Subversion Repositories slepc-dev

/*

   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

   SLEPc - Scalable Library for Eigenvalue Problem Computations

   Copyright (c) 2002-2010, Universidad Politecnica de Valencia, Spain

   This file is part of SLEPc.

   SLEPc is free software: you can redistribute it and/or modify it under  the

   terms of version 3 of the GNU Lesser General Public License as published by

   the Free Software Foundation.

   SLEPc  is  distributed in the hope that it will be useful, but WITHOUT  ANY

   WARRANTY;  without even the implied warranty of MERCHANTABILITY or  FITNESS

   FOR  A  PARTICULAR PURPOSE. See the GNU Lesser General Public  License  for

   more details.

   You  should have received a copy of the GNU Lesser General  Public  License

   along with SLEPc. If not, see <http://www.gnu.org/licenses/>.

   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

*/

static char help[] = "Solves a standard eigensystem Ax=kx with the matrix loaded from a file.\n"

  "This example works for both real and complex numbers.\n\n"

  "The command line options are:\n"

  "  -file <filename>, where <filename> = matrix file in PETSc binary form.\n\n";

#include <slepceps.h>

#undef __FUNCT__

#define __FUNCT__ "main"

int main(int argc,char **argv)

{

  Mat            A;               /* operator matrix */

  EPS            eps;             /* eigenproblem solver context */

  const EPSType  type;

  PetscReal      error,tol,re,im;

  PetscScalar    kr,ki;

  PetscInt       nev,maxit,i,its,nconv;

  char           filename[PETSC_MAX_PATH_LEN];

  PetscViewer    viewer;

  PetscBool      flg;

  PetscErrorCode ierr;

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

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

        Load the operator matrix that defines the eigensystem, Ax=kx

     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

  ierr = PetscPrintf(PETSC_COMM_WORLD,"\nEigenproblem stored in file.\n\n");CHKERRQ(ierr);

  ierr = PetscOptionsGetString(PETSC_NULL,"-file",filename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);

  if (!flg) {

    SETERRQ(PETSC_COMM_WORLD,1,"Must indicate a file name with the -file option.");

  }

#if defined(PETSC_USE_COMPLEX)

  ierr = PetscPrintf(PETSC_COMM_WORLD," Reading COMPLEX matrix from a binary file...\n");CHKERRQ(ierr);

#else

  ierr = PetscPrintf(PETSC_COMM_WORLD," Reading REAL matrix from a binary file...\n");CHKERRQ(ierr);

#endif

  ierr = PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer);CHKERRQ(ierr);

  ierr = MatCreate(PETSC_COMM_WORLD,&A);CHKERRQ(ierr);

  ierr = MatSetFromOptions(A);CHKERRQ(ierr);

  ierr = MatLoad(A,viewer);CHKERRQ(ierr);

  ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

                Create the eigensolver and set various options

     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

  /*

     Create eigensolver context

  */

  ierr = EPSCreate(PETSC_COMM_WORLD,&eps);CHKERRQ(ierr);

  /*

     Set operators. In this case, it is a standard eigenvalue problem

  */

  ierr = EPSSetOperators(eps,A,PETSC_NULL);CHKERRQ(ierr);

  /*

     Set solver parameters at runtime

  */

  ierr = EPSSetFromOptions(eps);CHKERRQ(ierr);

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

                      Solve the eigensystem

     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

  ierr = EPSSolve(eps);CHKERRQ(ierr);

  ierr = EPSGetIterationNumber(eps,&its);CHKERRQ(ierr);

  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of iterations of the method: %d\n",its);CHKERRQ(ierr);

  /*

     Optional: Get some information from the solver and display it

  */

  ierr = EPSGetType(eps,&type);CHKERRQ(ierr);

  ierr = PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);CHKERRQ(ierr);

  ierr = EPSGetDimensions(eps,&nev,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);

  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %d\n",nev);CHKERRQ(ierr);

  ierr = EPSGetTolerances(eps,&tol,&maxit);CHKERRQ(ierr);

  ierr = PetscPrintf(PETSC_COMM_WORLD," Stopping condition: tol=%.4g, maxit=%d\n",tol,maxit);CHKERRQ(ierr);

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

                    Display solution and clean up

     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

  /*

     Get number of converged eigenpairs

  */

  ierr = EPSGetConverged(eps,&nconv);CHKERRQ(ierr);

  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of converged approximate eigenpairs: %d\n\n",nconv);CHKERRQ(ierr);

  if (nconv>0) {

    /*

       Display eigenvalues and relative errors

    */

    ierr = PetscPrintf(PETSC_COMM_WORLD,

         "           k             ||Ax-kx||/||kx||\n"

         "  --------------------- ------------------\n");CHKERRQ(ierr);

    for (i=0;i<nconv;i++) {

      /*

         Get converged eigenpairs: i-th eigenvalue is stored in kr (real part) and

         ki (imaginary part)

      */

      ierr = EPSGetEigenpair(eps,i,&kr,&ki,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);

      /*

         Compute the relative error associated to each eigenpair

      */

      ierr = EPSComputeRelativeError(eps,i,&error);CHKERRQ(ierr);

#if defined(PETSC_USE_COMPLEX)

      re = PetscRealPart(kr);

      im = PetscImaginaryPart(kr);

#else

      re = kr;

      im = ki;

#endif

      if (im != 0.0) {

        ierr = PetscPrintf(PETSC_COMM_WORLD," % 6f %+6f i",re,im);CHKERRQ(ierr);

      } else {

        ierr = PetscPrintf(PETSC_COMM_WORLD,"       % 6f      ",re);CHKERRQ(ierr);

      }

      ierr = PetscPrintf(PETSC_COMM_WORLD," % 12g\n",error);CHKERRQ(ierr);

    }

    ierr = PetscPrintf(PETSC_COMM_WORLD,"\n");CHKERRQ(ierr);

  }

  /*

     Free work space

  */

  ierr = EPSDestroy(&eps);CHKERRQ(ierr);

  ierr = MatDestroy(&A);CHKERRQ(ierr);

  ierr = SlepcFinalize();CHKERRQ(ierr);

  return 0;

}