Actual source code: test20.c

slepc-3.17.0 2022-03-31
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  1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-, 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;

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

 26:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 27:      Compute the operator matrix that defines the eigensystem, Ax=kx
 28:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

 43:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 44:              Create the solver, call EPSSolve() twice
 45:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 46:   EPSCreate(PETSC_COMM_WORLD,&eps);
 47:   EPSSetOperators(eps,A,NULL);
 48:   EPSSetProblemType(eps,EPS_HEP);
 49:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);
 50:   EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
 51:   EPSSetFromOptions(eps);

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

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

 65:   EPSDestroy(&eps);
 66:   MatDestroy(&A);
 67:   SlepcFinalize();
 68:   return 0;
 69: }

 71: /*TEST

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

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

 83: TEST*/