Daniel, DoFTools::dof_indices_with_subdomain_association returns the degrees of > freedom of all the cells that have the given subdomain id. For > parallel::distributed::Triangulation objects the subdomain id is the the > MPI rank and this is the only valid input. > In this case, the function simply returns all the degrees of freedom on > locally owned cells. If a finite element defines degrees of freedoms that > are associated with a face, these degrees of freedom are part of all the > IndexSet objects in case the face is located on the interface between two > subdomains. For a parallel::distributed::Triangulation object, these are > the degrees of freedom on the faces to ghosted cells
Thanks for the reply. Indeed the indices given by DoFHandler::locally_owned_dofs() and DoFTools::dof_indices_with_subdomain_association() are identical for FE_DGQ element. I have checked this in my code. You could still ask for the unit support points and figure out which of > them are geometrically on a given face. This is definitely possible, but would probably be inefficient if I code for it. Isn't there a function in DoFTools which does this? Because not marking all dofs of ghost cells as relevant will give much savings in communication, I was wondering if DoFTools already doesn't have an implementation for this. However, note that as soon as gradients are involved all the degrees of > freedom contribute to values on faces. I don't have much experience in parallel programming, but I think we can circumvent this by computing gradients at all dof locations in a subdomain and again only communicating data of dofs lying on subdomain interfaces. I might need some correction on this :). -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/a4133885-0eab-4ddc-8e58-3d9c3835ddaa%40googlegroups.com.
