Merge pull request numpy#4697 from charris/update-1.9.0-notes

DOC: Update 1.9.0-notes to mention pairwise summation.
wackywendell · Jul 7, 2014 · 594b0de · 594b0de
2 parents d244ec7 + cdfbc69
commit 594b0de
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/doc/release/1.9.0-notes.rst b/doc/release/1.9.0-notes.rst
@@ -331,6 +331,12 @@ in either an error being raised, or wrong results computed.
 Improvements
 ============
 
+Better numerical stability for sum in some cases
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Pairwise summation is now used in the sum method, but only along the fast
+axis and for groups of the values <= 8192 in length. This should also
+improve the accuracy of var and std in some common cases.
+
 Percentile implemented in terms of ``np.partition``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ``np.percentile`` has been implemented in terms of ``np.partition`` which