From a9e53cc16ef0d2ccf32257293bd572cc187d6246 Mon Sep 17 00:00:00 2001 From: Wolfgang Bangerth Date: Tue, 10 May 2011 15:57:01 +0000 Subject: [PATCH] Add something to the documentation. git-svn-id: https://svn.dealii.org/trunk@23686 0785d39b-7218-0410-832d-ea1e28bc413d --- .../deal.II/lac/trilinos_sparse_matrix.h | 25 ++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/deal.II/include/deal.II/lac/trilinos_sparse_matrix.h b/deal.II/include/deal.II/lac/trilinos_sparse_matrix.h index 7da9982b4a..16fd4d50f4 100644 --- a/deal.II/include/deal.II/lac/trilinos_sparse_matrix.h +++ b/deal.II/include/deal.II/lac/trilinos_sparse_matrix.h @@ -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; -- 2.39.5