Date: 2021-09-20T09:44:08+00:00

Actual source code: nepdefault.c
slepc-3.15.2 2021-09-20
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2021, 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:    Simple default routines for common NEP operations
     12: */

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

     16: /*@
     17:    NEPSetWorkVecs - Sets a number of work vectors into a NEP object

     19:    Collective on nep

     21:    Input Parameters:
     22: +  nep - nonlinear eigensolver context
     23: -  nw  - number of work vectors to allocate

     25:    Developers Note:
     26:    This is SLEPC_EXTERN because it may be required by user plugin NEP
     27:    implementations.

     29:    Level: developer
     30: @*/
     31: PetscErrorCode NEPSetWorkVecs(NEP nep,PetscInt nw)
     32: {
     34:   Vec            t;

     37:   if (nep->nwork < nw) {
     38:     VecDestroyVecs(nep->nwork,&nep->work);
     39:     nep->nwork = nw;
     40:     BVGetColumn(nep->V,0,&t);
     41:     VecDuplicateVecs(t,nw,&nep->work);
     42:     BVRestoreColumn(nep->V,0,&t);
     43:     PetscLogObjectParents(nep,nw,nep->work);
     44:   }
     45:   return(0);
     46: }

     48: /*
     49:   NEPGetDefaultShift - Return the value of sigma to start the nonlinear iteration.
     50:  */
     51: PetscErrorCode NEPGetDefaultShift(NEP nep,PetscScalar *sigma)
     52: {
     55:   switch (nep->which) {
     56:     case NEP_LARGEST_MAGNITUDE:
     57:     case NEP_LARGEST_IMAGINARY:
     58:     case NEP_ALL:
     59:     case NEP_WHICH_USER:
     60:       *sigma = 1.0;   /* arbitrary value */
     61:       break;
     62:     case NEP_SMALLEST_MAGNITUDE:
     63:     case NEP_SMALLEST_IMAGINARY:
     64:       *sigma = 0.0;
     65:       break;
     66:     case NEP_LARGEST_REAL:
     67:       *sigma = PETSC_MAX_REAL;
     68:       break;
     69:     case NEP_SMALLEST_REAL:
     70:       *sigma = PETSC_MIN_REAL;
     71:       break;
     72:     case NEP_TARGET_MAGNITUDE:
     73:     case NEP_TARGET_REAL:
     74:     case NEP_TARGET_IMAGINARY:
     75:       *sigma = nep->target;
     76:       break;
     77:   }
     78:   return(0);
     79: }

     81: /*
     82:   NEPConvergedRelative - Checks convergence relative to the eigenvalue.
     83: */
     84: PetscErrorCode NEPConvergedRelative(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
     85: {
     86:   PetscReal w;

     89:   w = SlepcAbsEigenvalue(eigr,eigi);
     90:   *errest = res/w;
     91:   return(0);
     92: }

     94: /*
     95:   NEPConvergedAbsolute - Checks convergence absolutely.
     96: */
     97: PetscErrorCode NEPConvergedAbsolute(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
     98: {
    100:   *errest = res;
    101:   return(0);
    102: }

    104: /*
    105:   NEPConvergedNorm - Checks convergence relative to the matrix norms.
    106: */
    107: PetscErrorCode NEPConvergedNorm(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
    108: {
    109:   PetscScalar    s;
    110:   PetscReal      w=0.0;
    111:   PetscInt       j;
    112:   PetscBool      flg;

    116:   if (nep->fui!=NEP_USER_INTERFACE_SPLIT) {
    117:     NEPComputeFunction(nep,eigr,nep->function,nep->function);
    118:     MatHasOperation(nep->function,MATOP_NORM,&flg);
    119:     if (!flg) SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_WRONG,"The computation of backward errors requires a matrix norm operation");
    120:     MatNorm(nep->function,NORM_INFINITY,&w);
    121:   } else {
    122:     /* initialization of matrix norms */
    123:     if (!nep->nrma[0]) {
    124:       for (j=0;j<nep->nt;j++) {
    125:         MatHasOperation(nep->A[j],MATOP_NORM,&flg);
    126:         if (!flg) SETERRQ(PetscObjectComm((PetscObject)nep),PETSC_ERR_ARG_WRONG,"The convergence test related to the matrix norms requires a matrix norm operation");
    127:         MatNorm(nep->A[j],NORM_INFINITY,&nep->nrma[j]);
    128:       }
    129:     }
    130:     for (j=0;j<nep->nt;j++) {
    131:       FNEvaluateFunction(nep->f[j],eigr,&s);
    132:       w = w + nep->nrma[j]*PetscAbsScalar(s);
    133:     }
    134:   }
    135:   *errest = res/w;
    136:   return(0);
    137: }

    139: /*@C
    140:    NEPStoppingBasic - Default routine to determine whether the outer eigensolver
    141:    iteration must be stopped.

    143:    Collective on nep

    145:    Input Parameters:
    146: +  nep    - nonlinear eigensolver context obtained from NEPCreate()
    147: .  its    - current number of iterations
    148: .  max_it - maximum number of iterations
    149: .  nconv  - number of currently converged eigenpairs
    150: .  nev    - number of requested eigenpairs
    151: -  ctx    - context (not used here)

    153:    Output Parameter:
    154: .  reason - result of the stopping test

    156:    Notes:
    157:    A positive value of reason indicates that the iteration has finished successfully
    158:    (converged), and a negative value indicates an error condition (diverged). If
    159:    the iteration needs to be continued, reason must be set to NEP_CONVERGED_ITERATING
    160:    (zero).

    162:    NEPStoppingBasic() will stop if all requested eigenvalues are converged, or if
    163:    the maximum number of iterations has been reached.

    165:    Use NEPSetStoppingTest() to provide your own test instead of using this one.

    167:    Level: advanced

    169: .seealso: NEPSetStoppingTest(), NEPConvergedReason, NEPGetConvergedReason()
    170: @*/
    171: PetscErrorCode NEPStoppingBasic(NEP nep,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nev,NEPConvergedReason *reason,void *ctx)
    172: {

    176:   *reason = NEP_CONVERGED_ITERATING;
    177:   if (nconv >= nev) {
    178:     PetscInfo2(nep,"Nonlinear eigensolver finished successfully: %D eigenpairs converged at iteration %D\n",nconv,its);
    179:     *reason = NEP_CONVERGED_TOL;
    180:   } else if (its >= max_it) {
    181:     *reason = NEP_DIVERGED_ITS;
    182:     PetscInfo1(nep,"Nonlinear eigensolver iteration reached maximum number of iterations (%D)\n",its);
    183:   }
    184:   return(0);
    185: }

    187: PetscErrorCode NEPComputeVectors_Schur(NEP nep)
    188: {
    190:   Mat            Z;

    193:   DSVectors(nep->ds,DS_MAT_X,NULL,NULL);
    194:   DSGetMat(nep->ds,DS_MAT_X,&Z);
    195:   BVMultInPlace(nep->V,Z,0,nep->nconv);
    196:   MatDestroy(&Z);
    197:   BVNormalize(nep->V,nep->eigi);
    198:   return(0);
    199: }