Date: 2023-01-26T12:18:07+00:00

Actual source code: test8.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: */

     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;

     26:   SlepcInitialize(&argc,&argv,(char*)0,help);
     27:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     28:   m = n;
     29:   PetscPrintf(PETSC_COMM_WORLD,"Solve a Dense System of type SVD with compact storage - dimension %" PetscInt_FMT "x%" PetscInt_FMT ".\n",n,m);
     30:   PetscOptionsGetInt(NULL,NULL,"-l",&l,NULL);
     31:   PetscOptionsGetInt(NULL,NULL,"-k",&k,NULL);
     33:   PetscOptionsHasName(NULL,NULL,"-verbose",&verbose);
     34:   PetscOptionsHasName(NULL,NULL,"-extrarow",&extrarow);

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

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

     54:   /* Fill upper arrow-bidiagonal matrix */
     55:   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:   DSRestoreArrayReal(ds,DS_MAT_T,&T);
     60:   if (l==0 && k==0) DSSetState(ds,DS_STATE_INTERMEDIATE);
     61:   else DSSetState(ds,DS_STATE_RAW);
     62:   PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");
     63:   DSView(ds,viewer);

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

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

     87:   if (extrarow) {
     88:     /* Check that extra row is correct */
     89:     DSGetArrayReal(ds,DS_MAT_T,&T);
     90:     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) PetscPrintf(PETSC_COMM_WORLD,"Warning: there is a mismatch in the extra row of %g\n",(double)PetscAbsScalar(d));
     94:     DSRestoreArrayReal(ds,DS_MAT_T,&T);
     95:     DSRestoreArray(ds,DS_MAT_U,&U);
     96:   }
     97:   PetscFree(w);
     98:   DSDestroy(&ds);
     99:   SlepcFinalize();
    100:   return 0;
    101: }

    103: /*TEST

    105:    test:
    106:       suffix: 1
    107:       requires: !single

    109:    test:
    110:       args: -l 0 -k 0
    111:       suffix: 2
    112:       requires: !single

    114:    test:
    115:       args: -extrarow
    116:       suffix: 3
    117:       requires: !single

    119: TEST*/