Update. Rename environment variable to DEAL_II_DIFF.

git-svn-id: https://svn.dealii.org/trunk@28920 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/doc/development/testsuite.html b/deal.II/doc/development/testsuite.html
index ff979a586219342e2471f2b966ed9646393682aa..a427b87424b5c7504aac4561c2b076e8f7792ff4 100644 (file)
--- a/deal.II/doc/development/testsuite.html
+++ b/deal.II/doc/development/testsuite.html
@@ -162,12 +162,15 @@
     </p>
 
     <p>
-    Not all tests will succeed on your machine, because you might not have
-    configured with all the required packages (for example PETSc or Trilinos)
-    or, because your machine has slightly different floating point outputs.
-    To improve the number of tests that work correctly, install the tool
-    numdiff and export the environment variable
-    <code>export DEALII_DIFF="numdiff -a 1e-6 -q"</code> 
+    Not all tests succeed on every machine even if all computations are
+    correct, because you might not have configured with all the required
+    packages (for example PETSc or Trilinos), or because your machine
+    generates slightly different floating point outputs.  To increase the
+    number of tests that work correctly, install the
+    <a href="http://www.nongnu.org/numdiff/">numdiff</a> toold that compares
+    stored and newly created output files based on floating point
+    tolerances. To use it, simply export the environment variable
+    <code>export DEAL_II_DIFF="numdiff -a 1e-6 -q"</code>
     before running the testsuite.
     </p>