Date: 2015-09-03T15:03:51+00:00

Actual source code: test3.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 matrix exponential.\n\n";

     24: #include <slepcfn.h>

     28: int main(int argc,char **argv)
     29: {
     31:   FN             fn;
     32:   Mat            A,B;
     33:   PetscInt       i,j,n=10;
     34:   PetscReal      nrm;
     35:   PetscScalar    *As,tau=1.0,eta=1.0;
     36:   PetscViewer    viewer;
     37:   PetscBool      verbose;

     39:   SlepcInitialize(&argc,&argv,(char*)0,help);
     40:   PetscOptionsGetInt(NULL,"-n",&n,NULL);
     41:   PetscOptionsGetScalar(NULL,"-tau",&tau,NULL);
     42:   PetscOptionsGetScalar(NULL,"-eta",&eta,NULL);
     43:   PetscOptionsHasName(NULL,"-verbose",&verbose);
     44:   PetscPrintf(PETSC_COMM_WORLD,"Matrix exponential, n=%D.\n",n);

     46:   /* Create exponential function eta*exp(tau*x) */
     47:   FNCreate(PETSC_COMM_WORLD,&fn);
     48:   FNSetType(fn,FNEXP);
     49:   FNSetScale(fn,tau,eta);

     51:   /* Set up viewer */
     52:   PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);
     53:   FNView(fn,viewer);
     54:   if (verbose) {
     55:     PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);
     56:   }

     58:   /* Create matrices */
     59:   MatCreateSeqDense(PETSC_COMM_SELF,n,n,NULL,&A);
     60:   PetscObjectSetName((PetscObject)A,"A");
     61:   MatCreateSeqDense(PETSC_COMM_SELF,n,n,NULL,&B);
     62:   PetscObjectSetName((PetscObject)B,"B");

     64:   /* Fill A with a symmetric Toeplitz matrix */
     65:   MatDenseGetArray(A,&As);
     66:   for (i=0;i<n;i++) As[i+i*n]=2.0;
     67:   for (j=1;j<3;j++) {
     68:     for (i=0;i<n-j;i++) { As[i+(i+j)*n]=1.0; As[(i+j)+i*n]=1.0; }
     69:   }
     70:   MatDenseRestoreArray(A,&As);
     71:   MatSetOption(A,MAT_HERMITIAN,PETSC_TRUE);
     72:   if (verbose) {
     73:     PetscPrintf(PETSC_COMM_WORLD,"Matrix A - - - - - - - -\n");
     74:     MatView(A,viewer);
     75:   }

     77:   /* Compute matrix exponential */
     78:   FNEvaluateFunctionMat(fn,A,B);
     79:   if (verbose) {
     80:     PetscPrintf(PETSC_COMM_WORLD,"Computed f(A) - - - - - - -\n");
     81:     MatView(B,viewer);
     82:   }
     83:   MatNorm(B,NORM_1,&nrm);
     84:   PetscPrintf(PETSC_COMM_WORLD,"The 1-norm of f(A) is %g\n",(double)nrm);

     86:   /* Repeat with non-symmetric A */
     87:   MatDenseGetArray(A,&As);
     88:   for (j=1;j<3;j++) {
     89:     for (i=0;i<n-j;i++) { As[(i+j)+i*n]=-1.0; }
     90:   }
     91:   MatDenseRestoreArray(A,&As);
     92:   MatSetOption(A,MAT_HERMITIAN,PETSC_FALSE);
     93:   if (verbose) {
     94:     PetscPrintf(PETSC_COMM_WORLD,"Matrix A - - - - - - - -\n");
     95:     MatView(A,viewer);
     96:   }

     98:   /* Compute matrix exponential */
     99:   FNEvaluateFunctionMat(fn,A,B);
    100:   if (verbose) {
    101:     PetscPrintf(PETSC_COMM_WORLD,"Computed f(A) - - - - - - -\n");
    102:     MatView(B,viewer);
    103:   }
    104:   MatNorm(B,NORM_1,&nrm);
    105:   PetscPrintf(PETSC_COMM_WORLD,"The 1-norm of f(A) is %g\n",(double)nrm);

    107:   MatDestroy(&A);
    108:   MatDestroy(&B);
    109:   FNDestroy(&fn);
    110:   SlepcFinalize();
    111:   return 0;
    112: }