Dear Michal, We do not offer convenience access for all data structures on faces yet, so feel free to suggest what you need.
That said, for the access of rho and mu on an element, we provide the following access function: https://www.dealii.org/current/doxygen/deal.II/classFEEvaluationBase.html#a442f1ee55e6e80a58e19d53c7184c1a7 This FEEvaluationBase::read_cell_data function expects an AlignedVector<VectorizedArray<Number>> as the argument with as many components as there are cell batches (plus ghosted ones for the MPI case). So in your code, you would fill the rho and mu fields by a cell loop (for MPI, please run it for "n_cells = this->data->n_macro_cells() + this->data->n_ghost_cell_batches()". Then you can access that data both on cells and faces, i.e., with FEEvaluation and FEFaceEvaluation. The implementation resolves the `interior_cells` and `exterior_cells` fields for you. Retrieving the `user_index` is a bit more involved as we do not provide access to a face iterator. You could do it approximately as follows (sitting on a face like in your code below): const unsigned int interior_cell = face2cell_info.cells_interior[element]; const Triangulation<dim>::cell_iterator my_cell = this->data->get_cell_iterator(interior_cell / VectorizedArray<Number>::n_array_elements, interior_cell % VectorizedArray<Number>::n_array_elements); const Triangulation<dim>::face_iterator face_it = my_cell->face(face2cell_info.interior_face_no); Can you try if that works? If yes, we should add some access functions to MatrixFree. Let us know if you are interested in helping with a pull request. Best, Martin On 05.08.19 19:34, Michał Wichrowski wrote: > Dear all, > I'm trying to use matrix-free with discontinuous Galerkin elements for > variable coefficient problem. The face integral require access to > value of coefficient. For the cell I've done the following thing: > //Vectors of values, stored in object: > AlignedVector< VectorizedArray<Number> > mu; > AlignedVector< VectorizedArray<Number> > rho; > //Filling the vectors: > const unsigned int n_cells = this->data->n_macro_cells(); > rho.resize (n_cells); > mu.resize (n_cells); > for (unsigned int cell=0; cell<n_cells; ++cell) > { > for(unsigned int element=0; > element<this->data->n_components_filled(cell) ; ++element){ > const unsigned int ID=this->data->get_cell_iterator(cell,element,0 > )->material_id(); > rho[cell][element] = rho_map.at(ID) ; > mu[cell][element] = miu_map.at(ID) ; > } > } > For the faces I am trying to do something like that: > //Vectors of values, stored in object: > AlignedVector< VectorizedArray<Number> > mu_inner_faces; > > //Filling the vectors: > const unsigned int n_faces=this->data->n_inner_face_batches(); > mu_inner_faces.resize(n_faces); > for (unsigned int face=0; face<n_faces; ++face){ > const internal::MatrixFreeFunctions::FaceToCellTopology > < VectorizedArray< Number >::n_array_elements > > face2cell_info=this->data->get_face_info(face); > > for(unsigned int element=0; > element<this->data->n_active_entries_per_face_batch(face) ; > ++element){ > const unsigned int interior_cell = > face2cell_info.cells_interior[element]; > const unsigned int exterior_cell = > face2cell_info.cells_exterior[element]; > > ?????????????????????????????????????? > > } > } > > If I understood correctly interior_cell and exterior_cell will be > numbers of cell. > I have no idea how to get cell iterators from that information. I > even found that MAtrixFree class contains attribute > std::vector< std::pair< unsigned int, unsigned int > > > cell_level_index > <https://dealii.org/current/doxygen/deal.II/classMatrixFree.html#acef3e0d7d294a05dca57f290583ba629> > > > but unfortunately it is private and there is no getter for that. > > I will also need to get user_index from each face and create from that > another AlignedVector of parameters. This operations will be done only > once so I do not care much about efficiency. > Best, > Michal > -- > 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 dealii+unsubscr...@googlegroups.com > <mailto:dealii+unsubscr...@googlegroups.com>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/b3c0fccd-7a76-4d90-a573-74719d281c37%40googlegroups.com > <https://groups.google.com/d/msgid/dealii/b3c0fccd-7a76-4d90-a573-74719d281c37%40googlegroups.com?utm_medium=email&utm_source=footer>. -- 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. 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