Actual source code: test2.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[] = "Tests multiple calls to EPSSolve with the same matrix.\n\n";

 24: #include <slepceps.h>

 28: int main(int argc,char **argv)
 29: {
 30:   Mat            A;           /* problem matrix */
 31:   EPS            eps;         /* eigenproblem solver context */
 32:   ST             st;
 33:   PetscReal      tol=PetscMax(1000*PETSC_MACHINE_EPSILON,1e-9);
 34:   PetscInt       n=30,i,Istart,Iend;
 35:   PetscBool      flg;

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

 40:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 41:   PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian Eigenproblem, n=%D\n\n",n);

 43:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 44:      Compute the operator matrix that defines the eigensystem, Ax=kx
 45:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 47:   MatCreate(PETSC_COMM_WORLD,&A);
 48:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
 49:   MatSetFromOptions(A);
 50:   MatSetUp(A);

 52:   MatGetOwnershipRange(A,&Istart,&Iend);
 53:   for (i=Istart;i<Iend;i++) {
 54:     if (i>0) { MatSetValue(A,i,i-1,-1.0,INSERT_VALUES); }
 55:     if (i<n-1) { MatSetValue(A,i,i+1,-1.0,INSERT_VALUES); }
 56:     MatSetValue(A,i,i,2.0,INSERT_VALUES);
 57:   }
 58:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 59:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 61:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 62:                         Create the eigensolver
 63:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 64:   EPSCreate(PETSC_COMM_WORLD,&eps);
 65:   EPSSetOperators(eps,A,NULL);
 66:   EPSSetProblemType(eps,EPS_HEP);
 67:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);
 68:   EPSSetFromOptions(eps);

 70:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 71:                     Solve for largest eigenvalues
 72:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 73:   EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL);
 74:   EPSSolve(eps);
 75:   PetscPrintf(PETSC_COMM_WORLD," - - - Largest eigenvalues - - -\n");
 76:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);

 78:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 79:                     Solve for smallest eigenvalues
 80:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 81:   EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
 82:   EPSSolve(eps);
 83:   PetscPrintf(PETSC_COMM_WORLD," - - - Smallest eigenvalues - - -\n");
 84:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);

 86:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 87:                     Solve for interior eigenvalues (target=2.1)
 88:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 89:   EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE);
 90:   EPSSetTarget(eps,2.1);
 91:   PetscObjectTypeCompare((PetscObject)eps,EPSLANCZOS,&flg);
 92:   if (flg) {
 93:     EPSGetST(eps,&st);
 94:     STSetType(st,STSINVERT);
 95:   } else {
 96:     PetscObjectTypeCompare((PetscObject)eps,EPSKRYLOVSCHUR,&flg);
 97:     if (!flg) {
 98:       PetscObjectTypeCompare((PetscObject)eps,EPSARNOLDI,&flg);
 99:     }
100:     if (flg) {
101:       EPSSetExtraction(eps,EPS_HARMONIC);
102:     }
103:   }
104:   EPSSolve(eps);
105:   PetscPrintf(PETSC_COMM_WORLD," - - - Interior eigenvalues - - -\n");
106:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);

108:   EPSDestroy(&eps);
109:   MatDestroy(&A);
110:   SlepcFinalize();
111:   return ierr;
112: }