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From "Thomas Neidhart (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MATH-1154) Statistical tests in stat.inference package are very slow due to implicit RandomGenerator initialization
Date Tue, 07 Oct 2014 15:19:34 GMT

    [ https://issues.apache.org/jira/browse/MATH-1154?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14161993#comment-14161993
] 

Thomas Neidhart commented on MATH-1154:
---------------------------------------

Well, I know it is pointless to discuss anything with you as you will never acknowledge anything
else than your POV.

{quote}
I'm proposing to tidy up things and process them in order, and you keep ignoring the suggestion.
If you and the OP want to resolve this issue, then there is only one alternative at present:
Your fix. Please apply it and let's move on to the other suggestions.
{quote}

but I can not leave this statement as is, how do I ignore anything or do not process things
in a reasonable way?

I did the following:

 * attach a clean patch so solve the original issue at hand that does not require additional
changes (open for discussion, I did not apply it)
 * create a separate issue to address the potential performance improvements for existing
rngs
 * re-open the original issue that was referred to by the OP and suggested to discuss the
potential solutions (as currently attached to this issue) on the ml

I mean, seriously, I am fed up with discussions like this.

> Statistical tests in stat.inference package are very slow due to implicit RandomGenerator
initialization
> --------------------------------------------------------------------------------------------------------
>
>                 Key: MATH-1154
>                 URL: https://issues.apache.org/jira/browse/MATH-1154
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 3.3
>            Reporter: Otmar Ertl
>         Attachments: MATH-1154.patch, math3.patch
>
>
> Some statistical tests defined in the stat.inference package (e.g. BinomialTest or ChiSquareTest)
are unnecessarily very slow (up to a factor 20 slower than necessary). The reason is the implicit
slow initialization of a default (Well19937c) random generator instance each time a test is
performed. The affected tests create some distribution instance in order to use some methods
defined therein. However, they do not use any method for random generation. Nevertheless a
random number generator instance is automatically created when creating a distribution instance,
which is the reason for the serious slowdown. The problem is related to MATH-1124.
> There are following solutions:
> 1) Fix the affected statistical tests by passing a light-weight RandomGenerator implementation
(or even null) to the constructor of the distribution.
> 2) Or use for all distributions a RandomGenerator implementation that uses lazy initialization
to generate the Well19937c instance as late as possible. This would also solve MATH-1124.
> I will attach a patch proposal together with a performance test, that will demonstrate
the speed up after a fix.



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