Date: 2024-09-25T09:33:28+00:00

Actual source code: test16.c
slepc-3.21.2 2024-09-25
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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 a user-defined convergence test.\n\n";

     13: #include <slepceps.h>

     15: /*
     16:   MyConvergedAbsolute - Bizarre convergence test that requires more accuracy
     17:   to positive eigenvalues compared to negative ones.
     18: */
     19: PetscErrorCode MyConvergedAbsolute(EPS eps,PetscScalar eigr,PetscScalar eigi,PetscReal res,PetscReal *errest,void *ctx)
     20: {
     21:   PetscFunctionBegin;
     22:   *errest = (PetscRealPart(eigr)<0.0)?res:100*res;
     23:   PetscFunctionReturn(PETSC_SUCCESS);
     24: }

     26: int main(int argc,char **argv)
     27: {
     28:   Mat            A;           /* problem matrix */
     29:   EPS            eps;         /* eigenproblem solver context */
     30:   PetscInt       n=30,i,Istart,Iend;

     32:   PetscFunctionBeginUser;
     33:   PetscCall(SlepcInitialize(&argc,&argv,(char*)0,help));
     34:   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
     35:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nTridiagonal Eigenproblem, n=%" PetscInt_FMT "\n\n",n));

     37:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     38:      Compute the operator matrix that defines the eigensystem, Ax=kx
     39:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

     41:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
     42:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n));
     43:   PetscCall(MatSetFromOptions(A));

     45:   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
     46:   for (i=Istart;i<Iend;i++) {
     47:     if (i>0) PetscCall(MatSetValue(A,i,i-1,-1.0,INSERT_VALUES));
     48:     if (i<n-1) PetscCall(MatSetValue(A,i,i+1,-1.0,INSERT_VALUES));
     49:   }
     50:   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
     51:   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
     52:   PetscCall(MatShift(A,-1e-3));

     54:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     55:                         Create the eigensolver
     56:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     57:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
     58:   PetscCall(EPSSetOperators(eps,A,NULL));
     59:   PetscCall(EPSSetProblemType(eps,EPS_HEP));
     60:   /* set user-defined convergence test */
     61:   PetscCall(EPSSetConvergenceTestFunction(eps,MyConvergedAbsolute,NULL,NULL));
     62:   PetscCall(EPSSetFromOptions(eps));

     64:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     65:                           Solve the problem
     66:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
     67:   PetscCall(EPSSolve(eps));
     68:   PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));

     70:   PetscCall(EPSDestroy(&eps));
     71:   PetscCall(MatDestroy(&A));
     72:   PetscCall(SlepcFinalize());
     73:   return 0;
     74: }

     76: /*TEST

     78:    test:
     79:       suffix: 1
     80:       args: -n 200 -eps_nev 6 -eps_ncv 24 -eps_smallest_magnitude
     81:       requires: !single

     83: TEST*/