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Posted to issues@commons.apache.org by "Mikkel Meyer Andersen (JIRA)" <ji...@apache.org> on 2012/06/12 11:19:42 UTC
[jira] [Reopened] (MATH-790) Mann-Whitney U Test Suffers From
Integer Overflow With Large Data Sets
[ https://issues.apache.org/jira/browse/MATH-790?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Mikkel Meyer Andersen reopened MATH-790:
----------------------------------------
Thomas Neidhart suspect an overflow issues is still present.
> Mann-Whitney U Test Suffers From Integer Overflow With Large Data Sets
> ----------------------------------------------------------------------
>
> Key: MATH-790
> URL: https://issues.apache.org/jira/browse/MATH-790
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.0, Nightly Builds
> Environment: Ubuntu Linux x64, Sun Java 6
> Reporter: James Pickering
> Assignee: Mikkel Meyer Andersen
> Priority: Minor
> Labels: newbie, patch
> Fix For: 3.1
>
> Attachments: MannWhitnetUOVerflowPatch.diff
>
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> When performing a Mann-Whitney U Test on large data sets (the attached test uses two 1500 element sets), intermediate integer values used in calculateAsymptoticPValue can overflow, leading to invalid results, such as p-values of NaN, or incorrect calculations.
> Attached is a patch, including a test, and a fix, which modifies the affected code to use doubles
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