parameter:
     39: .  outpep - location to put the `PEP` context

     41:    Note:
     42:    The default `PEP` type is `PEPTOAR`.

     44:    Level: beginner

     46: .seealso: [](ch:pep), `PEPSetUp()`, `PEPSolve()`, `PEPDestroy()`, `PEP`
     47: @*/
     48: PetscErrorCode PEPCreate(MPI_Comm comm,PEP *outpep)
     49: {
     50:   PEP            pep;

     52:   PetscFunctionBegin;
     53:   PetscAssertPointer(outpep,2);
     54:   PetscCall(PEPInitializePackage());
     55:   PetscCall(SlepcHeaderCreate(pep,PEP_CLASSID,"PEP","Polynomial Eigenvalue Problem","PEP",comm,PEPDestroy,PEPView));

     57:   pep->max_it          = PETSC_DETERMINE;
     58:   pep->nev             = 1;
     59:   pep->ncv             = PETSC_DETERMINE;
     60:   pep->mpd             = PETSC_DETERMINE;
     61:   pep->nini            = 0;
     62:   pep->target          = 0.0;
     63:   pep->tol             = PETSC_DETERMINE;
     64:   pep->conv            = PEP_CONV_REL;
     65:   pep->stop            = PEP_STOP_BASIC;
     66:   pep->which           = (PEPWhich)0;
     67:   pep->basis           = PEP_BASIS_MONOMIAL;
     68:   pep->problem_type    = (PEPProblemType)0;
     69:   pep->scale           = PEP_SCALE_NONE;
     70:   pep->sfactor         = 1.0;
     71:   pep->dsfactor        = 1.0;
     72:   pep->sits            = 5;
     73:   pep->slambda         = 1.0;
     74:   pep->refine          = PEP_REFINE_NONE;
     75:   pep->npart           = 1;
     76:   pep->rtol            = PETSC_DETERMINE;
     77:   pep->rits            = PETSC_DETERMINE;
     78:   pep->scheme          = (PEPRefineScheme)0;
     79:   pep->extract         = (PEPExtract)0;
     80:   pep->trackall        = PETSC_FALSE;

     82:   pep->converged       = PEPConvergedRelative;
     83:   pep->convergeduser   = NULL;
     84:   pep->convergeddestroy= NULL;
     85:   pep->stopping        = PEPStoppingBasic;
     86:   pep->stoppinguser    = NULL;
     87:   pep->stoppingdestroy = NULL;
     88:   pep->convergedctx    = NULL;
     89:   pep->stoppingctx     = NULL;
     90:   pep->numbermonitors  = 0;

     92:   pep->st              = NULL;
     93:   pep->ds              = NULL;
     94:   pep->V               = NULL;
     95:   pep->rg              = NULL;
     96:   pep->A               = NULL;
     97:   pep->nmat            = 0;
     98:   pep->Dl              = NULL;
     99:   pep->Dr              = NULL;
    100:   pep->IS              = NULL;
    101:   pep->eigr            = NULL;
    102:   pep->eigi            = NULL;
    103:   pep->errest          = NULL;
    104:   pep->perm            = NULL;
    105:   pep->pbc             = NULL;
    106:   pep->solvematcoeffs  = NULL;
    107:   pep->nwork           = 0;
    108:   pep->work            = NULL;
    109:   pep->refineksp       = NULL;
    110:   pep->refinesubc      = NULL;
    111:   pep->data            = NULL;

    113:   pep->state           = PEP_STATE_INITIAL;
    114:   pep->nconv           = 0;
    115:   pep->its             = 0;
    116:   pep->n               = 0;
    117:   pep->nloc            = 0;
    118:   pep->nrma            = NULL;
    119:   pep->sfactor_set     = PETSC_FALSE;
    120:   pep->lineariz        = PETSC_FALSE;
    121:   pep->reason          = PEP_CONVERGED_ITERATING;

    123:   PetscCall(PetscNew(&pep->sc));
    124:   *outpep = pep;
    125:   PetscFunctionReturn(PETSC_SUCCESS);
    126: }

    128: /*@
    129:    PEPSetType - Selects the particular solver to be used in the `PEP` object.

    131:    Logically Collective

    133:    Input Parameters:
    134: +  pep  - the polynomial eigensolver context
    135: -  type - a known method

    137:    Options Database Key:
    138: .  -pep_type \<type\> - sets the method; use `-help` for a list of available methods

    140:    Notes:
    141:    See `PEPType` for available methods. The default is `PEPTOAR`.

    143:    Normally, it is best to use the `PEPSetFromOptions()` command and
    144:    then set the `PEP` type from the options database rather than by using
    145:    this routine.  Using the options database provides the user with
    146:    maximum flexibility in evaluating the different available methods.
    147:    The `PEPSetType()` routine is provided for those situations where it
    148:    is necessary to set the iterative solver independently of the command
    149:    line or options database.

    151:    Level: intermediate

    153: .seealso: [](ch:pep), `PEPType`
    154: @*/
    155: PetscErrorCode PEPSetType(PEP pep,PEPType type)
    156: {
    157:   PetscErrorCode (*r)(PEP);
    158:   PetscBool      match;

    160:   PetscFunctionBegin;
    162:   PetscAssertPointer(type,2);

    164:   PetscCall(PetscObjectTypeCompare((PetscObject)pep,type,&match));
    165:   if (match) PetscFunctionReturn(PETSC_SUCCESS);

    167:   PetscCall(PetscFunctionListFind(PEPList,type,&r));
    168:   PetscCheck(r,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_UNKNOWN_TYPE,"Unknown PEP type given: %s",type);

    170:   PetscTryTypeMethod(pep,destroy);
    171:   PetscCall(PetscMemzero(pep->ops,sizeof(struct _PEPOps)));

    173:   pep->state = PEP_STATE_INITIAL;
    174:   PetscCall(PetscObjectChangeTypeName((PetscObject)pep,type));
    175:   PetscCall((*r)(pep));
    176:   PetscFunctionReturn(PETSC_SUCCESS);
    177: }

    179: /*@
    180:    PEPGetType - Gets the `PEP` type as a string from the `PEP` object.

    182:    Not Collective

    184:    Input Parameter:
    185: .  pep - the polynomial eigensolver context

    187:    Output Parameter:
    188: .  type - name of `PEP` method

    190:    Level: intermediate

    192: .seealso: [](ch:pep), `PEPSetType()`
    193: @*/
    194: PetscErrorCode PEPGetType(PEP pep,PEPType *type)
    195: {
    196:   PetscFunctionBegin;
    198:   PetscAssertPointer(type,2);
    199:   *type = ((PetscObject)pep)->type_name;
    200:   PetscFunctionReturn(PETSC_SUCCESS);
    201: }

    203: /*@C
    204:    PEPRegister - Adds a method to the polynomial eigenproblem solver package.

    206:    Not Collective

    208:    Input Parameters:
    209: +  name     - name of a new user-defined solver
    210: -  function - routine to create the solver context

    212:    Note:
    213:    `PEPRegister()` may be called multiple times to add several user-defined solvers.

    215:    Example Usage:
    216: .vb
    217:    PEPRegister("my_solver",MySolverCreate);
    218: .ve

    220:    Then, your solver can be chosen with the procedural interface via
    221: .vb
    222:    PEPSetType(pep,"my_solver")
    223: .ve
    224:    or at runtime via the option `-pep_type my_solver`.

    226:    Level: advanced

    228: .seealso: [](ch:pep), `PEPRegisterAll()`
    229: @*/
    230: PetscErrorCode PEPRegister(const char *name,PetscErrorCode (*function)(PEP))
    231: {
    232:   PetscFunctionBegin;
    233:   PetscCall(PEPInitializePackage());
    234:   PetscCall(PetscFunctionListAdd(&PEPList,name,function));
    235:   PetscFunctionReturn(PETSC_SUCCESS);
    236: }

    238: /*@C
    239:    PEPMonitorRegister - Registers a `PEP` monitor routine that may be accessed with
    240:    `PEPMonitorSetFromOptions()`.

    242:    Not Collective

    244:    Input Parameters:
    245: +  name    - name of a new monitor routine
    246: .  vtype   - a `PetscViewerType` for the output
    247: .  format  - a `PetscViewerFormat` for the output
    248: .  monitor - monitor routine, see `PEPMonitorRegisterFn`
    249: .  create  - creation routine, or `NULL`
    250: -  destroy - destruction routine, or `NULL`

    252:    Notes:
    253:    `PEPMonitorRegister()` may be called multiple times to add several user-defined monitors.

    255:    The calling sequence for the given function matches the calling sequence of `PEPMonitorFn`
    256:    functions passed to `PEPMonitorSet()` with the additional requirement that its final argument
    257:    be a `PetscViewerAndFormat`.

    259:    Example Usage:
    260: .vb
    261:    PEPMonitorRegister("my_monitor",PETSCVIEWERASCII,PETSC_VIEWER_ASCII_INFO_DETAIL,MyMonitor,NULL,NULL);
    262: .ve

    264:    Then, your monitor can be chosen with the procedural interface via
    265: .vb
    266:    PEPMonitorSetFromOptions(pep,"-pep_monitor_my_monitor","my_monitor",NULL);
    267: .ve
    268:    or at runtime via the option `-pep_monitor_my_monitor`.

    270:    Level: advanced

    272: .seealso: [](ch:pep), `PEPMonitorSet()`, `PEPMonitorRegisterAll()`, `PEPMonitorSetFromOptions()`
    273: @*/
    274: PetscErrorCode PEPMonitorRegister(const char name[],PetscViewerType vtype,PetscViewerFormat format,PEPMonitorRegisterFn *monitor,PEPMonitorRegisterCreateFn *create,PEPMonitorRegisterDestroyFn *destroy)
    275: {
    276:   char           key[PETSC_MAX_PATH_LEN];

    278:   PetscFunctionBegin;
    279:   PetscCall(PEPInitializePackage());
    280:   PetscCall(SlepcMonitorMakeKey_Internal(name,vtype,format,key));
    281:   PetscCall(PetscFunctionListAdd(&PEPMonitorList,key,monitor));
    282:   if (create)  PetscCall(PetscFunctionListAdd(&PEPMonitorCreateList,key,create));
    283:   if (destroy) PetscCall(PetscFunctionListAdd(&PEPMonitorDestroyList,key,destroy));
    284:   PetscFunctionReturn(PETSC_SUCCESS);
    285: }

    287: /*@
    288:    PEPReset - Resets the `PEP` context to the initial state (prior to setup)
    289:    and destroys any allocated `Vec`s and `Mat`s.

    291:    Collective

    293:    Input Parameter:
    294: .  pep - the polynomial eigensolver context

    296:    Level: advanced

    298: .seealso: [](ch:pep), `PEPDestroy()`
    299: @*/
    300: PetscErrorCode PEPReset(PEP pep)
    301: {
    302:   PetscFunctionBegin;
    304:   if (!pep) PetscFunctionReturn(PETSC_SUCCESS);
    305:   PetscTryTypeMethod(pep,reset);
    306:   if (pep->st) PetscCall(STReset(pep->st));
    307:   if (pep->refineksp) PetscCall(KSPReset(pep->refineksp));
    308:   if (pep->nmat) {
    309:     PetscCall(MatDestroyMatrices(pep->nmat,&pep->A));
    310:     PetscCall(PetscFree2(pep->pbc,pep->nrma));
    311:     PetscCall(PetscFree(pep->solvematcoeffs));
    312:     pep->nmat = 0;
    313:   }
    314:   PetscCall(VecDestroy(&pep->Dl));
    315:   PetscCall(VecDestroy(&pep->Dr));
    316:   PetscCall(BVDestroy(&pep->V));
    317:   PetscCall(VecDestroyVecs(pep->nwork,&pep->work));
    318:   pep->nwork = 0;
    319:   pep->state = PEP_STATE_INITIAL;
    320:   PetscFunctionReturn(PETSC_SUCCESS);
    321: }

    323: /*@
    324:    PEPDestroy - Destroys the `PEP` context.

    326:    Collective

    328:    Input Parameter:
    329: .  pep - the polynomial eigensolver context

    331:    Level: beginner

    333: .seealso: [](ch:pep), `PEPCreate()`, `PEPSetUp()`, `PEPSolve()`
    334: @*/
    335: PetscErrorCode PEPDestroy(PEP *pep)
    336: {
    337:   PetscFunctionBegin;
    338:   if (!*pep) PetscFunctionReturn(PETSC_SUCCESS);
    340:   if (--((PetscObject)*pep)->refct > 0) { *pep = NULL; PetscFunctionReturn(PETSC_SUCCESS); }
    341:   PetscCall(PEPReset(*pep));
    342:   PetscTryTypeMethod(*pep,destroy);
    343:   if ((*pep)->eigr) PetscCall(PetscFree4((*pep)->eigr,(*pep)->eigi,(*pep)->errest,(*pep)->perm));
    344:   PetscCall(STDestroy(&(*pep)->st));
    345:   PetscCall(RGDestroy(&(*pep)->rg));
    346:   PetscCall(DSDestroy(&(*pep)->ds));
    347:   PetscCall(KSPDestroy(&(*pep)->refineksp));
    348:   PetscCall(PetscSubcommDestroy(&(*pep)->refinesubc));
    349:   PetscCall(PetscFree((*pep)->sc));
    350:   /* just in case the initial vectors have not been used */
    351:   PetscCall(SlepcBasisDestroy_Private(&(*pep)->nini,&(*pep)->IS));
    352:   if ((*pep)->convergeddestroy) PetscCall((*(*pep)->convergeddestroy)(&(*pep)->convergedctx));
    353:   if ((*pep)->stoppingdestroy) PetscCall((*(*pep)->stoppingdestroy)(&(*pep)->stoppingctx));
    354:   PetscCall(PEPMonitorCancel(*pep));
    355:   PetscCall(PetscHeaderDestroy(pep));
    356:   PetscFunctionReturn(PETSC_SUCCESS);
    357: }

    359: /*@
    360:    PEPSetBV - Associates a basis vectors object to the polynomial eigensolver.

    362:    Collective

    364:    Input Parameters:
    365: +  pep - the polynomial eigensolver context
    366: -  bv  - the basis vectors object

    368:    Note:
    369:    Use `PEPGetBV()` to retrieve the basis vectors context (for example,
    370:    to free it at the end of the computations).

    372:    Level: advanced

    374: .seealso: [](ch:pep), `PEPGetBV()`
    375: @*/
    376: PetscErrorCode PEPSetBV(PEP pep,BV bv)
    377: {
    378:   PetscFunctionBegin;
    381:   PetscCheckSameComm(pep,1,bv,2);
    382:   PetscCall(PetscObjectReference((PetscObject)bv));
    383:   PetscCall(BVDestroy(&pep->V));
    384:   pep->V = bv;
    385:   PetscFunctionReturn(PETSC_SUCCESS);
    386: }

    388: /*@
    389:    PEPGetBV - Obtain the basis vectors object associated to the polynomial
    390:    eigensolver object.

    392:    Not Collective

    394:    Input Parameter:
    395: .  pep - the polynomial eigensolver context

    397:    Output Parameter:
    398: .  bv - basis vectors context

    400:    Level: advanced

    402: .seealso: [](ch:pep), `PEPSetBV()`
    403: @*/
    404: PetscErrorCode PEPGetBV(PEP pep,BV *bv)
    405: {
    406:   PetscFunctionBegin;
    408:   PetscAssertPointer(bv,2);
    409:   if (!pep->V) {
    410:     PetscCall(BVCreate(PetscObjectComm((PetscObject)pep),&pep->V));
    411:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)pep->V,(PetscObject)pep,0));
    412:     PetscCall(PetscObjectSetOptions((PetscObject)pep->V,((PetscObject)pep)->options));
    413:   }
    414:   *bv = pep->V;
    415:   PetscFunctionReturn(PETSC_SUCCESS);
    416: }

    418: /*@
    419:    PEPSetRG - Associates a region object to the polynomial eigensolver.

    421:    Collective

    423:    Input Parameters:
    424: +  pep - the polynomial eigensolver context
    425: -  rg  - the region object

    427:    Note:
    428:    Use `PEPGetRG()` to retrieve the region context (for example,
    429:    to free it at the end of the computations).

    431:    Level: advanced

    433: .seealso: [](ch:pep), `PEPGetRG()`
    434: @*/
    435: PetscErrorCode PEPSetRG(PEP pep,RG rg)
    436: {
    437:   PetscFunctionBegin;
    439:   if (rg) {
    441:     PetscCheckSameComm(pep,1,rg,2);
    442:   }
    443:   PetscCall(PetscObjectReference((PetscObject)rg));
    444:   PetscCall(RGDestroy(&pep->rg));
    445:   pep->rg = rg;
    446:   PetscFunctionReturn(PETSC_SUCCESS);
    447: }

    449: /*@
    450:    PEPGetRG - Obtain the region object associated to the
    451:    polynomial eigensolver object.

    453:    Not Collective

    455:    Input Parameter:
    456: .  pep - the polynomial eigensolver context

    458:    Output Parameter:
    459: .  rg - region context

    461:    Level: advanced

    463: .seealso: [](ch:pep), `PEPSetRG()`
    464: @*/
    465: PetscErrorCode PEPGetRG(PEP pep,RG *rg)
    466: {
    467:   PetscFunctionBegin;
    469:   PetscAssertPointer(rg,2);
    470:   if (!pep->rg) {
    471:     PetscCall(RGCreate(PetscObjectComm((PetscObject)pep),&pep->rg));
    472:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)pep->rg,(PetscObject)pep,0));
    473:     PetscCall(PetscObjectSetOptions((PetscObject)pep->rg,((PetscObject)pep)->options));
    474:   }
    475:   *rg = pep->rg;
    476:   PetscFunctionReturn(PETSC_SUCCESS);
    477: }

    479: /*@
    480:    PEPSetDS - Associates a direct solver object to the polynomial eigensolver.

    482:    Collective

    484:    Input Parameters:
    485: +  pep - the polynomial eigensolver context
    486: -  ds  - the direct solver object

    488:    Note:
    489:    Use `PEPGetDS()` to retrieve the direct solver context (for example,
    490:    to free it at the end of the computations).

    492:    Level: advanced

    494: .seealso: [](ch:pep), `PEPGetDS()`
    495: @*/
    496: PetscErrorCode PEPSetDS(PEP pep,DS ds)
    497: {
    498:   PetscFunctionBegin;
    501:   PetscCheckSameComm(pep,1,ds,2);
    502:   PetscCall(PetscObjectReference((PetscObject)ds));
    503:   PetscCall(DSDestroy(&pep->ds));
    504:   pep->ds = ds;
    505:   PetscFunctionReturn(PETSC_SUCCESS);
    506: }

    508: /*@
    509:    PEPGetDS - Obtain the direct solver object associated to the
    510:    polynomial eigensolver object.

    512:    Not Collective

    514:    Input Parameter:
    515: .  pep - the polynomial eigensolver context

    517:    Output Parameter:
    518: .  ds - direct solver context

    520:    Level: advanced

    522: .seealso: [](ch:pep), `PEPSetDS()`
    523: @*/
    524: PetscErrorCode PEPGetDS(PEP pep,DS *ds)
    525: {
    526:   PetscFunctionBegin;
    528:   PetscAssertPointer(ds,2);
    529:   if (!pep->ds) {
    530:     PetscCall(DSCreate(PetscObjectComm((PetscObject)pep),&pep->ds));
    531:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)pep->ds,(PetscObject)pep,0));
    532:     PetscCall(PetscObjectSetOptions((PetscObject)pep->ds,((PetscObject)pep)->options));
    533:   }
    534:   *ds = pep->ds;
    535:   PetscFunctionReturn(PETSC_SUCCESS);
    536: }

    538: /*@
    539:    PEPSetST - Associates a spectral transformation object to the eigensolver.

    541:    Collective

    543:    Input Parameters:
    544: +  pep - the polynomial eigensolver context
    545: -  st  - the spectral transformation object

    547:    Note:
    548:    Use `PEPGetST()` to retrieve the spectral transformation context (for example,
    549:    to free it at the end of the computations).

    551:    Level: advanced

    553: .seealso: [](ch:pep), `PEPGetST()`
    554: @*/
    555: PetscErrorCode PEPSetST(PEP pep,ST st)
    556: {
    557:   PetscFunctionBegin;
    560:   PetscCheckSameComm(pep,1,st,2);
    561:   PetscCall(PetscObjectReference((PetscObject)st));
    562:   PetscCall(STDestroy(&pep->st));
    563:   pep->st = st;
    564:   PetscFunctionReturn(PETSC_SUCCESS);
    565: }

    567: /*@
    568:    PEPGetST - Obtain the spectral transformation (`ST`) object associated
    569:    to the eigensolver object.

    571:    Not Collective

    573:    Input Parameter:
    574: .  pep - the polynomial eigensolver context

    576:    Output Parameter:
    577: .  st - spectral transformation context

    579:    Level: intermediate

    581: .seealso: [](ch:pep), `PEPSetST()`
    582: @*/
    583: PetscErrorCode PEPGetST(PEP pep,ST *st)
    584: {
    585:   PetscFunctionBegin;
    587:   PetscAssertPointer(st,2);
    588:   if (!pep->st) {
    589:     PetscCall(STCreate(PetscObjectComm((PetscObject)pep),&pep->st));
    590:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)pep->st,(PetscObject)pep,0));
    591:     PetscCall(PetscObjectSetOptions((PetscObject)pep->st,((PetscObject)pep)->options));
    592:   }
    593:   *st = pep->st;
    594:   PetscFunctionReturn(PETSC_SUCCESS);
    595: }

    597: /*@
    598:    PEPRefineGetKSP - Obtain the `KSP` object used by the eigensolver
    599:    object in the refinement phase.

    601:    Collective

    603:    Input Parameter:
    604: .  pep - the polynomial eigensolver context

    606:    Output Parameter:
    607: .  ksp - the linear solver context

    609:    Level: advanced

    611: .seealso: [](ch:pep), `PEPSetRefine()`
    612: @*/
    613: PetscErrorCode PEPRefineGetKSP(PEP pep,KSP *ksp)
    614: {
    615:   MPI_Comm       comm;

    617:   PetscFunctionBegin;
    619:   PetscAssertPointer(ksp,2);
    620:   if (!pep->refineksp) {
    621:     if (pep->npart>1) {
    622:       /* Split in subcomunicators */
    623:       PetscCall(PetscSubcommCreate(PetscObjectComm((PetscObject)pep),&pep->refinesubc));
    624:       PetscCall(PetscSubcommSetNumber(pep->refinesubc,pep->npart));
    625:       PetscCall(PetscSubcommSetType(pep->refinesubc,PETSC_SUBCOMM_CONTIGUOUS));
    626:       PetscCall(PetscSubcommGetChild(pep->refinesubc,&comm));
    627:     } else PetscCall(PetscObjectGetComm((PetscObject)pep,&comm));
    628:     PetscCall(KSPCreate(comm,&pep->refineksp));
    629:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)pep->refineksp,(PetscObject)pep,0));
    630:     PetscCall(PetscObjectSetOptions((PetscObject)pep->refineksp,((PetscObject)pep)->options));
    631:     PetscCall(KSPSetOptionsPrefix(*ksp,((PetscObject)pep)->prefix));
    632:     PetscCall(KSPAppendOptionsPrefix(*ksp,"pep_refine_"));
    633:     PetscCall(KSPSetTolerances(pep->refineksp,SlepcDefaultTol(pep->rtol),PETSC_CURRENT,PETSC_CURRENT,PETSC_CURRENT));
    634:   }
    635:   *ksp = pep->refineksp;
    636:   PetscFunctionReturn(PETSC_SUCCESS);
    637: }

    639: /*@
    640:    PEPSetTarget - Sets the value of the target.

    642:    Logically Collective

    644:    Input Parameters:
    645: +  pep    - the polynomial eigensolver context
    646: -  target - the value of the target

    648:    Options Database Key:
    649: .  -pep_target \<target\> - the value of the target

    651:    Notes:
    652:    The target is a scalar value used to determine the portion of the spectrum
    653:    of interest. It is used in combination with `PEPSetWhichEigenpairs()`.

    655:    When PETSc is built with real scalars, it is not possible to specify a
    656:    complex target.

    658:    In the case of complex scalars, a complex value can be provided in the
    659:    command line with `[+/-][realnumber][+/-]realnumberi` with no spaces, e.g.
    660:    `-pep_target 1.0+2.0i`.

    662:    Level: intermediate

    664: .seealso: [](ch:pep), `PEPGetTarget()`, `PEPSetWhichEigenpairs()`
    665: @*/
    666: PetscErrorCode PEPSetTarget(PEP pep,PetscScalar target)
    667: {
    668:   PetscFunctionBegin;
    671:   pep->target = target;
    672:   if (!pep->st) PetscCall(PEPGetST(pep,&pep->st));
    673:   PetscCall(STSetDefaultShift(pep->st,target));
    674:   PetscFunctionReturn(PETSC_SUCCESS);
    675: }

    677: /*@
    678:    PEPGetTarget - Gets the value of the target.

    680:    Not Collective

    682:    Input Parameter:
    683: .  pep - the polynomial eigensolver context

    685:    Output Parameter:
    686: .  target - the value of the target

    688:    Note:
    689:    If the target was not set by the user, then zero is returned.

    691:    Level: intermediate

    693: .seealso: [](ch:pep), `PEPSetTarget()`
    694: @*/
    695: PetscErrorCode PEPGetTarget(PEP pep,PetscScalar* target)
    696: {
    697:   PetscFunctionBegin;
    699:   PetscAssertPointer(target,2);
    700:   *target = pep->target;
    701:   PetscFunctionReturn(PETSC_SUCCESS);
    702: }

    704: /*@
    705:    PEPSetInterval - Defines the computational interval for spectrum slicing.

    707:    Logically Collective

    709:    Input Parameters:
    710: +  pep  - the polynomial eigensolver context
    711: .  inta - left end of the interval
    712: -  intb - right end of the interval

    714:    Options Database Key:
    715: .  -pep_interval <a,b> - set $[a,b]$ as the interval of interest

    717:    Notes:
    718:    Spectrum slicing is a technique employed for computing all eigenvalues of
    719:    symmetric quadratic eigenproblems in a given interval, see section [](#sec:qslice).
    720:    This function provides the interval to be considered. It must be used in
    721:    combination with `PEP_ALL`, see `PEPSetWhichEigenpairs()`. Note that in
    722:    polynomial eigenproblems spectrum slicing is implemented in `PEPSTOAR` only.

    724:    In the command-line option, two values must be provided. For an open interval,
    725:    one can give an infinite, e.g., `-pep_interval 1.0,inf` or `-pep_interval -inf,1.0`.
    726:    An open interval in the programmatic interface can be specified with
    727:    `PETSC_MAX_REAL` and -`PETSC_MAX_REAL`.

    729:    Level: intermediate

    731: .seealso: [](ch:pep), [](#sec:qslice), `PEPGetInterval()`, `PEPSetWhichEigenpairs()`, `PEPSTOAR`
    732: @*/
    733: PetscErrorCode PEPSetInterval(PEP pep,PetscReal inta,PetscReal intb)
    734: {
    735:   PetscFunctionBegin;
    739:   PetscCheck(inta<intb,PetscObjectComm((PetscObject)pep),PETSC_ERR_ARG_WRONG,"Badly defined interval, must be inta<intb");
    740:   if (pep->inta != inta || pep->intb != intb) {
    741:     pep->inta = inta;
    742:     pep->intb = intb;
    743:     pep->state = PEP_STATE_INITIAL;
    744:   }
    745:   PetscFunctionReturn(PETSC_SUCCESS);
    746: }

    748: /*@
    749:    PEPGetInterval - Gets the computational interval for spectrum slicing.

    751:    Not Collective

    753:    Input Parameter:
    754: .  pep - the polynomial eigensolver context

    756:    Output Parameters:
    757: +  inta - left end of the interval
    758: -  intb - right end of the interval

    760:    Level: intermediate

    762:    Note:
    763:    If the interval was not set by the user, then zeros are returned.

    765: .seealso: [](ch:pep), `PEPSetInterval()`
    766: @*/
    767: PetscErrorCode PEPGetInterval(PEP pep,PetscReal* inta,PetscReal* intb)
    768: {
    769:   PetscFunctionBegin;
    771:   if (inta) *inta = pep->inta;
    772:   if (intb) *intb = pep->intb;
    773:   PetscFunctionReturn(PETSC_SUCCESS);
    774: }