]> https://gitweb.dealii.org/ - dealii.git/commitdiff
Add something to the documentation.
authorWolfgang Bangerth <bangerth@math.tamu.edu>
Tue, 10 May 2011 15:57:01 +0000 (15:57 +0000)
committerWolfgang Bangerth <bangerth@math.tamu.edu>
Tue, 10 May 2011 15:57:01 +0000 (15:57 +0000)
git-svn-id: https://svn.dealii.org/trunk@23686 0785d39b-7218-0410-832d-ea1e28bc413d

deal.II/include/deal.II/lac/trilinos_sparse_matrix.h

index 7da9982b4a5ad34d64a8475de6730e6eb4b7c0bb..16fd4d50f44a2077d43bd58403085f641623ca1e 100644 (file)
@@ -2,7 +2,7 @@
 //    $Id$
 //    Version: $Name$
 //
-//    Copyright (C) 2008, 2009, 2010 by the deal.II authors
+//    Copyright (C) 2008, 2009, 2010, 2011 by the deal.II authors
 //
 //    This file is subject to QPL and may not be  distributed
 //    without copyright and license information. Please refer
@@ -1586,6 +1586,29 @@ namespace TrilinosWrappers
                                         * slow compared to an optimal
                                         * solution, since the sparsity
                                         * of the matrix is not used.
+                                        * On the other hand, if you
+                                        * want to be sure the entry
+                                        * exists, you should use
+                                        * operator() instead.
+                                       *
+                                       * The lack of error checking
+                                       * in this function can also
+                                       * yield surprising results if
+                                       * you have a parallel
+                                       * matrix. In that case, just
+                                       * because you get a zero
+                                       * result from this function
+                                       * does not mean that either
+                                       * the entry does not exist in
+                                       * the sparsity pattern or that
+                                       * it does but has a value of
+                                       * zero. Rather, it could also
+                                       * be that it simply isn't
+                                       * stored on the current
+                                       * processor; in that case, it
+                                       * may be stored on a different
+                                       * processor, and possibly so
+                                       * with a nonzero value.
                                         */
       TrilinosScalar el (const unsigned int i,
                         const unsigned int j) const;

In the beginning the Universe was created. This has made a lot of people very angry and has been widely regarded as a bad move.

Douglas Adams


Typeset in Trocchi and Trocchi Bold Sans Serif.