// $Id$
// Version: $Name$
//
-// Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 by the deal.II authors
+// Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 by the deal.II authors
//
// This file is subject to QPL and may not be distributed
// without copyright and license information. Please refer
*
* @image html hp-refinement-simple.png
*
- * there are three constraints: first $x_2=\frac 12 x_0 + \frac 12 x_1$, then
- * $x_4=\frac 14 x_0 + \frac 34 x_1$, and finally the identity $x_3=x_1$. All
- * three constraints fit the form given above. Similar constraints occur as
- * hanging nodes even if all used finite elements are identical. While they
- * are most frequent for hanging nodes, constraints of the given form appear
- * also in other contexts, see for example the application the @ref step_11
- * "step-11" tutorial program.
+ * there are three constraints: first $x_2=\frac 12 x_0 + \frac 12
+ * x_1$, then $x_4=\frac 14 x_0 + \frac 34 x_1$, and finally the
+ * identity $x_3=x_1$. All three constraints fit the form given
+ * above. Similar constraints occur as hanging nodes even if all used
+ * finite elements are identical. While they are most frequent for
+ * hanging nodes, constraints of the given form appear also in other
+ * contexts, see for example the application the @ref step_11
+ * "step-11" tutorial program. A special case also covered by the
+ * current class is the constraint $x_i=0$ although this constraint on
+ * linear systems is better and more efficiently handled by the
+ * MatrixTools::apply_boundary_values function.
*
* The algorithms used in the implementation of this class are described in
* some detail in the @ref hp_paper "hp paper".