Date: 2026-01-20T11:35:26+00:00

Actual source code: test8.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: */

     11: static char help[] = "Test DSSVD with compact storage.\n\n";

     13: #include <slepcds.h>

     15: int main(int argc,char **argv)
     16: {
     17:   DS             ds;
     18:   SlepcSC        sc;
     19:   PetscReal      *T,sigma;
     20:   PetscScalar    *U,*w,d;
     21:   PetscInt       i,n=10,m,l=2,k=5,ld;
     22:   PetscViewer    viewer;
     23:   PetscBool      verbose,extrarow;

     25:   PetscFunctionBeginUser;
     26:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
     27:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     28:   m = n;
     29:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Solve a Dense System of type SVD with compact storage - dimension %" PetscInt_FMT "x%" PetscInt_FMT ".\n",n,m));
     30:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-l",&l,NULL));
     31:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-k",&k,NULL));
     32:   PetscCheck(l<=n && k<=n && l<=k,PETSC_COMM_WORLD,PETSC_ERR_USER_INPUT,"Wrong value of dimensions");
     33:   PetscCall(PetscOptionsHasName(NULL,NULL,"-verbose",&verbose));
     34:   PetscCall(PetscOptionsHasName(NULL,NULL,"-extrarow",&extrarow));

     36:   /* Create DS object */
     37:   PetscCall(DSCreate(PETSC_COMM_WORLD,&ds));
     38:   PetscCall(DSSetType(ds,DSSVD));
     39:   PetscCall(DSSetFromOptions(ds));
     40:   ld = n+2;  /* test leading dimension larger than n */
     41:   PetscCall(DSAllocate(ds,ld));
     42:   PetscCall(DSSetDimensions(ds,n,l,k));
     43:   PetscCall(DSSVDSetDimensions(ds,m));
     44:   PetscCall(DSSetCompact(ds,PETSC_TRUE));
     45:   PetscCall(DSSetExtraRow(ds,extrarow));

     47:   /* Set up viewer */
     48:   PetscCall(PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer));
     49:   PetscCall(PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL));
     50:   PetscCall(DSView(ds,viewer));
     51:   PetscCall(PetscViewerPopFormat(viewer));
     52:   PetscCall(PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB));

     54:   /* Fill upper arrow-bidiagonal matrix */
     55:   PetscCall(DSGetArrayReal(ds,DS_MAT_T,&T));
     56:   for (i=0;i<n;i++) T[i] = (PetscReal)(i+1);
     57:   for (i=l;i<n-1;i++) T[i+ld] = 1.0;
     58:   if (extrarow) T[n-1+ld] = 1.0;
     59:   PetscCall(DSRestoreArrayReal(ds,DS_MAT_T,&T));
     60:   if (l==0 && k==0) PetscCall(DSSetState(ds,DS_STATE_INTERMEDIATE));
     61:   else PetscCall(DSSetState(ds,DS_STATE_RAW));
     62:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n"));
     63:   PetscCall(DSView(ds,viewer));

     65:   /* Solve */
     66:   PetscCall(PetscMalloc1(n,&w));
     67:   PetscCall(DSGetSlepcSC(ds,&sc));
     68:   sc->comparison    = SlepcCompareLargestReal;
     69:   sc->comparisonctx = NULL;
     70:   sc->map           = NULL;
     71:   sc->mapobj        = NULL;
     72:   PetscCall(DSSolve(ds,w,NULL));
     73:   PetscCall(DSSort(ds,w,NULL,NULL,NULL,NULL));
     74:   if (extrarow) PetscCall(DSUpdateExtraRow(ds));
     75:   if (verbose) {
     76:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n"));
     77:     PetscCall(DSView(ds,viewer));
     78:   }

     80:   /* Print singular values */
     81:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Computed singular values =\n"));
     82:   for (i=0;i<n;i++) {
     83:     sigma = PetscRealPart(w[i]);
     84:     PetscCall(PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)sigma));
     85:   }

     87:   if (extrarow) {
     88:     /* Check that extra row is correct */
     89:     PetscCall(DSGetArrayReal(ds,DS_MAT_T,&T));
     90:     PetscCall(DSGetArray(ds,DS_MAT_U,&U));
     91:     d = 0.0;
     92:     for (i=l;i<n;i++) d += T[i+ld]-U[n-1+i*ld];
     93:     if (PetscAbsScalar(d)>10*PETSC_MACHINE_EPSILON) PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Warning: there is a mismatch in the extra row of %g\n",(double)PetscAbsScalar(d)));
     94:     PetscCall(DSRestoreArrayReal(ds,DS_MAT_T,&T));
     95:     PetscCall(DSRestoreArray(ds,DS_MAT_U,&U));
     96:   }
     97:   PetscCall(PetscFree(w));
     98:   PetscCall(DSDestroy(&ds));
     99:   PetscCall(SlepcFinalize());
    100:   return 0;
    101: }

    103: /*TEST

    105:    test:
    106:       args: -ds_method {{0 1}}
    107:       suffix: 1
    108:       filter: grep -v "solving the problem"
    109:       requires: !single

    111:    test:
    112:       args: -l 0 -k 0 -ds_method {{0 1}}
    113:       suffix: 2
    114:       filter: grep -v "solving the problem"
    115:       requires: !single

    117:    test:
    118:       args: -extrarow -ds_method {{0 1}}
    119:       suffix: 3
    120:       filter: grep -v "solving the problem"
    121:       requires: !single

    123: TEST*/