From: bangerth Date: Sat, 15 Aug 2009 01:45:20 +0000 (+0000) Subject: Fix math error. X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=faabd8be414aa49c4da0ab79cc572fccc16f912a;p=dealii-svn.git Fix math error. git-svn-id: https://svn.dealii.org/trunk@19271 0785d39b-7218-0410-832d-ea1e28bc413d --- diff --git a/deal.II/doc/doxygen/headers/multithreading.h b/deal.II/doc/doxygen/headers/multithreading.h index 97a11df06d..58a4e10f4d 100644 --- a/deal.II/doc/doxygen/headers/multithreading.h +++ b/deal.II/doc/doxygen/headers/multithreading.h @@ -773,7 +773,8 @@ * point where we want to copy the local into the global contributions the * order is still as if we computed things sequentially. In other words, it * may happen that we add the contributions of cell 1 before those of cell - * 0. That may seem harmless because addition is commutative, but in fact it + * 0. That may seem harmless because addition is commutative and + * associative, but in fact it * is not if done in floating point arithmetic: $a+b+c \neq a+c+b$ -- take * for example $a=1, b=-1, c=10^{-20}$ (because $1+10^{-20}=1$ in floating * point arithmetic, using double precision).