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https://issues.apache.org/jira/browse/MATH-585?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13051702#comment-13051702
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Mikkel Meyer Andersen commented on MATH-585:
--------------------------------------------

Now I understand. Originally GammaRejectionSampler was not an inner class but 
its own, and after I made it inner I did not give it as much thought as I 
should have. Thanks for clarifying. I like the solution of removing the 
reference to the outer class in the constructor best.

I'm working on the constants - it's not as easy as I thought, but the hunt is 
kind of fun :-).

> Very slow generation of gamma random variates
> ---------------------------------------------
>
>                 Key: MATH-585
>                 URL: https://issues.apache.org/jira/browse/MATH-585
>             Project: Commons Math
>          Issue Type: Improvement
>    Affects Versions: 2.2, 3.0
>         Environment: All
>            Reporter: Darren Wilkinson
>            Assignee: Mikkel Meyer Andersen
>              Labels: Gamma, Random
>         Attachments: MATH585-1.patch, MATH585-4-gamma.patch
>
>   Original Estimate: 6h
>  Remaining Estimate: 6h
>
> The current implementation of gamma random variate generation works, but uses 
> an inversion method. This is well-known to be a bad idea. Usually a carefully 
> constructed rejection procedure is used. To give an idea of the magnitude of 
> the problem, the Gamma variate generation in Parallel COLT is roughly 50 
> times faster than in Commons Math. 

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