Date: 2017-05-17T08:27:37+00:00

Actual source code: test1.c
slepc-3.7.4 2017-05-17
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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[] = "Computes exp(A)*v for a matrix loaded from file.\n\n"
     23:   "The command line options are:\n"
     24:   "  -file <filename>, where <filename> = matrix file in PETSc binary form.\n\n";

     26: #include <slepcmfn.h>

     30: int main(int argc,char **argv)
     31: {
     32:   Mat                A;           /* problem matrix */
     33:   MFN                mfn;
     34:   FN                 f;
     35:   PetscReal          norm;
     36:   PetscScalar        t=2.0;
     37:   Vec                v,y;
     38:   PetscErrorCode     ierr;
     39:   PetscViewer        viewer;
     40:   PetscBool          flg;
     41:   char               filename[PETSC_MAX_PATH_LEN];
     42:   MFNConvergedReason reason;

     44:   SlepcInitialize(&argc,&argv,(char*)0,help);

     46:   PetscOptionsGetScalar(NULL,NULL,"-t",&t,NULL);
     47:   PetscPrintf(PETSC_COMM_WORLD,"\nMatrix exponential y=exp(t*A)*e, loaded from file\n\n");

     49:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     50:                 Load matrix A from binary file
     51:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     53:   PetscOptionsGetString(NULL,NULL,"-file",filename,PETSC_MAX_PATH_LEN,&flg);
     54:   if (!flg) SETERRQ(PETSC_COMM_WORLD,1,"Must indicate a file name with the -file option");

     56: #if defined(PETSC_USE_COMPLEX)
     57:   PetscPrintf(PETSC_COMM_WORLD," Reading COMPLEX matrix from a binary file...\n");
     58: #else
     59:   PetscPrintf(PETSC_COMM_WORLD," Reading REAL matrix from a binary file...\n");
     60: #endif
     61:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer);
     62:   MatCreate(PETSC_COMM_WORLD,&A);
     63:   MatSetFromOptions(A);
     64:   MatLoad(A,viewer);
     65:   PetscViewerDestroy(&viewer);

     67:   /* set v = ones(n,1) */
     68:   MatCreateVecs(A,NULL,&y);
     69:   MatCreateVecs(A,NULL,&v);
     70:   VecSet(v,1.0);

     72:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     73:                 Create the solver and set various options
     74:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     76:   MFNCreate(PETSC_COMM_WORLD,&mfn);
     77:   MFNSetOperator(mfn,A);
     78:   MFNGetFN(mfn,&f);
     79:   FNSetType(f,FNEXP);
     80:   FNSetScale(f,t,1.0);
     81:   MFNSetFromOptions(mfn);

     83:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     84:                       Solve the problem, y=exp(t*A)*v
     85:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     87:   MFNSolve(mfn,v,y);
     88:   MFNGetConvergedReason(mfn,&reason);
     89:   if (reason<0) SETERRQ(PETSC_COMM_WORLD,1,"Solver did not converge");
     90:   VecNorm(y,NORM_2,&norm);
     91:   PetscPrintf(PETSC_COMM_WORLD," Computed vector at time t=%.4g has norm %g\n\n",(double)PetscRealPart(t),(double)norm);
     92:
     93:   /*
     94:      Free work space
     95:   */
     96:   MFNDestroy(&mfn);
     97:   MatDestroy(&A);
     98:   VecDestroy(&v);
     99:   VecDestroy(&y);
    100:   SlepcFinalize();
    101:   return ierr;
    102: }