* is pointing the other direction. There are not very many places in
* application programs where you need this information actually, but
* a few places in the library make use of this. Note that in 2d, the
- * result is always @p true.
+ * result is always @p true. However, while every face in 2d is always
+ * in standard orientation, you can sometimes specify something to
+ * assume that this is not so; an example is the function
+ * DoFTools::make_periodicity_constraints().
*
* There are two other flags that describe the orientation of a face:
* face_flip and face_rotation. Some documentation for these
* @return The index of this degree of freedom within the set
* of degrees of freedom on the entire cell. The returned value
* will be between zero and dofs_per_cell.
- */
+ *
+ * @note This function exists in this class because that is where it
+ * was first implemented. However, it can't really work in the most
+ * general case without knowing what element we have. The reason is that
+ * when a face is flipped or rotated, we also need to know whether we
+ * need to swap the degrees of freedom on this face, or whether they
+ * are immune from this. For this, consider the situation of a $Q_3$
+ * element in 2d. If face_flip is true, then we need to consider
+ * the two degrees of freedom on the edge in reverse order. On the other
+ * hand, if the element were a $Q_1^2$, then because the two degrees of
+ * freedom on this edge belong to different vector components, they
+ * should not be considered in reverse order. What all of this shows is
+ * that the function can't work if there are more than one degree of
+ * freedom per line or quad, and that in these cases the function will
+ * throw an exception pointing out that this functionality will need
+ * to be provided by a derived class that knows what degrees of freedom
+ * actually represent.
+ */
+ virtual
unsigned int face_to_cell_index (const unsigned int face_dof_index,
const unsigned int face,
const bool face_orientation = true,
Assert (face < GeometryInfo<dim>::faces_per_cell,
ExcIndexRange(face, 0, GeometryInfo<dim>::faces_per_cell));
+ // see the function's documentation for an explanation of this
+ // assertion -- in essence, derived classes have to implement
+ // an overloaded version of this function
+ Assert ((this->dofs_per_line <= 1) && (this->dofs_per_quad <= 1),
+ ExcMessage ("The function in this base class can not handle this case. "
+ "Rather, the derived class you are using must provide "
+ "an overloaded version but apparently hasn't done so. See "
+ "the documentation of this function for more information."));
+
// DoF on a vertex
if (face_index < this->first_face_line_index)
{
--- /dev/null
+// ---------------------------------------------------------------------
+// $Id$
+//
+// Copyright (C) 1998 - 2013 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 at
+// the top level of the deal.II distribution.
+//
+// ---------------------------------------------------------------------
+
+
+// it turns out that FE_Q::face_to_cell_index() had a bug for elements beyond
+// Q2 when using the face flip flag. this test is for the 2d case for the Q1
+// case
+
+#include "../tests.h"
+#include <iostream>
+#include <fstream>
+
+#include <deal.II/base/logstream.h>
+#include <deal.II/fe/fe_q.h>
+
+template<int dim>
+void test()
+{
+ FE_Q<dim> fe(1);
+ const unsigned int dofs_per_face = fe.dofs_per_face;
+
+ for (unsigned int face=0; face<4; ++face)
+ {
+ deallog << "Face=" << face << std::endl;
+
+ for (int flip=0; flip<2; ++flip)
+ {
+ deallog << " flip=" << (flip == 0 ? "false" : "true")
+ << std::endl
+ << " ";
+ for (unsigned int i = 0; i < dofs_per_face; ++i)
+ deallog << fe.face_to_cell_index(i, face,
+ true,
+ (flip == 0 ? false : true),
+ false) << " - ";
+ deallog << std::endl;
+ }
+ }
+}
+
+int main()
+{
+ std::ofstream logfile("face_to_cell_q1_2d/output");
+ deallog.attach(logfile);
+ deallog.depth_console(0);
+ deallog.threshold_double(1.e-10);
+
+ test<2>();
+}
+
+
+
--- /dev/null
+
+DEAL::Face=0
+DEAL:: flip=false
+DEAL:: 0 - 2 -
+DEAL:: flip=true
+DEAL:: 2 - 0 -
+DEAL::Face=1
+DEAL:: flip=false
+DEAL:: 1 - 3 -
+DEAL:: flip=true
+DEAL:: 3 - 1 -
+DEAL::Face=2
+DEAL:: flip=false
+DEAL:: 0 - 1 -
+DEAL:: flip=true
+DEAL:: 1 - 0 -
+DEAL::Face=3
+DEAL:: flip=false
+DEAL:: 2 - 3 -
+DEAL:: flip=true
+DEAL:: 3 - 2 -
--- /dev/null
+// ---------------------------------------------------------------------
+// $Id$
+//
+// Copyright (C) 1998 - 2013 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 at
+// the top level of the deal.II distribution.
+//
+// ---------------------------------------------------------------------
+
+
+// it turns out that FE_Q::face_to_cell_index() had a bug for elements beyond
+// Q2 when using the face flip flag. this test is for the 2d case for the Q2
+// case
+
+#include "../tests.h"
+#include <iostream>
+#include <fstream>
+
+#include <deal.II/base/logstream.h>
+#include <deal.II/fe/fe_q.h>
+
+template<int dim>
+void test()
+{
+ FE_Q<dim> fe(2);
+ const unsigned int dofs_per_face = fe.dofs_per_face;
+
+ for (unsigned int face=0; face<4; ++face)
+ {
+ deallog << "Face=" << face << std::endl;
+
+ for (int flip=0; flip<2; ++flip)
+ {
+ deallog << " flip=" << (flip == 0 ? "false" : "true")
+ << std::endl
+ << " ";
+ for (unsigned int i = 0; i < dofs_per_face; ++i)
+ deallog << fe.face_to_cell_index(i, face,
+ true,
+ (flip == 0 ? false : true),
+ false) << " - ";
+ deallog << std::endl;
+ }
+ }
+}
+
+int main()
+{
+ std::ofstream logfile("face_to_cell_q2_2d/output");
+ deallog.attach(logfile);
+ deallog.depth_console(0);
+ deallog.threshold_double(1.e-10);
+
+ test<2>();
+}
+
+
+
--- /dev/null
+
+DEAL::Face=0
+DEAL:: flip=false
+DEAL:: 0 - 2 - 4 -
+DEAL:: flip=true
+DEAL:: 2 - 0 - 4 -
+DEAL::Face=1
+DEAL:: flip=false
+DEAL:: 1 - 3 - 5 -
+DEAL:: flip=true
+DEAL:: 3 - 1 - 5 -
+DEAL::Face=2
+DEAL:: flip=false
+DEAL:: 0 - 1 - 6 -
+DEAL:: flip=true
+DEAL:: 1 - 0 - 6 -
+DEAL::Face=3
+DEAL:: flip=false
+DEAL:: 2 - 3 - 7 -
+DEAL:: flip=true
+DEAL:: 3 - 2 - 7 -
projects / dealii.git / commitdiff