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From Thomas Neidhart <thomas.neidh...@gmail.com>
Subject Re: svn commit: r1348024 - in /commons/proper/math/trunk/src: main/java/org/apache/commons/math3/stat/inference/MannWhitneyUTest.java test/java/org/apache/commons/math3/stat/inference/MannWhitneyUTestTest.java
Date Mon, 11 Jun 2012 23:25:40 GMT
On 06/08/2012 01:04 PM, mikl@apache.org wrote:
> Author: mikl
> Date: Fri Jun  8 11:04:11 2012
> New Revision: 1348024
> 
> URL: http://svn.apache.org/viewvc?rev=1348024&view=rev
> Log:
> MATH-790: Patch applied to fix the overflow issue.
> 
> Modified:
>     commons/proper/math/trunk/src/main/java/org/apache/commons/math3/stat/inference/MannWhitneyUTest.java
>     commons/proper/math/trunk/src/test/java/org/apache/commons/math3/stat/inference/MannWhitneyUTestTest.java
> 
> Modified: commons/proper/math/trunk/src/main/java/org/apache/commons/math3/stat/inference/MannWhitneyUTest.java
> URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math3/stat/inference/MannWhitneyUTest.java?rev=1348024&r1=1348023&r2=1348024&view=diff
> ==============================================================================
> --- commons/proper/math/trunk/src/main/java/org/apache/commons/math3/stat/inference/MannWhitneyUTest.java
(original)
> +++ commons/proper/math/trunk/src/main/java/org/apache/commons/math3/stat/inference/MannWhitneyUTest.java
Fri Jun  8 11:04:11 2012
> @@ -170,11 +170,11 @@ public class MannWhitneyUTest {
>                                               final int n2)
>          throws ConvergenceException, MaxCountExceededException {
>  
> -        final int n1n2prod = n1 * n2;
> +        final double n1n2prod = n1 * n2;
>  
>          // http://en.wikipedia.org/wiki/Mann%E2%80%93Whitney_U#Normal_approximation
> -        final double EU = (double) n1n2prod / 2.0;
> -        final double VarU = (double) (n1n2prod * (n1 + n2 + 1)) / 12.0;
> +        final double EU = n1n2prod / 2.0;
> +        final double VarU = n1n2prod * (n1 + n2 + 1) / 12.0;
>  
>          final double z = (Umin - EU) / FastMath.sqrt(VarU);

just a small thing, but wouldn't it be better to do a long
multiplication and convert the result to double?

Thomas

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