Actual source code: test7.c

slepc-3.11.2 2019-07-30
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  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2019, 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: {
 18:   DS             ds;
 19:   SlepcSC        sc;
 20:   PetscReal      sigma,rnorm,aux;
 21:   PetscScalar    *A,*U,*w;
 22:   PetscInt       i,j,k,n=15,m=10,ld;
 23:   PetscViewer    viewer;
 24:   PetscBool      verbose;

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

 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,m,0,0);

 41:   /* Set up viewer */
 42:   PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);
 43:   PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);
 44:   DSView(ds,viewer);
 45:   PetscViewerPopFormat(viewer);

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

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

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

 85:   /* Singular vectors */
 86:   DSVectors(ds,DS_MAT_U,NULL,NULL);  /* all singular vectors */
 87:   j = 0;
 88:   rnorm = 0.0;
 89:   DSGetArray(ds,DS_MAT_U,&U);
 90:   for (i=0;i<n;i++) {
 91:     aux = PetscAbsScalar(U[i+j*ld]);
 92:     rnorm += aux*aux;
 93:   }
 94:   DSRestoreArray(ds,DS_MAT_U,&U);
 95:   rnorm = PetscSqrtReal(rnorm);
 96:   PetscPrintf(PETSC_COMM_WORLD,"Norm of 1st U vector = %.3f\n",(double)rnorm);

 98:   PetscFree(w);
 99:   DSDestroy(&ds);
100:   SlepcFinalize();
101:   return ierr;
102: }

104: /*TEST

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

110: TEST*/