--- /dev/null
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2021 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE.md at
+// the top level directory of deal.II.
+//
+// ---------------------------------------------------------------------
+
+// Check that we can use FieldTransfer when multiple cells are changed from
+// FE_Nothing to FE_Q
+
+#include <deal.II/distributed/field_transfer.h>
+
+#include <deal.II/dofs/dof_handler.h>
+#include <deal.II/dofs/dof_tools.h>
+
+#include <deal.II/fe/fe_nothing.h>
+#include <deal.II/fe/fe_q.h>
+
+#include <deal.II/grid/grid_generator.h>
+#include <deal.II/grid/tria.h>
+#include <deal.II/grid/tria_iterator.h>
+
+#include <deal.II/hp/fe_collection.h>
+
+#include "../tests.h"
+
+// FieldTransfer with ghosted vector
+
+int
+main(int argc, char *argv[])
+{
+ Utilities::MPI::MPI_InitFinalize mpi_initialization(argc, argv, 1);
+
+ MPILogInitAll mpi_log;
+
+ parallel::distributed::Triangulation<2> triangulation(MPI_COMM_WORLD);
+ GridGenerator::hyper_cube(triangulation);
+ triangulation.refine_global(2);
+
+ hp::FECollection<2> fe_collection;
+ fe_collection.push_back(FE_Q<2>(1));
+ fe_collection.push_back(FE_Nothing<2>());
+
+ DoFHandler<2> dof_handler(triangulation);
+
+ // Assign FE_Nothing to half of the domain
+ for (auto cell : dof_handler.active_cell_iterators())
+ {
+ if (cell->is_locally_owned())
+ {
+ if (cell->center()[1] < 0.5)
+ {
+ cell->set_active_fe_index(0);
+ }
+ else
+ {
+ cell->set_active_fe_index(1);
+ }
+ }
+ }
+
+ dof_handler.distribute_dofs(fe_collection);
+
+ // Initialize solution
+ auto locally_relevant_dofs =
+ DoFTools::extract_locally_relevant_dofs(dof_handler);
+ LinearAlgebra::distributed::Vector<double> solution(
+ dof_handler.locally_owned_dofs(), locally_relevant_dofs, MPI_COMM_WORLD);
+ const double old_value = 1.;
+ for (unsigned int i = 0; i < solution.local_size(); ++i)
+ solution.local_element(i) = old_value;
+
+ {
+ std::stringstream ss;
+ solution.print(ss);
+ deallog << ss.str() << std::endl;
+ }
+
+ parallel::distributed::experimental::
+ FieldTransfer<2, LinearAlgebra::distributed::Vector<double>>
+ field_transfer(dof_handler);
+ // Assgin FE_Q to all the cells
+ for (auto cell : dof_handler.active_cell_iterators())
+ {
+ if (cell->is_locally_owned())
+ {
+ cell->set_future_fe_index(0);
+ }
+ }
+
+ triangulation.prepare_coarsening_and_refinement();
+
+ solution.update_ghost_values();
+ field_transfer.prepare_for_coarsening_and_refinement(solution, 1);
+
+ triangulation.execute_coarsening_and_refinement();
+
+ dof_handler.distribute_dofs(fe_collection);
+ const unsigned int dofs_per_cell =
+ dof_handler.get_fe_collection().max_dofs_per_cell();
+
+ AffineConstraints<double> affine_constraints;
+ const double new_value = 2.;
+
+ locally_relevant_dofs.clear();
+ locally_relevant_dofs = DoFTools::extract_locally_relevant_dofs(dof_handler);
+ LinearAlgebra::distributed::Vector<double> new_solution(
+ dof_handler.locally_owned_dofs(), locally_relevant_dofs, MPI_COMM_WORLD);
+ field_transfer.interpolate(new_value, affine_constraints, new_solution);
+
+ {
+ std::stringstream ss;
+ new_solution.print(ss);
+ deallog << ss.str() << std::endl;
+ }
+}
--- /dev/null
+
+DEAL:0::Process #0
+Local range: [0, 9), global size: 15
+Vector data:
+1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00
+
+DEAL:0::Process #0
+Local range: [0, 9), global size: 25
+Vector data:
+1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00
+
+
+DEAL:1::Process #1
+Local range: [9, 15), global size: 15
+Vector data:
+1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00
+
+DEAL:1::Process #1
+Local range: [9, 21), global size: 25
+Vector data:
+1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 1.000e+00 2.000e+00 2.000e+00 2.000e+00 2.000e+00 2.000e+00 2.000e+00
+
+
+
+DEAL:2::Process #2
+Local range: [15, 15), global size: 15
+Vector data:
+
+
+DEAL:2::Process #2
+Local range: [21, 25), global size: 25
+Vector data:
+2.000e+00 2.000e+00 2.000e+00 2.000e+00
+
+