[jira] Commented: (MATH-282) ChiSquaredDistributionImpl.cumulativeProbability > 1

["Phil Steitz (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MATH-282?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12764514#action_12764514 ] 

Phil Steitz commented on MATH-282:
----------------------------------

The problem in Gamma.regularizedGammaP reported here is also causing incorrect results from PoissonDistributionImpl#cumulativeProbability.  The (currently disabled) test case, testCumulativeProbabilitySpecial() in PoissonDistributionTest illustrates the problem.  For some (not all) large lambda and some (not all) x in (0.9 * lambda, lambda), NaN or zero cumulative probabilities are returned.

> ChiSquaredDistributionImpl.cumulativeProbability > 1
> ----------------------------------------------------
>
>                 Key: MATH-282
>                 URL: https://issues.apache.org/jira/browse/MATH-282
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 1.0, 1.1, 1.2, 2.0
>         Environment: called from Scala code
>            Reporter: Adam Kiezun
>             Fix For: 2.1
>
>         Attachments: math-282.patch
>
>
> Calling 
> new ChiSquaredDistributionImpl(1.0).cumulativeProbability(66.41528551683048)
> returns 1.000000000000004, which is bogus (should never be > 1)

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