--- /dev/null
+//---------------------------- interpolate_dgq_02.cc ---------------------------
+// $Id: interpolate_dgq_02.cc 12732 2006-03-28 23:15:45Z wolf $
+// Version: $Name$
+//
+// Copyright (C) 2006 by the deal.II authors
+//
+// This file is subject to QPL and may not be distributed
+// without copyright and license information. Please refer
+// to the file deal.II/doc/license.html for the text and
+// further information on this license.
+//
+//---------------------------- interpolate_dgq_02.cc ---------------------------
+
+
+// check that VectorTools::interpolate works for FE_DGQ(p) elements correctly on
+// an adaptively refined mesh for functions of degree q
+
+#include "../tests.h"
+#include <base/function.h>
+#include <base/logstream.h>
+#include <base/quadrature_lib.h>
+#include <lac/vector.h>
+
+#include <grid/tria.h>
+#include <dofs/dof_handler.h>
+#include <dofs/dof_tools.h>
+#include <dofs/dof_constraints.h>
+#include <grid/grid_generator.h>
+#include <grid/grid_refinement.h>
+#include <grid/tria_accessor.h>
+#include <grid/tria_iterator.h>
+#include <grid/tria_boundary_lib.h>
+#include <dofs/dof_accessor.h>
+#include <dofs/dof_tools.h>
+#include <numerics/vectors.h>
+#include <fe/fe_dgq.h>
+
+#include <fstream>
+#include <vector>
+
+
+template <int dim>
+class F : public Function<dim>
+{
+ public:
+ F (const unsigned int q) : q(q) {}
+
+ virtual double value (const Point<dim> &p,
+ const unsigned int) const
+ {
+ double v=0;
+ for (unsigned int d=0; d<dim; ++d)
+ for (unsigned int i=0; i<=q; ++i)
+ v += (d+1)*(i+1)*std::pow (p[d], 1.*i);
+ return v;
+ }
+
+ private:
+ const unsigned int q;
+};
+
+
+
+template <int dim>
+void test ()
+{
+ Triangulation<dim> triangulation;
+ GridGenerator::hyper_cube (triangulation);
+ triangulation.refine_global (1);
+ triangulation.begin_active()->set_refine_flag ();
+ triangulation.execute_coarsening_and_refinement ();
+ triangulation.refine_global (1);
+
+ for (unsigned int p=1; p<6-dim; ++p)
+ {
+ FE_DGQ<dim> fe(p);
+ DoFHandler<dim> dof_handler(triangulation);
+ dof_handler.distribute_dofs (fe);
+
+ ConstraintMatrix constraints;
+ DoFTools::make_hanging_node_constraints (dof_handler, constraints);
+ constraints.close ();
+
+ Vector<double> interpolant (dof_handler.n_dofs());
+ Vector<float> error (triangulation.n_active_cells());
+ for (unsigned int q=0; q<=p+2; ++q)
+ {
+ // interpolate the function
+ VectorTools::interpolate (dof_handler,
+ F<dim> (q),
+ interpolant);
+ constraints.distribute (interpolant);
+
+ // then compute the interpolation error
+ VectorTools::integrate_difference (dof_handler,
+ interpolant,
+ F<dim> (q),
+ error,
+ QGauss<dim>(q+2),
+ VectorTools::L2_norm);
+ if (q<=p)
+ Assert (error.l2_norm() < 1e-12*interpolant.l2_norm(),
+ ExcInternalError());
+
+ deallog << fe.get_name() << ", P_" << q
+ << ", rel. error=" << error.l2_norm() / interpolant.l2_norm()
+ << std::endl;
+ }
+ }
+}
+
+
+
+int main ()
+{
+ std::ofstream logfile("interpolate_dgq_02/output");
+ logfile.precision (3);
+
+ deallog.attach(logfile);
+ deallog.depth_console(0);
+ deallog.threshold_double(1.e-10);
+
+ test<1>();
+ test<2>();
+ test<3>();
+}
+
--- /dev/null
+
+DEAL::FE_DGQ<1>(1), P_0, rel. error=0
+DEAL::FE_DGQ<1>(1), P_1, rel. error=0
+DEAL::FE_DGQ<1>(1), P_2, rel. error=0.00243
+DEAL::FE_DGQ<1>(1), P_3, rel. error=0.00676
+DEAL::FE_DGQ<1>(2), P_0, rel. error=0
+DEAL::FE_DGQ<1>(2), P_1, rel. error=0
+DEAL::FE_DGQ<1>(2), P_2, rel. error=0
+DEAL::FE_DGQ<1>(2), P_3, rel. error=8.78e-05
+DEAL::FE_DGQ<1>(2), P_4, rel. error=0.000315
+DEAL::FE_DGQ<1>(3), P_0, rel. error=0
+DEAL::FE_DGQ<1>(3), P_1, rel. error=0
+DEAL::FE_DGQ<1>(3), P_2, rel. error=0
+DEAL::FE_DGQ<1>(3), P_3, rel. error=0
+DEAL::FE_DGQ<1>(3), P_4, rel. error=3.99e-06
+DEAL::FE_DGQ<1>(3), P_5, rel. error=1.74e-05
+DEAL::FE_DGQ<1>(4), P_0, rel. error=0
+DEAL::FE_DGQ<1>(4), P_1, rel. error=0
+DEAL::FE_DGQ<1>(4), P_2, rel. error=0
+DEAL::FE_DGQ<1>(4), P_3, rel. error=0
+DEAL::FE_DGQ<1>(4), P_4, rel. error=0
+DEAL::FE_DGQ<1>(4), P_5, rel. error=2.07e-07
+DEAL::FE_DGQ<1>(4), P_6, rel. error=1.06e-06
+DEAL::FE_DGQ<2>(1), P_0, rel. error=0
+DEAL::FE_DGQ<2>(1), P_1, rel. error=0
+DEAL::FE_DGQ<2>(1), P_2, rel. error=0.00100
+DEAL::FE_DGQ<2>(1), P_3, rel. error=0.00249
+DEAL::FE_DGQ<2>(2), P_0, rel. error=0
+DEAL::FE_DGQ<2>(2), P_1, rel. error=0
+DEAL::FE_DGQ<2>(2), P_2, rel. error=0
+DEAL::FE_DGQ<2>(2), P_3, rel. error=2.41e-05
+DEAL::FE_DGQ<2>(2), P_4, rel. error=7.74e-05
+DEAL::FE_DGQ<2>(3), P_0, rel. error=0
+DEAL::FE_DGQ<2>(3), P_1, rel. error=0
+DEAL::FE_DGQ<2>(3), P_2, rel. error=0
+DEAL::FE_DGQ<2>(3), P_3, rel. error=0
+DEAL::FE_DGQ<2>(3), P_4, rel. error=1.07e-06
+DEAL::FE_DGQ<2>(3), P_5, rel. error=4.06e-06
+DEAL::FE_DGQ<3>(1), P_0, rel. error=0
+DEAL::FE_DGQ<3>(1), P_1, rel. error=0
+DEAL::FE_DGQ<3>(1), P_2, rel. error=0.000375
+DEAL::FE_DGQ<3>(1), P_3, rel. error=0.000898
+DEAL::FE_DGQ<3>(2), P_0, rel. error=0
+DEAL::FE_DGQ<3>(2), P_1, rel. error=0
+DEAL::FE_DGQ<3>(2), P_2, rel. error=0
+DEAL::FE_DGQ<3>(2), P_3, rel. error=6.40e-06
+DEAL::FE_DGQ<3>(2), P_4, rel. error=1.98e-05