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https://issues.apache.org/jira/browse/MATH-1498?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16927724#comment-16927724
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Alex D Herbert commented on MATH-1498:
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Thanks for the report.
The distributions in the most recent commons-math4 project have been moved to
the new commons-statistics project. This code is currently unreleased and I
have fixed the bug.
> getNumericalVariance of LogisticDistribution is incorrect
> ---------------------------------------------------------
>
> Key: MATH-1498
> URL: https://issues.apache.org/jira/browse/MATH-1498
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.6.1
> Environment: Windows, Java 8
> Reporter: WFR
> Priority: Minor
> Original Estimate: 2h
> Remaining Estimate: 2h
>
> The variance of a logistic distribution returned by
> LogisticDistribution.getNumericalVariance() is incorrect:
> It is computed by (MathUtils.{color:#9876aa}PI_SQUARED {color}/
> {color:#6897bb}3.0{color}) * ({color:#6897bb}1.0 {color}/ ({color:#9876aa}s
> {color}* {color:#9876aa}s{color})){color:#cc7832};{color}
> {color:#cc7832}it should be {color}(MathUtils.{color:#9876aa}PI_SQUARED
> {color}/ {color:#6897bb}3.0{color}) * ({color:#9876aa}s {color}*
> {color:#9876aa}s{color}){color:#cc7832};{color}
> {color:#cc7832}Compare Wikipedia:
> https://en.wikipedia.org/wiki/Logistic_distribution{color}
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