SLEPc Shift Invert

[Jonathan Russ]

Hello -

I was using step-36 as a starting place to write my own modal analysis code. In version 8.3.0 everything seemed to be working just fine, however since upgrading to 8.4.0 I get the following error (attached as an image) when I try to run the same code. I checked step-36 to be sure it is running correctly but it does not use the TransformationShiftInvert method in SLEPc that I require. Here is the snippet of my solver code that isn't working anymore.

 

 template <int dim>
  unsigned int EigenvalueProblem<dim>::solve ()
  {
     
    std::cout << "   Number of eigenvectors requested: "
              << eigenvectors.size() << std::endl;

    SolverControl solver_control (2000, 1e-9);
    SLEPcWrappers::SolverKrylovSchur eigensolver(solver_control);
    eigensolver.set_which_eigenpairs (EPS_SMALLEST_REAL);
    eigensolver.set_problem_type (EPS_GHEP);
   
    double eigen_shift = std::pow( 2.0 * PI * parameters.get_double ("Shift frequency"), 2.0);
    SLEPcWrappers::TransformationShiftInvert::AdditionalData additional_data(eigen_shift);
    SLEPcWrappers::TransformationShiftInvert shift (additional_data);
    eigensolver.set_transformation (shift);
     
    eigensolver.solve (stiffness_matrix,mass_matrix,eigenvalues,eigenvectors,
                       eigenvectors.size());

    for (unsigned int i=0; i<eigenvectors.size(); ++i)
      eigenvectors[i] /= eigenvectors[i].linfty_norm ();

    // Finally return the number of iterations it took to converge:
    return solver_control.last_step ();
  }

I do not wish to use MPI at this point. Is it still possible to invoke this solver in serial with only "additional_data" (no mpi_communicator)?

Thank you in advance for your help.

Jonathan

[Denis Davydov]

Hi Jonathan,

Between 8.3 and 8.4 the interface to spectral transformation changed, so that's why you have an error,

you can check the up-to-date documentation here: https://www.dealii.org/developer/doxygen/deal.II/classSLEPcWrappers_1_1TransformationShiftInvert.html

That has to do that now Spectral transformation classes initialize the underlying SLEPc objects straight away,

and to that end SLEPc needs MPI communicator irrespectively of MPI or no-MPI run:

http://slepc.upv.es/documentation/current/docs/manualpages/ST/STCreate.html

For serial case without MPI, i guess you can just pass PETSC_COMM_SELF or PETSC_COMM_WORLD,

You may still need to run in your main()

Utilities::MPI::MPI_InitFinalize mpi_initialization (argc, argv, 1);

Regards,

Denis.

[Toni Vidal]

Hi Jonathan,

Some functions in the SLEPcWrappers now need to be passed a MPI_Comm to their constructor as TransformationShiftInvert (const MPI_Comm &mpi_communicator, const AdditionalData &data=AdditionalData()). So just pass it even you are working in serial.

    SLEPcWrappers::TransformationShiftInvert shift (MPI_COMM_WORLD, additional_data);

Note that in the step-36 only can be run in serial as it is said in its main.

AssertThrow(Utilities::MPI::n_mpi_processes(MPI_COMM_WORLD)==1,

ExcMessage("This program can only be run in serial, use ./step-36"));

El dijous, 12 maig de 2016 4:34:57 UTC+2, Jonathan Russ va escriure:

[Jonathan Russ]

Great! Thank you very much! That worked perfectly!