Date: 2021-02-01T14:41:44+00:00

Actual source code: test2.c
slepc-3.14.2 2021-02-01
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2020, 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 DSHEP.\n\n";

     13: #include <slepcds.h>

     15: int main(int argc,char **argv)
     16: {
     18:   DS             ds;
     19:   SlepcSC        sc;
     20:   PetscScalar    *A,*X,*eig;
     21:   PetscReal      rnorm,aux;
     22:   PetscInt       i,j,n=10,ld;
     23:   PetscViewer    viewer;
     24:   PetscBool      verbose,extrarow;

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

     32:   /* Create DS object */
     33:   DSCreate(PETSC_COMM_WORLD,&ds);
     34:   DSSetType(ds,DSHEP);
     35:   DSSetFromOptions(ds);
     36:   ld = n+2;  /* test leading dimension larger than n */
     37:   DSAllocate(ds,ld);
     38:   DSSetDimensions(ds,n,0,0,0);
     39:   DSSetExtraRow(ds,extrarow);

     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);
     46:   if (verbose) {
     47:     PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);
     48:   }

     50:   /* Fill with a symmetric Toeplitz matrix */
     51:   DSGetArray(ds,DS_MAT_A,&A);
     52:   for (i=0;i<n;i++) A[i+i*ld]=2.0;
     53:   for (j=1;j<3;j++) {
     54:     for (i=0;i<n-j;i++) { A[i+(i+j)*ld]=1.0; A[(i+j)+i*ld]=1.0; }
     55:   }
     56:   if (extrarow) { A[n+(n-2)*ld]=1.0; A[n+(n-1)*ld]=1.0; }
     57:   DSRestoreArray(ds,DS_MAT_A,&A);
     58:   DSSetState(ds,DS_STATE_RAW);
     59:   if (verbose) {
     60:     PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");
     61:     DSView(ds,viewer);
     62:   }

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

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

     85:   /* Eigenvectors */
     86:   j = 2;
     87:   DSVectors(ds,DS_MAT_X,&j,&rnorm);  /* third eigenvector */
     88:   PetscPrintf(PETSC_COMM_WORLD,"Value of rnorm for 3rd vector = %.3f\n",(double)rnorm);
     89:   DSVectors(ds,DS_MAT_X,NULL,NULL);  /* all eigenvectors */
     90:   j = 0;
     91:   rnorm = 0.0;
     92:   DSGetArray(ds,DS_MAT_X,&X);
     93:   for (i=0;i<n;i++) {
     94:     aux = PetscAbsScalar(X[i+j*ld]);
     95:     rnorm += aux*aux;
     96:   }
     97:   DSRestoreArray(ds,DS_MAT_X,&X);
     98:   rnorm = PetscSqrtReal(rnorm);
     99:   PetscPrintf(PETSC_COMM_WORLD,"Norm of 1st vector = %.3f\n",(double)rnorm);
    100:   if (verbose) {
    101:     PetscPrintf(PETSC_COMM_WORLD,"After vectors - - - - - - - - -\n");
    102:     DSView(ds,viewer);
    103:   }

    105:   PetscFree(eig);
    106:   DSDestroy(&ds);
    107:   SlepcFinalize();
    108:   return ierr;
    109: }

    111: /*TEST

    113:    test:
    114:       suffix: 1
    115:       args: -n 12 -ds_method {{0 1 2}}
    116:       filter: grep -v "solving the problem"
    117:       requires: !single

    119: TEST*/