Date: 2013-09-02T10:05:22+00:00

Actual source code: test4.c

      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2013, 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:   PetscScalar    value[3];
     38:   PetscInt       n=30,i,Istart,Iend,col[3],nev;
     39:   PetscBool      FirstBlock=PETSC_FALSE,LastBlock=PETSC_FALSE,isgd2;
     40:   char           epstype[30] = "krylovschur";

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

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

     50:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     51:      Compute the operator matrix that defines the eigensystem, Ax=kx
     52:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

     59:   MatGetOwnershipRange(A,&Istart,&Iend);
     60:   if (Istart==0) FirstBlock=PETSC_TRUE;
     61:   if (Iend==n) LastBlock=PETSC_TRUE;
     62:   value[0]=-1.0; value[1]=2.0; value[2]=-1.0;
     63:   for (i=(FirstBlock? Istart+1: Istart); i<(LastBlock? Iend-1: Iend); i++) {
     64:     col[0]=i-1; col[1]=i; col[2]=i+1;
     65:     MatSetValues(A,1,&i,3,col,value,INSERT_VALUES);
     66:   }
     67:   if (LastBlock) {
     68:     i=n-1; col[0]=n-2; col[1]=n-1;
     69:     MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
     70:   }
     71:   if (FirstBlock) {
     72:     i=0; col[0]=0; col[1]=1; value[0]=2.0; value[1]=-1.0;
     73:     MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
     74:   }

     76:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
     77:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

     79:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     80:                 Create the eigensolver and set various options
     81:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     82:   /*
     83:      Create eigensolver context
     84:   */
     85:   EPSCreate(PETSC_COMM_WORLD,&eps);

     87:   /*
     88:      Set operators. In this case, it is a standard eigenvalue problem
     89:   */
     90:   EPSSetOperators(eps,A,NULL);
     91:   EPSSetProblemType(eps,EPS_HEP);
     92:   EPSSetDimensions(eps,4,PETSC_DEFAULT,PETSC_DEFAULT);
     93:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);

     95:   /*
     96:      Set solver parameters at runtime
     97:   */
     98:   PetscStrcmp(epstype,"gd2",&isgd2);
     99:   if (isgd2) {
    100:     EPSSetType(eps,EPSGD);
    101:     EPSGDSetDoubleExpansion(eps,PETSC_TRUE);
    102:   } else {
    103:     EPSSetType(eps,epstype);
    104:   }

    106:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    107:                       Solve the eigensystem
    108:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    110:   EPSSolve(eps);
    111:   /*
    112:      Optional: Get some information from the solver and display it
    113:   */
    114:   EPSGetType(eps,&type);
    115:   PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);
    116:   EPSGetDimensions(eps,&nev,NULL,NULL);
    117:   PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %D\n",nev);

    119:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    120:                     Display solution and clean up
    121:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

    123:   EPSPrintSolution(eps,NULL);
    124:   EPSDestroy(&eps);
    125:   MatDestroy(&A);
    126:   SlepcFinalize();
    127:   return 0;
    128: }