Date: 2015-09-03T15:03:45+00:00

Actual source code: test7.c
slepc-3.6.1 2015-09-03
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2015, Universitat Politecnica de Valencia, Spain

      6:    This file is part of SLEPc.

      8:    SLEPc is free software: you can redistribute it and/or modify it under  the
      9:    terms of version 3 of the GNU Lesser General Public License as published by
     10:    the Free Software Foundation.

     12:    SLEPc  is  distributed in the hope that it will be useful, but WITHOUT  ANY
     13:    WARRANTY;  without even the implied warranty of MERCHANTABILITY or  FITNESS
     14:    FOR  A  PARTICULAR PURPOSE. See the GNU Lesser General Public  License  for
     15:    more details.

     17:    You  should have received a copy of the GNU Lesser General  Public  License
     18:    along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
     19:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     20: */

     22: static char help[] = "Test DSSVD.\n\n";

     24: #include <slepcds.h>

     28: int main(int argc,char **argv)
     29: {
     31:   DS             ds;
     32:   SlepcSC        sc;
     33:   PetscReal      sigma;
     34:   PetscScalar    *A,*w;
     35:   PetscInt       i,j,k,n=15,m=10,ld;
     36:   PetscViewer    viewer;
     37:   PetscBool      verbose;

     39:   SlepcInitialize(&argc,&argv,(char*)0,help);
     40:   PetscOptionsGetInt(NULL,"-n",&n,NULL);
     41:   PetscOptionsGetInt(NULL,"-m",&m,NULL);
     42:   k = PetscMin(n,m);
     43:   PetscPrintf(PETSC_COMM_WORLD,"Solve a Dense System of type SVD - dimension %Dx%D.\n",n,m);
     44:   PetscOptionsHasName(NULL,"-verbose",&verbose);

     46:   /* Create DS object */
     47:   DSCreate(PETSC_COMM_WORLD,&ds);
     48:   DSSetType(ds,DSSVD);
     49:   DSSetFromOptions(ds);
     50:   ld = n+2;  /* test leading dimension larger than n */
     51:   DSAllocate(ds,ld);
     52:   DSSetDimensions(ds,n,m,0,0);

     54:   /* Set up viewer */
     55:   PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);
     56:   PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);
     57:   DSView(ds,viewer);
     58:   PetscViewerPopFormat(viewer);
     59:   if (verbose) {
     60:     PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);
     61:   }

     63:   /* Fill with a rectangular Toeplitz matrix */
     64:   DSGetArray(ds,DS_MAT_A,&A);
     65:   for (i=0;i<k;i++) A[i+i*ld]=1.0;
     66:   for (j=1;j<3;j++) {
     67:     for (i=0;i<n-j;i++) { if ((i+j)<m) A[i+(i+j)*ld]=(PetscScalar)(j+1); }
     68:   }
     69:   for (j=1;j<n/2;j++) {
     70:     for (i=0;i<n-j;i++) { if ((i+j)<n && i<m) A[(i+j)+i*ld]=-1.0; }
     71:   }
     72:   DSRestoreArray(ds,DS_MAT_A,&A);
     73:   DSSetState(ds,DS_STATE_RAW);
     74:   if (verbose) {
     75:     PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");
     76:     DSView(ds,viewer);
     77:   }

     79:   /* Solve */
     80:   PetscMalloc1(k,&w);
     81:   DSGetSlepcSC(ds,&sc);
     82:   sc->comparison    = SlepcCompareLargestReal;
     83:   sc->comparisonctx = NULL;
     84:   sc->map           = NULL;
     85:   sc->mapobj        = NULL;
     86:   DSSolve(ds,w,NULL);
     87:   DSSort(ds,w,NULL,NULL,NULL,NULL);
     88:   if (verbose) {
     89:     PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n");
     90:     DSView(ds,viewer);
     91:   }

     93:   /* Print singular values */
     94:   PetscPrintf(PETSC_COMM_WORLD,"Computed singular values =\n");
     95:   for (i=0;i<k;i++) {
     96:     sigma = PetscRealPart(w[i]);
     97:     PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)sigma);
     98:   }
     99:   PetscFree(w);
    100:   DSDestroy(&ds);
    101:   SlepcFinalize();
    102:   return 0;
    103: }