Date: 2022-11-02T11:47:07+00:00

Actual source code: svddefault.c
slepc-3.18.1 2022-11-02
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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 SVD operations
     12: */

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

     16: /*
     17:   SVDConvergedAbsolute - Checks convergence absolutely.
     18: */
     19: PetscErrorCode SVDConvergedAbsolute(SVD svd,PetscReal sigma,PetscReal res,PetscReal *errest,void *ctx)
     20: {
     21:   *errest = res;
     22:   return 0;
     23: }

     25: /*
     26:   SVDConvergedRelative - Checks convergence relative to the singular value.
     27: */
     28: PetscErrorCode SVDConvergedRelative(SVD svd,PetscReal sigma,PetscReal res,PetscReal *errest,void *ctx)
     29: {
     30:   *errest = res/sigma;
     31:   return 0;
     32: }

     34: /*
     35:   SVDConvergedNorm - Checks convergence relative to the matrix norms.
     36: */
     37: PetscErrorCode SVDConvergedNorm(SVD svd,PetscReal sigma,PetscReal res,PetscReal *errest,void *ctx)
     38: {
     39:   *errest = res/PetscMax(svd->nrma,svd->nrmb);
     40:   return 0;
     41: }

     43: /*
     44:   SVDConvergedMaxIt - Always returns Inf to force reaching the maximum number of iterations.
     45: */
     46: PetscErrorCode SVDConvergedMaxIt(SVD svd,PetscReal sigma,PetscReal res,PetscReal *errest,void *ctx)
     47: {
     48:   *errest = PETSC_MAX_REAL;
     49:   return 0;
     50: }

     52: /*@C
     53:    SVDStoppingBasic - Default routine to determine whether the outer singular value
     54:    solver iteration must be stopped.

     56:    Collective on svd

     58:    Input Parameters:
     59: +  svd    - singular value solver context obtained from SVDCreate()
     60: .  its    - current number of iterations
     61: .  max_it - maximum number of iterations
     62: .  nconv  - number of currently converged singular triplets
     63: .  nsv    - number of requested singular triplets
     64: -  ctx    - context (not used here)

     66:    Output Parameter:
     67: .  reason - result of the stopping test

     69:    Notes:
     70:    A positive value of reason indicates that the iteration has finished successfully
     71:    (converged), and a negative value indicates an error condition (diverged). If
     72:    the iteration needs to be continued, reason must be set to SVD_CONVERGED_ITERATING
     73:    (zero).

     75:    SVDStoppingBasic() will stop if all requested singular values are converged, or if
     76:    the maximum number of iterations has been reached.

     78:    Use SVDSetStoppingTest() to provide your own test instead of using this one.

     80:    Level: advanced

     82: .seealso: SVDSetStoppingTest(), SVDConvergedReason, SVDGetConvergedReason()
     83: @*/
     84: PetscErrorCode SVDStoppingBasic(SVD svd,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nsv,SVDConvergedReason *reason,void *ctx)
     85: {
     86:   *reason = SVD_CONVERGED_ITERATING;
     87:   if (nconv >= nsv) {
     88:     PetscInfo(svd,"Singular value solver finished successfully: %" PetscInt_FMT " singular triplets converged at iteration %" PetscInt_FMT "\n",nconv,its);
     89:     *reason = SVD_CONVERGED_TOL;
     90:   } else if (its >= max_it) {
     91:     if (svd->conv == SVD_CONV_MAXIT) *reason = SVD_CONVERGED_MAXIT;
     92:     else {
     93:       *reason = SVD_DIVERGED_ITS;
     94:       PetscInfo(svd,"Singular value solver iteration reached maximum number of iterations (%" PetscInt_FMT ")\n",its);
     95:     }
     96:   }
     97:   return 0;
     98: }

    100: /*@
    101:    SVDSetWorkVecs - Sets a number of work vectors into an SVD object.

    103:    Collective on svd

    105:    Input Parameters:
    106: +  svd    - singular value solver context
    107: .  nleft  - number of work vectors of dimension equal to left singular vector
    108: -  nright - number of work vectors of dimension equal to right singular vector

    110:    Developer Notes:
    111:    This is SLEPC_EXTERN because it may be required by user plugin SVD
    112:    implementations.

    114:    Level: developer

    116: .seealso: SVDSetUp()
    117: @*/
    118: PetscErrorCode SVDSetWorkVecs(SVD svd,PetscInt nleft,PetscInt nright)
    119: {
    120:   Vec            t;

    128:   if (svd->nworkl < nleft) {
    129:     VecDestroyVecs(svd->nworkl,&svd->workl);
    130:     svd->nworkl = nleft;
    131:     if (svd->isgeneralized) SVDCreateLeftTemplate(svd,&t);
    132:     else MatCreateVecsEmpty(svd->OP,NULL,&t);
    133:     VecDuplicateVecs(t,nleft,&svd->workl);
    134:     VecDestroy(&t);
    135:   }
    136:   if (svd->nworkr < nright) {
    137:     VecDestroyVecs(svd->nworkr,&svd->workr);
    138:     svd->nworkr = nright;
    139:     MatCreateVecsEmpty(svd->OP,&t,NULL);
    140:     VecDuplicateVecs(t,nright,&svd->workr);
    141:     VecDestroy(&t);
    142:   }
    143:   return 0;
    144: }