Advertize correct exception.


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Typo.


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1605776 13f79535-47bb-0310-9956-ffa450edef68
MATH-1130
Shortcut (in case one of the arguments is NaN). Thanks to Venkatesha Murthy.


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1605777 13f79535-47bb-0310-9956-ffa450edef68