Thanks, this looks much prettier! 在 2018年3月27日星期二 UTC-7下午5:04:18，Jean-Paul Pelteret写道： > > Dear Weixiong, > > There’s an interpolation function that should do this for you: > > https://dealii.org/8.5.1/doxygen/deal.II/namespaceVectorTools.html#a5e3af70a47cedfaf361cf5c621e94e3d > The associated interpolation matrix is (I’m pretty sure) built using > > https://dealii.org/8.5.1/doxygen/deal.II/namespaceFETools.html#ab1e885987df913c64885ece9034b5c44 > > I hope this helps. If be interested to know if this gives you the same > result as your hand computation. > > Best, > Jean-Paul > > > On 28 Mar 2018, at 01:10, Weixiong Zheng <zwxn...@gmail.com <javascript:>> > wrote: > > I put my non-smart solution here in case if there's no easy way of doing > it in deal.II and someone else needs it. > > // The vector I want to output is the solution for vector-valued problem. > // I want to output the cell-average value for the 0th component. > Vector<double> modi (solu); > Quadrature<dim> qq(fe.get_unit_support_points()); > FEValues<dim> fv(fe, qq, update_values | update_quadrature_points); > std::vector<bool> selected_dofs (dof_handler.n_dofs()); > > // comp[0] is the 0th component of std::vector<FEValuesExtractors::Scalar> > for the system > DoFTools::extract_dofs(dof_handler, fe.component_mask(comp[0]), > selected_dofs); > std::vector<types::global_dof_index> local_to_global_dof (fe.dofs_per_cell > ); > > > // modify the 0th component > for (typename DoFHandler<dim>::active_cell_iterator > cell=dof_handler.begin_active(); cell!=dof_handler.end(); ++cell) { > fv.reinit(cell); > std::vector<double> local_sol(qq.size()); > fv[comp[0]].get_function_values(solu_out,local_sol); > double avg = std::accumulate(local_sol.begin(), local_sol.end(), 0.) / > local_sol.size(); > cell->get_dof_indices (local_to_global_dof); > for (auto i=0; i<fe.dofs_per_cell; ++i) { > if (selected_dofs[local_to_global_dof[i]]) { > solu_out[local_to_global_dof[i]] = avg; > } > } > } > > > If anyone has any smarter idea, please let me know and thanks in advance. > Weixiong > > 在 2018年3月27日星期二 UTC-7下午2:35:37，Weixiong Zheng写道： >> >> Hi >> >> I am trying to output an cell average solution for a code using DG >> bilinear element in 2D. Is there a trivial way to project DG-1 to DG-0? Or >> is there any function I can call to output the solution at some specfic >> points, say the center point of the cell? >> >> Thanks >> > > -- > 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+un...@googlegroups.com <javascript:>. > For more options, visit https://groups.google.com/d/optout. > > >
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