Date: 2021-02-01T14:42:00+00:00

Actual source code: test13.c
slepc-3.14.2 2021-02-01
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2020, Universitat Politecnica de Valencia, Spain

      6:    This file is part of SLEPc.
      7:    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
      8:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      9: */

     11: static char help[] = "Test EPSSetArbitrarySelection.\n\n";

     13: #include <slepceps.h>

     15: PetscErrorCode MyArbitrarySelection(PetscScalar eigr,PetscScalar eigi,Vec xr,Vec xi,PetscScalar *rr,PetscScalar *ri,void *ctx)
     16: {
     17:   PetscErrorCode  ierr;
     18:   Vec             xref = *(Vec*)ctx;

     21:   VecDot(xr,xref,rr);
     22:   *rr = PetscAbsScalar(*rr);
     23:   if (ri) *ri = 0.0;
     24:   return(0);
     25: }

     27: int main(int argc,char **argv)
     28: {
     29:   Mat            A;           /* problem matrices */
     30:   EPS            eps;         /* eigenproblem solver context */
     31:   PetscScalar    seigr,seigi;
     32:   PetscReal      tol=1000*PETSC_MACHINE_EPSILON;
     33:   Vec            sxr,sxi;
     34:   PetscInt       n=30,i,Istart,Iend,nconv;

     37:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;

     39:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     40:   PetscPrintf(PETSC_COMM_WORLD,"\nTridiagonal with zero diagonal, n=%D\n\n",n);

     42:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     43:            Create matrix tridiag([-1 0 -1])
     44:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     45:   MatCreate(PETSC_COMM_WORLD,&A);
     46:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
     47:   MatSetFromOptions(A);
     48:   MatSetUp(A);

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

     58:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     59:                         Create the eigensolver
     60:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     61:   EPSCreate(PETSC_COMM_WORLD,&eps);
     62:   EPSSetProblemType(eps,EPS_HEP);
     63:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);
     64:   EPSSetOperators(eps,A,NULL);
     65:   EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
     66:   EPSSetFromOptions(eps);

     68:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     69:                 Solve eigenproblem and store some solution
     70:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     71:   EPSSolve(eps);
     72:   MatCreateVecs(A,&sxr,NULL);
     73:   MatCreateVecs(A,&sxi,NULL);
     74:   EPSGetConverged(eps,&nconv);
     75:   if (nconv>0) {
     76:     EPSGetEigenpair(eps,0,&seigr,&seigi,sxr,sxi);
     77:     EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);

     79:     /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     80:                  Solve eigenproblem using an arbitrary selection
     81:        - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     82:     EPSSetArbitrarySelection(eps,MyArbitrarySelection,&sxr);
     83:     EPSSetWhichEigenpairs(eps,EPS_LARGEST_MAGNITUDE);
     84:     EPSSolve(eps);
     85:     EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
     86:   } else {
     87:     PetscPrintf(PETSC_COMM_WORLD,"Problem: no eigenpairs converged.\n");
     88:   }

     90:   EPSDestroy(&eps);
     91:   VecDestroy(&sxr);
     92:   VecDestroy(&sxi);
     93:   MatDestroy(&A);
     94:   SlepcFinalize();
     95:   return ierr;
     96: }

     98: /*TEST

    100:    testset:
    101:       args: -eps_max_it 5000 -st_pc_type jacobi
    102:       output_file: output/test13_1.out
    103:       test:
    104:          suffix: 1
    105:          args: -eps_type {{krylovschur gd jd}}
    106:       test:
    107:          suffix: 1_gd2
    108:          args: -eps_type gd -eps_gd_double_expansion
    109:       test:
    110:          suffix: 2
    111:          args: -eps_non_hermitian -eps_type {{krylovschur gd jd}}
    112:       test:
    113:          suffix: 2_gd2
    114:          args: -eps_non_hermitian -eps_type gd -eps_gd_double_expansion
    115:          timeoutfactor: 2

    117: TEST*/