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https://issues.apache.org/jira/browse/MATH-718?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13170599#comment-13170599
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Christian Winter commented on MATH-718:
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There seem to be stability problems with Beta.regularizedBeta(...) when using 
extreme parameters. 
{{PascalDistribution.cumulativeProbability(Integer.MAX_VALUE)}} returns {{NaN}} 
instead of 1. We should look for a way to avoid both infinite values and NaNs 
in the implementation of the regularized beta function.
                
> 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
>
> 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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