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https://issues.apache.org/jira/browse/MATH-385?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Phil Steitz reopened MATH-385:
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In [math] we usually wait to close issues until the fix version is released.
Reopening so I can just set the status to RESOLVED.

> Characteristic (support, mean, variance, ...) on Distributions
> --------------------------------------------------------------
>
>                 Key: MATH-385
>                 URL: https://issues.apache.org/jira/browse/MATH-385
>             Project: Commons Math
>          Issue Type: New Feature
>            Reporter: Mikkel Meyer Andersen
>            Assignee: Mikkel Meyer Andersen
>             Fix For: 2.2
>
>         Attachments: MATH385-PATCH1, MATH385-PATCH2, MATH385-PATCH3
>
>   Original Estimate: 5h
>  Remaining Estimate: 5h
>
> I wish that the Distributions could contain some characteristics. For example 
> support, mean, and variance.
> Support:
> AbstractContinuousDistribution and AbstractIntegerDistribution should have 
> double getSupport{Lower, Upper}Bound() and int getSupport{Lower, 
> Upper}Bound(), respectively. Also methods a la boolean isSupport{Lower, 
> Upper}BoundInclusive() on AbstractContinuousDistribution should reflect if 
> the support is open of closed. In practise the implemented distributions are 
> easy since the support for all continuous distributions are real intervals 
> (connected sets), and the support for all the discrete distributions are 
> connected integer sets. This means that the lower and upper bound (together 
> with isSupport{Lower, Upper}BoundInclusive() on 
> AbstractContinuousDistribution because it is not needed on the discrete 
> distributions because of their nature) are sufficient for determine the 
> support.
> Mean and variance:
> double get{Mean, Variance}() should be on AbstractDistribution.
> With such characteristic an invalidateParameters-method might come in handy 
> because they often depend on the parameters. The characteristics should not 
> be calculated before the first time they are get'ted, and when calculated, 
> they should be saved for later use.  When parameters change, an 
> invalidateParameters-method should be called to force the characteristics to 
> be recalculated.
> Values such as Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY, and 
> Double.NaN should be used where appropriate.

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