From 6964e6dbcc9de5b5322f7df40e8049c55ee744e6 Mon Sep 17 00:00:00 2001 From: wolf Date: Sat, 22 Mar 2003 19:36:03 +0000 Subject: [PATCH] Hopefully clarify docs a little. git-svn-id: https://svn.dealii.org/trunk@7338 0785d39b-7218-0410-832d-ea1e28bc413d --- deal.II/deal.II/include/dofs/dof_constraints.h | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/deal.II/deal.II/include/dofs/dof_constraints.h b/deal.II/deal.II/include/dofs/dof_constraints.h index 7d6462a0ec..533792574f 100644 --- a/deal.II/deal.II/include/dofs/dof_constraints.h +++ b/deal.II/deal.II/include/dofs/dof_constraints.h @@ -30,12 +30,21 @@ class BlockIndices; /** - * This class represents the matrix denoting the distribution of the degrees - * of freedom of hanging nodes. + * This class implements linear homogeneous constraints on degrees of + * freedom. In particular, it handles constraints of the form + * $x_{i1} = \sum_{j=2}^M a_{i_j} x_{i_j}$. Each "line" in objects of this + * class corresponds to one such constraint, with the number of the + * line being $i1$, and the entries in this line being pairs + * $(i_j,a_{i_j})$. Note that the constraints are linear in the $x_i$, + * and that there is not constant (non-homogeneous) term in the + * constraint. However, this is exactly the form we need for hanging + * node and certain other constraints, where we need to constrain one + * degree of freedom in terms of others. The name of the class stems + * from the fact that these constraints can be represented in matrix + * form as $X x = 0$, and this object then describes the matrix $X$. * * The matrix is organized in lines (rows), but only those lines are stored - * where constraints are present. Lines where only one entry (identity) is - * present are not stored if not explicitly inserted. + * where constraints are present. * * Constraint matrices are used to handle hanging nodes and other constrained * degrees of freedom. When building the global system matrix and the right -- 2.39.5