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From "William Rossi (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MATH-375) Elementary functions in JDK are slower than necessary and not as accurate as they could be.
Date Wed, 09 Jun 2010 14:35:15 GMT

    [ https://issues.apache.org/jira/browse/MATH-375?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12877088#action_12877088
] 

William Rossi commented on MATH-375:
------------------------------------


It hasn't yet been published, I was hoping to get it incorportated into 
larger project such as Commons Math.  With that in mind, I'm willing to 
issue an Apache License for it.

I'm not very familiar with all the procedures of licensing yet, it was 
suggested to me that I post it here and submit a license grant to the 
Apache Foundation separtely.   If that doesn't meet you needs, let me know 
what needs to be done.




> Elementary functions in JDK are slower than necessary and not as accurate as they could
be.
> -------------------------------------------------------------------------------------------
>
>                 Key: MATH-375
>                 URL: https://issues.apache.org/jira/browse/MATH-375
>             Project: Commons Math
>          Issue Type: New Feature
>         Environment: JDK 1.4 - 1.6
>            Reporter: William Rossi
>         Attachments: FastMath.tar.gz
>
>
> I would like to contribute improved versions on exp(), log(), pow(), etc.  to the project.
 Please refer to this discussion thread http://markmail.org/message/zyeoguw6gwtofm62.
> I have developed over the past year a set of elementary functions similar to those in
java.lang.Math, but with the following characteristics:
> * Higher performance.
> * Better accuracy.  Results are accurate to slightly more that +/- 0.5 ULP.
> * Pure Java.  The standard Math class is impleneted via JNI, and thus takes a performance
hit.
> Note that some functions such as exp are nearly twice as fast in my implementation.  
I've seen it 3 times faster on different processors.   The preformance varies by the relative
speed of calculation vs memory lookups.
> The functions are implemented as tables of values in extra precision (approx 70 bits),
and then interpolated with a minimax polynomial.

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