Actual source code: test2.c

  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2011, Universitat Politecnica de Valencia, Spain

  6:    This file is part of SLEPc.
  7:       
  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=1000*PETSC_MACHINE_EPSILON;
 34:   PetscScalar    value[3];
 35:   PetscInt       n=30,i,Istart,Iend,col[3];
 36:   PetscBool      FirstBlock=PETSC_FALSE,LastBlock=PETSC_FALSE,flg;

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

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

 44:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 45:      Compute the operator matrix that defines the eigensystem, Ax=kx
 46:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 48:   MatCreate(PETSC_COMM_WORLD,&A);
 49:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
 50:   MatSetFromOptions(A);
 51: 
 52:   MatGetOwnershipRange(A,&Istart,&Iend);
 53:   if (Istart==0) FirstBlock=PETSC_TRUE;
 54:   if (Iend==n) LastBlock=PETSC_TRUE;
 55:   value[0]=-1.0; value[1]=2.0; value[2]=-1.0;
 56:   for (i=(FirstBlock? Istart+1: Istart); i<(LastBlock? Iend-1: Iend); i++) {
 57:     col[0]=i-1; col[1]=i; col[2]=i+1;
 58:     MatSetValues(A,1,&i,3,col,value,INSERT_VALUES);
 59:   }
 60:   if (LastBlock) {
 61:     i=n-1; col[0]=n-2; col[1]=n-1;
 62:     MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
 63:   }
 64:   if (FirstBlock) {
 65:     i=0; col[0]=0; col[1]=1; value[0]=2.0; value[1]=-1.0;
 66:     MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
 67:   }

 69:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 70:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 72:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 73:                         Create the eigensolver
 74:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 75:   EPSCreate(PETSC_COMM_WORLD,&eps);
 76:   EPSSetOperators(eps,A,PETSC_NULL);
 77:   EPSSetProblemType(eps,EPS_HEP);
 78:   EPSSetTolerances(eps,tol,PETSC_DECIDE);
 79:   EPSSetFromOptions(eps);

 81:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 82:                     Solve for largest eigenvalues
 83:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 84:   EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL);
 85:   EPSSolve(eps);
 86:   PetscPrintf(PETSC_COMM_WORLD," - - - Largest eigenvalues - - -\n");
 87:   EPSPrintSolution(eps,PETSC_NULL);

 89:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 90:                     Solve for smallest eigenvalues
 91:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 92:   EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
 93:   EPSSolve(eps);
 94:   PetscPrintf(PETSC_COMM_WORLD," - - - Smallest eigenvalues - - -\n");
 95:   EPSPrintSolution(eps,PETSC_NULL);
 96: 
 97:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 98:                     Solve for interior eigenvalues (target=2.1)
 99:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
100:   EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE);
101:   EPSSetTarget(eps,2.1);
102:   PetscTypeCompare((PetscObject)eps,EPSLANCZOS,&flg);
103:   if (flg) {
104:     EPSGetST(eps,&st);
105:     STSetType(st,STSINVERT);
106:   } else {
107:     PetscTypeCompare((PetscObject)eps,EPSKRYLOVSCHUR,&flg);
108:     if (!flg) {
109:       PetscTypeCompare((PetscObject)eps,EPSARNOLDI,&flg);
110:     }
111:     if (flg) {
112:       EPSSetExtraction(eps,EPS_HARMONIC);
113:     }
114:   }
115:   EPSSolve(eps);
116:   PetscPrintf(PETSC_COMM_WORLD," - - - Interior eigenvalues - - -\n");
117:   EPSPrintSolution(eps,PETSC_NULL);
118: 
119:   EPSDestroy(&eps);
120:   MatDestroy(&A);
121:   SlepcFinalize();
122:   return 0;
123: }