Date: 2023-01-26T12:19:26+00:00

Actual source code: nepdefault.c
slepc-3.18.2 2023-01-26
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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:    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:    Developer Notes:
     26:    This is SLEPC_EXTERN because it may be required by user plugin NEP
     27:    implementations.

     29:    Level: developer

     31: .seealso: NEPSetUp()
     32: @*/
     33: PetscErrorCode NEPSetWorkVecs(NEP nep,PetscInt nw)
     34: {
     35:   Vec            t;

     40:   if (nep->nwork < nw) {
     41:     VecDestroyVecs(nep->nwork,&nep->work);
     42:     nep->nwork = nw;
     43:     BVGetColumn(nep->V,0,&t);
     44:     VecDuplicateVecs(t,nw,&nep->work);
     45:     BVRestoreColumn(nep->V,0,&t);
     46:   }
     47:   return 0;
     48: }

     50: /*
     51:   NEPGetDefaultShift - Return the value of sigma to start the nonlinear iteration.
     52:  */
     53: PetscErrorCode NEPGetDefaultShift(NEP nep,PetscScalar *sigma)
     54: {
     56:   switch (nep->which) {
     57:     case NEP_LARGEST_MAGNITUDE:
     58:     case NEP_LARGEST_IMAGINARY:
     59:     case NEP_ALL:
     60:     case NEP_WHICH_USER:
     61:       *sigma = 1.0;   /* arbitrary value */
     62:       break;
     63:     case NEP_SMALLEST_MAGNITUDE:
     64:     case NEP_SMALLEST_IMAGINARY:
     65:       *sigma = 0.0;
     66:       break;
     67:     case NEP_LARGEST_REAL:
     68:       *sigma = PETSC_MAX_REAL;
     69:       break;
     70:     case NEP_SMALLEST_REAL:
     71:       *sigma = PETSC_MIN_REAL;
     72:       break;
     73:     case NEP_TARGET_MAGNITUDE:
     74:     case NEP_TARGET_REAL:
     75:     case NEP_TARGET_IMAGINARY:
     76:       *sigma = nep->target;
     77:       break;
     78:   }
     79:   return 0;
     80: }

     82: /*
     83:   NEPConvergedRelative - Checks convergence relative to the eigenvalue.
     84: */
     85: PetscErrorCode NEPConvergedRelative(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
     86: {
     87:   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: {
     99:   *errest = res;
    100:   return 0;
    101: }

    103: /*
    104:   NEPConvergedNorm - Checks convergence relative to the matrix norms.
    105: */
    106: PetscErrorCode NEPConvergedNorm(NEP nep,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
    107: {
    108:   PetscScalar    s;
    109:   PetscReal      w=0.0;
    110:   PetscInt       j;
    111:   PetscBool      flg;

    113:   if (nep->fui!=NEP_USER_INTERFACE_SPLIT) {
    114:     NEPComputeFunction(nep,eigr,nep->function,nep->function);
    115:     MatHasOperation(nep->function,MATOP_NORM,&flg);
    117:     MatNorm(nep->function,NORM_INFINITY,&w);
    118:   } else {
    119:     /* initialization of matrix norms */
    120:     if (!nep->nrma[0]) {
    121:       for (j=0;j<nep->nt;j++) {
    122:         MatHasOperation(nep->A[j],MATOP_NORM,&flg);
    124:         MatNorm(nep->A[j],NORM_INFINITY,&nep->nrma[j]);
    125:       }
    126:     }
    127:     for (j=0;j<nep->nt;j++) {
    128:       FNEvaluateFunction(nep->f[j],eigr,&s);
    129:       w = w + nep->nrma[j]*PetscAbsScalar(s);
    130:     }
    131:   }
    132:   *errest = res/w;
    133:   return 0;
    134: }

    136: /*@C
    137:    NEPStoppingBasic - Default routine to determine whether the outer eigensolver
    138:    iteration must be stopped.

    140:    Collective on nep

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

    150:    Output Parameter:
    151: .  reason - result of the stopping test

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

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

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

    164:    Level: advanced

    166: .seealso: NEPSetStoppingTest(), NEPConvergedReason, NEPGetConvergedReason()
    167: @*/
    168: PetscErrorCode NEPStoppingBasic(NEP nep,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nev,NEPConvergedReason *reason,void *ctx)
    169: {
    170:   *reason = NEP_CONVERGED_ITERATING;
    171:   if (nconv >= nev) {
    172:     PetscInfo(nep,"Nonlinear eigensolver finished successfully: %" PetscInt_FMT " eigenpairs converged at iteration %" PetscInt_FMT "\n",nconv,its);
    173:     *reason = NEP_CONVERGED_TOL;
    174:   } else if (its >= max_it) {
    175:     *reason = NEP_DIVERGED_ITS;
    176:     PetscInfo(nep,"Nonlinear eigensolver iteration reached maximum number of iterations (%" PetscInt_FMT ")\n",its);
    177:   }
    178:   return 0;
    179: }

    181: PetscErrorCode NEPComputeVectors_Schur(NEP nep)
    182: {
    183:   Mat            Z;

    185:   DSVectors(nep->ds,DS_MAT_X,NULL,NULL);
    186:   DSGetMat(nep->ds,DS_MAT_X,&Z);
    187:   BVMultInPlace(nep->V,Z,0,nep->nconv);
    188:   DSRestoreMat(nep->ds,DS_MAT_X,&Z);
    189:   BVNormalize(nep->V,nep->eigi);
    190:   return 0;
    191: }