MATH-1067
Avoid infinite recursion. Thanks to Florian Erhard.


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1546350 13f79535-47bb-0310-9956-ffa450edef68
[MATH-1068] Avoid overflow in Kendalls correlation for large input arrays.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1546840 13f79535-47bb-0310-9956-ffa450edef68
Fetch upstream