From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Tue, 18 May 2004 23:23:19 +0000 (+0000)
Subject: Add important comment.
X-Git-Tag: v8.0.0~15167
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5e559fe8f9b6a4272f10dbb892efd88c1b9755d6;p=dealii.git

Add important comment.


git-svn-id: https://svn.dealii.org/trunk@9262 0785d39b-7218-0410-832d-ea1e28bc413d
---

diff --git a/deal.II/deal.II/include/dofs/dof_handler.h b/deal.II/deal.II/include/dofs/dof_handler.h
index 44ae5b907d..6a87bc382f 100644
--- a/deal.II/deal.II/include/dofs/dof_handler.h
+++ b/deal.II/deal.II/include/dofs/dof_handler.h
@@ -372,6 +372,32 @@ class DoFHandler  :  public Subscriptor,
 				      * picture drawing. An example can be
 				      * found in the implementation of this
 				      * function.
+				      *
+				      * Note that this function is
+				      * most often used to determine
+				      * the maximal row length for
+				      * sparsity
+				      * patterns. Unfortunately, the
+				      * while the estimates returned
+				      * by this function are rather
+				      * accurate in 1d and 2d, they
+				      * are often significantly too
+				      * high in 3d, leading the
+				      * SparsityPattern class to
+				      * allocate much too much memory
+				      * in some cases. Unless someone
+				      * comes around to improving the
+				      * present function for 3d, there
+				      * is not very much one can do
+				      * about these cases. The typical
+				      * way to work around this
+				      * problem is to use an
+				      * intermediate compressed
+				      * sparsity pattern that only
+				      * allocated memory on
+				      * demand. Refer to the step-11
+				      * example program on how to do
+				      * this.
 				      */
     unsigned int max_couplings_between_dofs () const;