Date: 2024-10-28T09:14:14+00:00

Actual source code: svddefault.c
slepc-3.22.1 2024-10-28
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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:   PetscFunctionBegin;
     22:   *errest = res;
     23:   PetscFunctionReturn(PETSC_SUCCESS);
     24: }

     26: /*
     27:   SVDConvergedRelative - Checks convergence relative to the singular value.
     28: */
     29: PetscErrorCode SVDConvergedRelative(SVD svd,PetscReal sigma,PetscReal res,PetscReal *errest,void *ctx)
     30: {
     31:   PetscFunctionBegin;
     32:   *errest = (sigma!=0.0)? res/sigma: PETSC_MAX_REAL;
     33:   PetscFunctionReturn(PETSC_SUCCESS);
     34: }

     36: /*
     37:   SVDConvergedNorm - Checks convergence relative to the matrix norms.
     38: */
     39: PetscErrorCode SVDConvergedNorm(SVD svd,PetscReal sigma,PetscReal res,PetscReal *errest,void *ctx)
     40: {
     41:   PetscFunctionBegin;
     42:   *errest = res/PetscMax(svd->nrma,svd->nrmb);
     43:   PetscFunctionReturn(PETSC_SUCCESS);
     44: }

     46: /*
     47:   SVDConvergedMaxIt - Always returns Inf to force reaching the maximum number of iterations.
     48: */
     49: PetscErrorCode SVDConvergedMaxIt(SVD svd,PetscReal sigma,PetscReal res,PetscReal *errest,void *ctx)
     50: {
     51:   PetscFunctionBegin;
     52:   *errest = PETSC_MAX_REAL;
     53:   PetscFunctionReturn(PETSC_SUCCESS);
     54: }

     56: /*@C
     57:    SVDStoppingBasic - Default routine to determine whether the outer singular value
     58:    solver iteration must be stopped.

     60:    Collective

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

     70:    Output Parameter:
     71: .  reason - result of the stopping test

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

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

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

     84:    Level: advanced

     86: .seealso: SVDSetStoppingTest(), SVDConvergedReason, SVDGetConvergedReason()
     87: @*/
     88: PetscErrorCode SVDStoppingBasic(SVD svd,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nsv,SVDConvergedReason *reason,void *ctx)
     89: {
     90:   PetscFunctionBegin;
     91:   *reason = SVD_CONVERGED_ITERATING;
     92:   if (nconv >= nsv) {
     93:     PetscCall(PetscInfo(svd,"Singular value solver finished successfully: %" PetscInt_FMT " singular triplets converged at iteration %" PetscInt_FMT "\n",nconv,its));
     94:     *reason = SVD_CONVERGED_TOL;
     95:   } else if (its >= max_it) {
     96:     if (svd->conv == SVD_CONV_MAXIT) *reason = SVD_CONVERGED_MAXIT;
     97:     else {
     98:       *reason = SVD_DIVERGED_ITS;
     99:       PetscCall(PetscInfo(svd,"Singular value solver iteration reached maximum number of iterations (%" PetscInt_FMT ")\n",its));
    100:     }
    101:   }
    102:   PetscFunctionReturn(PETSC_SUCCESS);
    103: }

    105: /*@
    106:    SVDSetWorkVecs - Sets a number of work vectors into an SVD object.

    108:    Collective

    110:    Input Parameters:
    111: +  svd    - singular value solver context
    112: .  nleft  - number of work vectors of dimension equal to left singular vector
    113: -  nright - number of work vectors of dimension equal to right singular vector

    115:    Developer Notes:
    116:    This is SLEPC_EXTERN because it may be required by user plugin SVD
    117:    implementations.

    119:    Level: developer

    121: .seealso: SVDSetUp()
    122: @*/
    123: PetscErrorCode SVDSetWorkVecs(SVD svd,PetscInt nleft,PetscInt nright)
    124: {
    125:   Vec            t;

    127:   PetscFunctionBegin;
    131:   PetscCheck(nleft>=0,PetscObjectComm((PetscObject)svd),PETSC_ERR_ARG_OUTOFRANGE,"nleft must be >= 0: nleft = %" PetscInt_FMT,nleft);
    132:   PetscCheck(nright>=0,PetscObjectComm((PetscObject)svd),PETSC_ERR_ARG_OUTOFRANGE,"nright must be >= 0: nright = %" PetscInt_FMT,nright);
    133:   PetscCheck(nleft>0 || nright>0,PetscObjectComm((PetscObject)svd),PETSC_ERR_ARG_OUTOFRANGE,"nleft and nright cannot be both zero");
    134:   if (svd->nworkl < nleft) {
    135:     PetscCall(VecDestroyVecs(svd->nworkl,&svd->workl));
    136:     svd->nworkl = nleft;
    137:     if (svd->isgeneralized) PetscCall(SVDCreateLeftTemplate(svd,&t));
    138:     else PetscCall(MatCreateVecsEmpty(svd->OP,NULL,&t));
    139:     PetscCall(VecDuplicateVecs(t,nleft,&svd->workl));
    140:     PetscCall(VecDestroy(&t));
    141:   }
    142:   if (svd->nworkr < nright) {
    143:     PetscCall(VecDestroyVecs(svd->nworkr,&svd->workr));
    144:     svd->nworkr = nright;
    145:     PetscCall(MatCreateVecsEmpty(svd->OP,&t,NULL));
    146:     PetscCall(VecDuplicateVecs(t,nright,&svd->workr));
    147:     PetscCall(VecDestroy(&t));
    148:   }
    149:   PetscFunctionReturn(PETSC_SUCCESS);
    150: }