Actual source code: test4.c

slepc-3.7.1 2016-05-27
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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[] = "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: }