Date: 2022-03-31T15:28:53+00:00

Actual source code: test7.c
slepc-3.17.0 2022-03-31
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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.\n\n";

     13: #include <slepcds.h>

     15: int main(int argc,char **argv)
     16: {
     17:   DS             ds;
     18:   SlepcSC        sc;
     19:   PetscReal      sigma,rnorm,aux;
     20:   PetscScalar    *A,*U,*w,d;
     21:   PetscInt       i,j,k,n=15,m=10,m1,ld;
     22:   PetscViewer    viewer;
     23:   PetscBool      verbose,extrarow;

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

     33:   /* Create DS object */
     34:   DSCreate(PETSC_COMM_WORLD,&ds);
     35:   DSSetType(ds,DSSVD);
     36:   DSSetFromOptions(ds);
     37:   ld = n+2;  /* test leading dimension larger than n */
     38:   DSAllocate(ds,ld);
     39:   DSSetDimensions(ds,n,0,0);
     40:   DSSVDSetDimensions(ds,m);
     41:   DSSVDGetDimensions(ds,&m1);
     43:   DSSetExtraRow(ds,extrarow);

     45:   /* Set up viewer */
     46:   PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);
     47:   PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);
     48:   DSView(ds,viewer);
     49:   PetscViewerPopFormat(viewer);

     51:   /* Fill with a rectangular Toeplitz matrix */
     52:   DSGetArray(ds,DS_MAT_A,&A);
     53:   for (i=0;i<k;i++) A[i+i*ld]=1.0;
     54:   for (j=1;j<3;j++) {
     55:     for (i=0;i<n-j;i++) { if ((i+j)<m) A[i+(i+j)*ld]=(PetscScalar)(j+1); }
     56:   }
     57:   for (j=1;j<n/2;j++) {
     58:     for (i=0;i<n-j;i++) { if ((i+j)<n && i<m) A[(i+j)+i*ld]=-1.0; }
     59:   }
     60:   if (extrarow) { A[n-2+m*ld]=1.0; A[n-1+m*ld]=1.0; }  /* really an extra column */
     61:   DSRestoreArray(ds,DS_MAT_A,&A);
     62:   DSSetState(ds,DS_STATE_RAW);
     63:   if (verbose) {
     64:     PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);
     65:     PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");
     66:   }
     67:   DSView(ds,viewer);

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

     84:   /* Print singular values */
     85:   PetscPrintf(PETSC_COMM_WORLD,"Computed singular values =\n");
     86:   for (i=0;i<k;i++) {
     87:     sigma = PetscRealPart(w[i]);
     88:     PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)sigma);
     89:   }

     91:   if (extrarow) {
     92:     /* Check that extra column is correct */
     93:     DSGetArray(ds,DS_MAT_A,&A);
     94:     DSGetArray(ds,DS_MAT_U,&U);
     95:     d = 0.0;
     96:     for (i=0;i<n;i++) d += A[i+m*ld]-U[n-2+i*ld]-U[n-1+i*ld];
     97:     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));
     98:     DSRestoreArray(ds,DS_MAT_A,&A);
     99:     DSRestoreArray(ds,DS_MAT_U,&U);
    100:   }

    102:   /* Singular vectors */
    103:   DSVectors(ds,DS_MAT_U,NULL,NULL);  /* all singular vectors */
    104:   j = 0;
    105:   rnorm = 0.0;
    106:   DSGetArray(ds,DS_MAT_U,&U);
    107:   for (i=0;i<n;i++) {
    108:     aux = PetscAbsScalar(U[i+j*ld]);
    109:     rnorm += aux*aux;
    110:   }
    111:   DSRestoreArray(ds,DS_MAT_U,&U);
    112:   rnorm = PetscSqrtReal(rnorm);
    113:   PetscPrintf(PETSC_COMM_WORLD,"Norm of 1st U vector = %.3f\n",(double)rnorm);

    115:   PetscFree(w);
    116:   DSDestroy(&ds);
    117:   SlepcFinalize();
    118:   return 0;
    119: }

    121: /*TEST

    123:    test:
    124:       suffix: 1
    125:       requires: !single

    127:    test:
    128:       suffix: 2
    129:       args: -extrarow
    130:       requires: !single

    132: TEST*/