--- /dev/null
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2017 - 2018 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.
+//
+// ---------------------------------------------------------------------
+
+
+// Like the _05 test, just for tensor-valued quantities.
+
+#include <deal.II/base/logstream.h>
+
+#include <deal.II/dofs/dof_accessor.h>
+#include <deal.II/dofs/dof_handler.h>
+#include <deal.II/dofs/dof_tools.h>
+
+#include <deal.II/fe/fe_q.h>
+#include <deal.II/fe/fe_system.h>
+
+#include <deal.II/grid/grid_generator.h>
+#include <deal.II/grid/tria.h>
+#include <deal.II/grid/tria_iterator.h>
+
+#include <deal.II/lac/block_vector.h>
+#include <deal.II/lac/vector.h>
+
+#include <deal.II/numerics/data_out.h>
+
+#include <fstream>
+#include <iomanip>
+#include <string>
+
+#include "../tests.h"
+
+
+
+template <int dim>
+void
+check()
+{
+ Triangulation<dim> tria;
+ GridGenerator::hyper_cube(tria, 0., 1.);
+
+ // Create a vector-valued finite element
+ FESystem<dim> fe(FE_Q<dim>(1), dim * dim);
+ DoFHandler<dim> dof_handler(tria);
+ dof_handler.distribute_dofs(fe);
+
+ // Pick a special solution function: constant in space, but one
+ // where the individual tensor components have the form c-c*i
+ // (counting components from 1, for uniqueness of components). This
+ // allows us to check that the ordering of components in the output
+ // file is correct.
+ //
+ // For example, in 2d, the ordering of output components should then
+ // be
+ // [1 2 3 4] [-1 -2 -3 -4]
+ // where [...] indicates which components jointly form a tensor.
+ Vector<std::complex<double>> v(dof_handler.n_dofs());
+ for (unsigned int i = 0; i < v.size(); ++i)
+ v(i) = std::complex<double>(1, -1) * double(i % fe.n_components() + 1);
+
+ DataOut<dim> data_out;
+ data_out.attach_dof_handler(dof_handler);
+ data_out.add_data_vector(
+ v,
+ std::vector<std::string>(dim * dim, "tensor_field"),
+ DataOut<dim>::type_dof_data,
+ std::vector<DataComponentInterpretation::DataComponentInterpretation>(
+ dim * dim, DataComponentInterpretation::component_is_part_of_tensor));
+ data_out.build_patches();
+
+ data_out.write_gnuplot(deallog.get_file_stream());
+}
+
+
+
+int
+main()
+{
+ initlog();
+
+ try
+ {
+ check<1>();
+ check<2>();
+ check<3>();
+ }
+ catch (std::exception &exc)
+ {
+ deallog << std::endl
+ << std::endl
+ << "----------------------------------------------------"
+ << std::endl;
+ deallog << "Exception on processing: " << std::endl
+ << exc.what() << std::endl
+ << "Aborting!" << std::endl
+ << "----------------------------------------------------"
+ << std::endl;
+ return 1;
+ }
+ catch (...)
+ {
+ deallog << std::endl
+ << std::endl
+ << "----------------------------------------------------"
+ << std::endl;
+ deallog << "Unknown exception!" << std::endl
+ << "Aborting!" << std::endl
+ << "----------------------------------------------------"
+ << std::endl;
+ return 1;
+ }
+}
--- /dev/null
+
+# This file was generated by the deal.II library.
+
+
+#
+# For a description of the GNUPLOT format see the GNUPLOT manual.
+#
+# <x> <tensor_field_re> <tensor_field_im>
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+
+# This file was generated by the deal.II library.
+
+
+#
+# For a description of the GNUPLOT format see the GNUPLOT manual.
+#
+# <x> <y> <tensor_field_re> <tensor_field_re> <tensor_field_re> <tensor_field_re> <tensor_field_im> <tensor_field_im> <tensor_field_im> <tensor_field_im>
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+
+# This file was generated by the deal.II library.
+
+
+#
+# For a description of the GNUPLOT format see the GNUPLOT manual.
+#
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