Date: 2026-03-09T09:12:11+00:00

Actual source code: test26.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 DSHSVD 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,*D,sigma;
     20:   PetscScalar    *U,*w,d;
     21:   PetscInt       i,n=10,m,l=2,k=5,p=1,ld;
     22:   PetscViewer    viewer;
     23:   PetscBool      verbose,extrarow,reorthog,flg;

     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 HSVD 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:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-p",&p,NULL));
     33:   PetscCheck(l<=n && k<=n && l<=k && p>=0 && p<=n-l,PETSC_COMM_WORLD,PETSC_ERR_USER_INPUT,"Wrong value of dimensions");
     34:   PetscCall(PetscOptionsHasName(NULL,NULL,"-verbose",&verbose));
     35:   PetscCall(PetscOptionsHasName(NULL,NULL,"-extrarow",&extrarow));
     36:   PetscCall(PetscOptionsHasName(NULL,NULL,"-reorthog",&reorthog));

     38:   /* Create DS object */
     39:   PetscCall(DSCreate(PETSC_COMM_WORLD,&ds));
     40:   PetscCall(DSSetType(ds,DSHSVD));
     41:   PetscCall(DSSetFromOptions(ds));
     42:   ld = n+2;  /* test leading dimension larger than n */
     43:   PetscCall(DSAllocate(ds,ld));
     44:   PetscCall(DSSetDimensions(ds,n,l,k));
     45:   PetscCall(DSHSVDSetDimensions(ds,m));
     46:   PetscCall(DSSetCompact(ds,PETSC_TRUE));
     47:   PetscCall(DSSetExtraRow(ds,extrarow));
     48:   PetscCall(DSHSVDSetReorthogonalize(ds,reorthog));
     49:   PetscCall(DSHSVDGetReorthogonalize(ds,&flg));
     50:   if (flg) PetscCall(PetscPrintf(PETSC_COMM_WORLD,"reorthogonalizing\n"));

     52:   /* Set up viewer */
     53:   PetscCall(PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer));
     54:   PetscCall(PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL));
     55:   PetscCall(DSView(ds,viewer));
     56:   PetscCall(PetscViewerPopFormat(viewer));
     57:   PetscCall(PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB));

     59:   /* Fill upper arrow-bidiagonal matrix and signature matrix */
     60:   PetscCall(DSGetArrayReal(ds,DS_MAT_T,&T));
     61:   for (i=0;i<n;i++) T[i] = (PetscReal)(i+1);
     62:   for (i=l;i<n-1;i++) T[i+ld] = 1.0;
     63:   if (extrarow) T[n-1+ld] = 1.0;
     64:   PetscCall(DSRestoreArrayReal(ds,DS_MAT_T,&T));
     65:   PetscCall(DSGetArrayReal(ds,DS_MAT_D,&D));
     66:   for (i=0;i<n;i++) D[i] = (i>=l && i<l+p)? -1.0: 1.0;
     67:   PetscCall(DSRestoreArrayReal(ds,DS_MAT_D,&D));
     68:   if (l==0 && k==0) PetscCall(DSSetState(ds,DS_STATE_INTERMEDIATE));
     69:   else PetscCall(DSSetState(ds,DS_STATE_RAW));
     70:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n"));
     71:   PetscCall(DSView(ds,viewer));

     73:   /* Solve */
     74:   PetscCall(PetscMalloc1(n,&w));
     75:   PetscCall(DSGetSlepcSC(ds,&sc));
     76:   sc->comparison    = SlepcCompareLargestReal;
     77:   sc->comparisonctx = NULL;
     78:   sc->map           = NULL;
     79:   sc->mapobj        = NULL;
     80:   PetscCall(DSSolve(ds,w,NULL));
     81:   PetscCall(DSSort(ds,w,NULL,NULL,NULL,NULL));
     82:   if (extrarow) PetscCall(DSUpdateExtraRow(ds));
     83:   if (verbose) {
     84:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n"));
     85:     PetscCall(DSView(ds,viewer));
     86:   }

     88:   /* Print singular values */
     89:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Computed singular values =\n"));
     90:   for (i=0;i<n;i++) {
     91:     sigma = PetscRealPart(w[i]);
     92:     PetscCall(PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)sigma));
     93:   }

     95:   if (extrarow) {
     96:     /* Check that extra row is correct */
     97:     PetscCall(DSGetArrayReal(ds,DS_MAT_T,&T));
     98:     PetscCall(DSGetArray(ds,DS_MAT_U,&U));
     99:     PetscCall(DSGetArrayReal(ds,DS_MAT_D,&D));
    100:     d = 0.0;
    101:     for (i=l;i<n;i++) d += T[i+ld]-D[i]*U[n-1+i*ld];
    102:     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)));
    103:     PetscCall(DSRestoreArrayReal(ds,DS_MAT_T,&T));
    104:     PetscCall(DSRestoreArray(ds,DS_MAT_U,&U));
    105:     PetscCall(DSRestoreArrayReal(ds,DS_MAT_D,&D));
    106:   }
    107:   PetscCall(PetscFree(w));
    108:   PetscCall(DSDestroy(&ds));
    109:   PetscCall(SlepcFinalize());
    110:   return 0;
    111: }

    113: /*TEST

    115:    test:
    116:       suffix: 1
    117:       requires: !single

    119:    test:
    120:       args: -l 0 -k 0
    121:       suffix: 2
    122:       requires: !single

    124:    test:
    125:       args: -extrarow -reorthog {{0 1}}
    126:       suffix: 3
    127:       requires: !single
    128:       filter: grep -v reorthogonalizing

    130: TEST*/