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

Actual source code: test20.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[] = "Tests multiple calls to EPSSolve changing ncv.\n\n";

     13: #include <slepceps.h>

     15: int main(int argc,char **argv)
     16: {
     17:   Mat            A;
     18:   EPS            eps;
     19:   PetscReal      tol=PetscMax(1000*PETSC_MACHINE_EPSILON,1e-9);
     20:   PetscInt       n=30,i,Istart,Iend,nev,ncv;

     23:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
     24:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
     25:   PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian Eigenproblem, n=%D\n\n",n);

     27:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     28:      Compute the operator matrix that defines the eigensystem, Ax=kx
     29:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     31:   MatCreate(PETSC_COMM_WORLD,&A);
     32:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
     33:   MatSetFromOptions(A);
     34:   MatSetUp(A);
     35:   MatGetOwnershipRange(A,&Istart,&Iend);
     36:   for (i=Istart;i<Iend;i++) {
     37:     if (i>0) { MatSetValue(A,i,i-1,-1.0,INSERT_VALUES); }
     38:     if (i<n-1) { MatSetValue(A,i,i+1,-1.0,INSERT_VALUES); }
     39:     MatSetValue(A,i,i,2.0,INSERT_VALUES);
     40:   }
     41:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
     42:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

     44:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     45:              Create the solver, call EPSSolve() twice
     46:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     47:   EPSCreate(PETSC_COMM_WORLD,&eps);
     48:   EPSSetOperators(eps,A,NULL);
     49:   EPSSetProblemType(eps,EPS_HEP);
     50:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);
     51:   EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
     52:   EPSSetFromOptions(eps);

     54:   /* First solve */
     55:   EPSSolve(eps);
     56:   PetscPrintf(PETSC_COMM_WORLD," - - - First solve, default subspace dimension - - -\n");
     57:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);

     59:   /* Second solve */
     60:   EPSGetDimensions(eps,&nev,&ncv,NULL);
     61:   EPSSetDimensions(eps,nev,ncv+2,PETSC_DEFAULT);
     62:   EPSSolve(eps);
     63:   PetscPrintf(PETSC_COMM_WORLD," - - - Second solve, subspace of increased size - - -\n");
     64:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);

     66:   EPSDestroy(&eps);
     67:   MatDestroy(&A);
     68:   SlepcFinalize();
     69:   return ierr;
     70: }

     72: /*TEST

     74:    test:
     75:       suffix: 1
     76:       args: -n 18 -eps_type {{krylovschur arnoldi gd jd rqcg lobpcg lapack}} -eps_max_it 1500
     77:       output_file: output/test20_1.out

     79:    test:
     80:       suffix: 1_lanczos
     81:       args: -n 18 -eps_type lanczos -eps_lanczos_reorthog full -eps_max_it 1500
     82:       output_file: output/test20_1.out

     84: TEST*/