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Posted to issues@commons.apache.org by "Luc Maisonobe (JIRA)" <ji...@apache.org> on 2011/03/23 21:23:06 UTC

[jira] [Closed] (MATH-417) improve performance of Percentile

     [ https://issues.apache.org/jira/browse/MATH-417?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Luc Maisonobe closed MATH-417.
------------------------------


Closing issue as it was included in version 2.2, which has been released

> improve performance of Percentile
> ---------------------------------
>
>                 Key: MATH-417
>                 URL: https://issues.apache.org/jira/browse/MATH-417
>             Project: Commons Math
>          Issue Type: Improvement
>    Affects Versions: 2.1
>            Reporter: Luc Maisonobe
>             Fix For: 2.2
>
>
> The 2.1 implementation of Percentile sorts the sample array each time its evaluate method is called.
> When a lot of different percentiles are to be computed for the same sample, this unduces a lot of sorting work that could be avoided.
> When only one percentile is desired, a complete sort is also a waste of efforts as it runs in O(n ln(n)) when only a selection in O(n) would be sufficient.

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