]> https://gitweb.dealii.org/ - dealii.git/commitdiff
Add provisional version, to be finished at home later today.
authorWolfgang Bangerth <bangerth@math.tamu.edu>
Thu, 16 Sep 2010 21:12:19 +0000 (21:12 +0000)
committerWolfgang Bangerth <bangerth@math.tamu.edu>
Thu, 16 Sep 2010 21:12:19 +0000 (21:12 +0000)
git-svn-id: https://svn.dealii.org/trunk@22003 0785d39b-7218-0410-832d-ea1e28bc413d

deal.II/doc/doxygen/headers/constraints.h [new file with mode: 0644]

diff --git a/deal.II/doc/doxygen/headers/constraints.h b/deal.II/doc/doxygen/headers/constraints.h
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+//-------------------------------------------------------------------------
+//    $Id$
+//    Version: $Name$
+//
+//    Copyright (C) 2010 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.
+//
+//-------------------------------------------------------------------------
+
+/**
+ * @defgroup constraints Constraints on degrees of freedom
+ * @ingroup dofs
+ *
+ * This module deals with constraints on degrees of
+ * freedom. Constraints typically come from several sources, for
+ * example:
+ * - If you have Dirichlet-type boundary conditions, one usually enforces
+ *   them by requiring that that degrees of freedom on the boundary have
+ *   particular values, for example $x_12=42$ if the boundary condition
+ *   requires that the finite element solution at the location of degree
+ *   of freedom 12 has the value 42.
+ *
+ * This class implements dealing with linear (possibly inhomogeneous)
+ * constraints on degrees of freedom. In particular, it handles constraints of
+ * the form $x_{i_1} = \sum_{j=2}^M a_{i_j} x_{i_j} + b_i$. In the context of
+ * adaptive finite elements, such constraints appear most frequently as
+ * "hanging nodes" and for implementing Dirichlet boundary conditions in
+ * strong form. The class is meant to deal with a limited number of
+ * constraints relative to the total number of degrees of freedom, for example
+ * a few per cent up to maybe 30 per cent; and with a linear combination of
+ * $M$ other degrees of freedom where $M$ is also relatively small (no larger
+ * than at most around the average number of entries per row of a linear
+ * system). It is <em>not</em> meant to describe full rank linear systems.
+ */

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