Date: 2024-12-02T08:58:24+00:00

Actual source code: test12.c
slepc-3.22.2 2024-12-02
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-, 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 matrix function evaluation via diagonalization.\n\n";

     13: #include <slepcfn.h>

     15: int main(int argc,char **argv)
     16: {
     17:   FN             fn;
     18:   Mat            A,F,G;
     19:   PetscInt       i,j,n=10;
     20:   PetscReal      nrm;
     21:   PetscScalar    *As,alpha,beta;
     22:   PetscViewer    viewer;
     23:   PetscBool      verbose;

     25:   PetscFunctionBeginUser;
     26:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
     27:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     28:   PetscCall(PetscOptionsHasName(NULL,NULL,"-verbose",&verbose));
     29:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Matrix function of symmetric/Hermitian matrix, n=%" PetscInt_FMT ".\n",n));

     31:   /* Create function object */
     32:   PetscCall(FNCreate(PETSC_COMM_WORLD,&fn));
     33:   PetscCall(FNSetType(fn,FNEXP));   /* default to exponential */
     34: #if defined(PETSC_USE_COMPLEX)
     35:   alpha = PetscCMPLX(0.3,0.8);
     36:   beta  = PetscCMPLX(1.1,-0.1);
     37: #else
     38:   alpha = 0.3;
     39:   beta  = 1.1;
     40: #endif
     41:   PetscCall(FNSetScale(fn,alpha,beta));
     42:   PetscCall(FNSetFromOptions(fn));

     44:   /* Set up viewer */
     45:   PetscCall(PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer));
     46:   if (verbose) PetscCall(PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB));

     48:   /* Create a symmetric/Hermitian Toeplitz matrix */
     49:   PetscCall(MatCreateSeqDense(PETSC_COMM_SELF,n,n,NULL,&A));
     50:   PetscCall(PetscObjectSetName((PetscObject)A,"A"));
     51:   PetscCall(MatDenseGetArray(A,&As));
     52:   for (i=0;i<n;i++) As[i+i*n]=2.0;
     53:   for (j=1;j<3;j++) {
     54:     for (i=0;i<n-j;i++) {
     55: #if defined(PETSC_USE_COMPLEX)
     56:       As[i+(i+j)*n]=PetscCMPLX(1.0,0.1); As[(i+j)+i*n]=PetscCMPLX(1.0,-0.1);
     57: #else
     58:       As[i+(i+j)*n]=0.5; As[(i+j)+i*n]=0.5;
     59: #endif
     60:     }
     61:   }
     62:   PetscCall(MatDenseRestoreArray(A,&As));
     63:   if (verbose) {
     64:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Matrix A - - - - - - - -\n"));
     65:     PetscCall(MatView(A,viewer));
     66:   }

     68:   /* compute matrix function */
     69:   PetscCall(MatCreateSeqDense(PETSC_COMM_SELF,n,n,NULL,&F));
     70:   PetscCall(PetscObjectSetName((PetscObject)F,"F"));
     71:   PetscCall(FNEvaluateFunctionMat(fn,A,F));
     72:   if (verbose) {
     73:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Computed f(A) - - - - - - -\n"));
     74:     PetscCall(MatView(F,viewer));
     75:   }

     77:   /* Repeat with MAT_HERMITIAN flag set */
     78:   PetscCall(MatSetOption(A,MAT_HERMITIAN,PETSC_TRUE));
     79:   PetscCall(MatCreateSeqDense(PETSC_COMM_SELF,n,n,NULL,&G));
     80:   PetscCall(PetscObjectSetName((PetscObject)G,"G"));
     81:   PetscCall(FNEvaluateFunctionMat(fn,A,G));
     82:   if (verbose) {
     83:     PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Computed f(A) symm - - - - - - -\n"));
     84:     PetscCall(MatView(G,viewer));
     85:   }

     87:   /* compare the two results */
     88:   PetscCall(MatAXPY(F,-1.0,G,SAME_NONZERO_PATTERN));
     89:   PetscCall(MatNorm(F,NORM_FROBENIUS,&nrm));
     90:   if (nrm>100*PETSC_MACHINE_EPSILON) PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Warning: the norm of F-G is %g\n",(double)nrm));
     91:   else PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Computed results match.\n"));

     93:   PetscCall(MatDestroy(&A));
     94:   PetscCall(MatDestroy(&F));
     95:   PetscCall(MatDestroy(&G));
     96:   PetscCall(FNDestroy(&fn));
     97:   PetscCall(SlepcFinalize());
     98:   return 0;
     99: }

    101: /*TEST

    103:    test:
    104:       suffix: 1
    105:       nsize: 1
    106:       args: -fn_type {{exp sqrt}shared output}
    107:       output_file: output/test12_1.out

    109:    test:
    110:       suffix: 1_rational
    111:       nsize: 1
    112:       args: -fn_type rational -fn_rational_numerator 2,-1.5 -fn_rational_denominator 1,0.8
    113:       output_file: output/test12_1.out

    115: TEST*/