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From "Paolo Repele (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MATH-578) Decrease DescriptiveStatistics performance from 2.0 to 2.2
Date Mon, 16 May 2011 15:47:47 GMT

     [ https://issues.apache.org/jira/browse/MATH-578?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Paolo Repele updated MATH-578:
------------------------------

    Attachment: percentile.png

Image file to show the profile snapshot

> Decrease DescriptiveStatistics performance from 2.0 to 2.2
> ----------------------------------------------------------
>
>                 Key: MATH-578
>                 URL: https://issues.apache.org/jira/browse/MATH-578
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 2.2
>         Environment: Linux
>            Reporter: Paolo Repele
>            Assignee: Mikkel Meyer Andersen
>            Priority: Minor
>         Attachments: percentile.png
>
>
> Switching between commons-math 2.0 to 2.2 we note how the
> DescriptiveStatistics.addValue(double) has decrease the performance.
> I tested with 2 million values.
> DescriptiveStatistics ds = new DescriptiveStatistics();
> for(int i = 0; i<1000*1000*2; i++) { //2 million values
>     ds.addValue(v);
> }
> ds.getPercentile(50);
> Seems that depending by the values inserted in the DescriptiveStatistics it takes different
time:
> * with a single value (0)
> ** 2.0 -> take ~500 ms
> ** 2.2 -> take more than 10 minutes
> * with 50% fixed value (0) and 50% Math.random()
> ** 2.0 -> take ~500 ms
> ** 2.2 -> take ~250000 ms -> ~250 second
> * with 100% Math.random()
> ** 2.0 -> take ~500 ms
> ** 2.2 -> take ~70 ms

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