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https://issues.apache.org/jira/browse/MATH-1153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14249095#comment-14249095
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Thomas Neidhart commented on MATH-1153:
---------------------------------------

The same failures appear when using the original patch, so there was no error 
during the integration / renaming of variables.

It looks like the test failure 
(RandomDataGeneratorTest.testNextInversionDeviate) is due to changes how the 
random generator is used during sampling. Thus the assumptions made in the test 
are not correct anymore. 

> Sampling from a 'BetaDistribution' is slow
> ------------------------------------------
>
>                 Key: MATH-1153
>                 URL: https://issues.apache.org/jira/browse/MATH-1153
>             Project: Commons Math
>          Issue Type: Improvement
>            Reporter: Sergei Lebedev
>            Priority: Minor
>             Fix For: 3.4
>
>         Attachments: ChengBetaSampler.java, ChengBetaSamplerTest.java
>
>
> Currently the `BetaDistribution#sample` uses inverse CDF method, which is 
> quite slow for sampling-intensive computations. I've implemented a method 
> from the R. C. H. Cheng paper and it seems to work much better. Here's a 
> simple microbenchmark:
> {code}
> o.j.b.s.SamplingBenchmark.algorithmBCorBB       1e-3    1000  thrpt        5  
> 2592200.015    14391.520  ops/s
> o.j.b.s.SamplingBenchmark.algorithmBCorBB       1000    1000  thrpt        5  
> 3210800.292    33330.791  ops/s
> o.j.b.s.SamplingBenchmark.commonsVersion        1e-3    1000  thrpt        5  
>   31034.225      438.273  ops/s
> o.j.b.s.SamplingBenchmark.commonsVersion        1000    1000  thrpt        5  
>   21834.010      433.324  ops/s
> {code}
> Should I submit a patch?
> R. C. H. Cheng (1978). Generating beta variates with nonintegral shape 
> parameters. Communications of the ACM, 21, 317–322.



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