Date: 2017-05-17T08:26:15+00:00

Actual source code: test4.c
slepc-3.7.4 2017-05-17
Report Typos and Errors

      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[] = "Test the solution of a HEP without calling EPSSetFromOptions (based on ex1.c).\n\n"
     23:   "The command line options are:\n"
     24:   "  -n <n>, where <n> = number of grid subdivisions = matrix dimension.\n"
     25:   "  -type <eps_type> = eps type to test.\n\n";

     27: #include <slepceps.h>

     31: int main(int argc,char **argv)
     32: {
     33:   Mat            A;           /* problem matrix */
     34:   EPS            eps;         /* eigenproblem solver context */
     35:   EPSType        type;
     36:   PetscReal      tol=1000*PETSC_MACHINE_EPSILON;
     37:   PetscInt       n=30,i,Istart,Iend,nev;
     38:   PetscBool      isgd2;
     39:   char           epstype[30] = "krylovschur";

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

     44:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     45:   PetscOptionsGetString(NULL,NULL,"-type",epstype,30,NULL);
     46:   PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian Eigenproblem, n=%D",n);
     47:   PetscPrintf(PETSC_COMM_WORLD,"\nEPS type: %s\n\n",epstype);

     49:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     50:      Compute the operator matrix that defines the eigensystem, Ax=kx
     51:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     53:   MatCreate(PETSC_COMM_WORLD,&A);
     54:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
     55:   MatSetFromOptions(A);
     56:   MatSetUp(A);

     58:   MatGetOwnershipRange(A,&Istart,&Iend);
     59:   for (i=Istart;i<Iend;i++) {
     60:     if (i>0) { MatSetValue(A,i,i-1,-1.0,INSERT_VALUES); }
     61:     if (i<n-1) { MatSetValue(A,i,i+1,-1.0,INSERT_VALUES); }
     62:     MatSetValue(A,i,i,2.0,INSERT_VALUES);
     63:   }
     64:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
     65:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

     67:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     68:                 Create the eigensolver and set various options
     69:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     70:   /*
     71:      Create eigensolver context
     72:   */
     73:   EPSCreate(PETSC_COMM_WORLD,&eps);

     75:   /*
     76:      Set operators. In this case, it is a standard eigenvalue problem
     77:   */
     78:   EPSSetOperators(eps,A,NULL);
     79:   EPSSetProblemType(eps,EPS_HEP);
     80:   EPSSetDimensions(eps,4,PETSC_DEFAULT,PETSC_DEFAULT);
     81:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);

     83:   /*
     84:      Set solver parameters at runtime
     85:   */
     86:   PetscStrcmp(epstype,"gd2",&isgd2);
     87:   if (isgd2) {
     88:     EPSSetType(eps,EPSGD);
     89:     EPSGDSetDoubleExpansion(eps,PETSC_TRUE);
     90:   } else {
     91:     EPSSetType(eps,epstype);
     92:   }

     94:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     95:                       Solve the eigensystem
     96:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     98:   EPSSolve(eps);
     99:   /*
    100:      Optional: Get some information from the solver and display it
    101:   */
    102:   EPSGetType(eps,&type);
    103:   PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);
    104:   EPSGetDimensions(eps,&nev,NULL,NULL);
    105:   PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %D\n",nev);

    107:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    108:                     Display solution and clean up
    109:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    111:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
    112:   EPSDestroy(&eps);
    113:   MatDestroy(&A);
    114:   SlepcFinalize();
    115:   return ierr;
    116: }