Date: 2017-05-17T08:26:17+00:00

Actual source code: test13.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[] = "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;

     34:   VecDot(xr,xref,rr);
     35:   *rr = PetscAbsScalar(*rr);
     36:   if (ri) *ri = 0.0;
     37:   return(0);
     38: }

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

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

     54:   PetscOptionsGetInt(NULL,NULL,"-n",&n,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);

     65:   MatGetOwnershipRange(A,&Istart,&Iend);
     66:   for (i=Istart;i<Iend;i++) {
     67:     if (i>0) { MatSetValue(A,i,i-1,-1.0,INSERT_VALUES); }
     68:     if (i<n-1) { MatSetValue(A,i,i+1,-1.0,INSERT_VALUES); }
     69:   }
     70:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
     71:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

     73:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     74:                         Create the eigensolver
     75:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     76:   EPSCreate(PETSC_COMM_WORLD,&eps);
     77:   EPSSetProblemType(eps,EPS_HEP);
     78:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);
     79:   EPSSetOperators(eps,A,NULL);
     80:   EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
     81:   EPSSetFromOptions(eps);

     83:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     84:                 Solve eigenproblem and store some solution
     85:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     86:   EPSSolve(eps);
     87:   MatCreateVecs(A,&sxr,NULL);
     88:   MatCreateVecs(A,&sxi,NULL);
     89:   EPSGetConverged(eps,&nconv);
     90:   if (nconv>0) {
     91:     EPSGetEigenpair(eps,0,&seigr,&seigi,sxr,sxi);
     92:     EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);

     94:     /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     95:                  Solve eigenproblem using an arbitrary selection
     96:        - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     97:     EPSSetArbitrarySelection(eps,MyArbitrarySelection,&sxr);
     98:     EPSSetWhichEigenpairs(eps,EPS_LARGEST_MAGNITUDE);
     99:     EPSSolve(eps);
    100:     EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
    101:   } else {
    102:     PetscPrintf(PETSC_COMM_WORLD,"Problem: no eigenpairs converged.\n");
    103:   }

    105:   EPSDestroy(&eps);
    106:   VecDestroy(&sxr);
    107:   VecDestroy(&sxi);
    108:   MatDestroy(&A);
    109:   SlepcFinalize();
    110:   return ierr;
    111: }