Actual source code: test13.c

  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-2012, 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[] = "Test EPSSetArbitrarySelection.\n\n";

 24: #include <slepceps.h>

 28: PetscErrorCode MyArbitrarySelection(PetscScalar eigr,PetscScalar eigi,Vec xr,Vec xi,PetscScalar *rr,PetscScalar *ri,void *ctx)
 29: {
 30:   PetscErrorCode  ierr;
 31:   Vec             xref = *(Vec*)ctx;
 33:   VecDot(xr,xref,rr);
 34:   *rr = PetscAbsScalar(*rr);
 35:   if (ri) *ri = 0.0;
 36:   return(0);
 37: }

 41: int main(int argc,char **argv)
 42: {
 43:   Mat            A;           /* problem matrices */
 44:   EPS            eps;         /* eigenproblem solver context */
 45:   PetscScalar    seigr,seigi,value[3];
 46:   PetscReal      tol=1000*PETSC_MACHINE_EPSILON;
 47:   Vec            sxr,sxi;
 48:   PetscInt       n=30,i,Istart,Iend,col[3],nconv;
 49:   PetscBool      FirstBlock=PETSC_FALSE,LastBlock=PETSC_FALSE;

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

 54:   PetscOptionsGetInt(PETSC_NULL,"-n",&n,PETSC_NULL);
 55:   PetscPrintf(PETSC_COMM_WORLD,"\nTridiagonal with zero diagonal, n=%D\n\n",n);

 57:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 58:            Create matrix tridiag([-1 0 -1])
 59:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 60:   MatCreate(PETSC_COMM_WORLD,&A);
 61:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
 62:   MatSetFromOptions(A);
 63:   MatSetUp(A);
 64: 
 65:   MatGetOwnershipRange(A,&Istart,&Iend);
 66:   if (Istart==0) FirstBlock=PETSC_TRUE;
 67:   if (Iend==n) LastBlock=PETSC_TRUE;
 68:   value[0]=-1.0; value[1]=0.0; value[2]=-1.0;
 69:   for (i=(FirstBlock? Istart+1: Istart); i<(LastBlock? Iend-1: Iend); i++) {
 70:     col[0]=i-1; col[1]=i; col[2]=i+1;
 71:     MatSetValues(A,1,&i,3,col,value,INSERT_VALUES);
 72:   }
 73:   if (LastBlock) {
 74:     i=n-1; col[0]=n-2; col[1]=n-1;
 75:     MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
 76:   }
 77:   if (FirstBlock) {
 78:     i=0; col[0]=0; col[1]=1; value[0]=0.0; value[1]=-1.0;
 79:     MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
 80:   }

 82:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 83:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 85:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 86:                         Create the eigensolver
 87:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 88:   EPSCreate(PETSC_COMM_WORLD,&eps);
 89:   EPSSetProblemType(eps,EPS_HEP);
 90:   EPSSetTolerances(eps,tol,PETSC_DECIDE);
 91:   EPSSetOperators(eps,A,PETSC_NULL);
 92:   EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
 93:   EPSSetFromOptions(eps);

 95:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 96:                 Solve eigenproblem and store some solution
 97:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 98:   EPSSolve(eps);
 99:   MatGetVecs(A,&sxr,PETSC_NULL);
100:   MatGetVecs(A,&sxi,PETSC_NULL);
101:   EPSGetConverged(eps,&nconv);
102:   if (nconv>0) {
103:     EPSGetEigenpair(eps,0,&seigr,&seigi,sxr,sxi);
104:     EPSPrintSolution(eps,PETSC_NULL);

106:     /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
107:                  Solve eigenproblem using an arbitrary selection
108:        - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
109:     EPSSetArbitrarySelection(eps,MyArbitrarySelection,&sxr);
110:     EPSSetWhichEigenpairs(eps,EPS_LARGEST_MAGNITUDE);
111:     EPSSolve(eps);
112:     EPSPrintSolution(eps,PETSC_NULL);
113:   } else {
114:     PetscPrintf(PETSC_COMM_WORLD,"Problem: no eigenpairs converged.\n");
115:   }
116: 
117:   EPSDestroy(&eps);
118:   VecDestroy(&sxr);
119:   VecDestroy(&sxi);
120:   MatDestroy(&A);
121:   SlepcFinalize();
122:   return 0;
123: }