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From Sébastien Brisard (Resolved) (JIRA) <j...@apache.org>
Subject [jira] [Resolved] (MATH-718) inverseCumulativeProbability of BinomialDistribution returns wrong value for large trials.
Date Sat, 04 Feb 2012 06:33:54 GMT

     [ https://issues.apache.org/jira/browse/MATH-718?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sébastien Brisard resolved MATH-718.
------------------------------------

       Resolution: Later
    Fix Version/s: 4.0
                   3.1
         Assignee:     (was: Sébastien Brisard)

As rightly pointed out by Christian, this issue is strongly related to MATH-738.
                
> inverseCumulativeProbability of BinomialDistribution returns wrong value for large trials.
> ------------------------------------------------------------------------------------------
>
>                 Key: MATH-718
>                 URL: https://issues.apache.org/jira/browse/MATH-718
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 2.2, 3.0
>            Reporter: Yuji Uchiyama
>             Fix For: 3.1, 4.0
>
>
> The inverseCumulativeProbability method of the BinomialDistributionImpl class returns
wrong value for large trials.  Following code will be reproduce the problem.
> {{System.out.println(new BinomialDistributionImpl(1000000, 0.5).inverseCumulativeProbability(0.5));}}
> This returns 499525, though it should be 499999.
> I'm not sure how it should be fixed, but the cause is that the cumulativeProbability
method returns Infinity, not NaN.  As the result the checkedCumulativeProbability method doesn't
work as expected.

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