Actual source code: test7.c

slepc-3.7.1 2016-05-27
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  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2016, 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,NULL,"-n",&n,NULL);
 41:   PetscOptionsGetInt(NULL,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,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 ierr;
103: }