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Posted to issues@commons.apache.org by "Sebb (JIRA)" <ji...@apache.org> on 2013/03/20 11:55:16 UTC
[jira] [Commented] (MATH-951) Patch: Faster implementation of
double org.apache.commons.math3.FastMath.copySign(double, double)
[ https://issues.apache.org/jira/browse/MATH-951?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13607500#comment-13607500 ]
Sebb commented on MATH-951:
---------------------------
Surely m^s can overflow an int here? What happens then?
Also, I suspect exponentiation speed may vary considerably between processors - what CPU are you using?
> Patch: Faster implementation of double org.apache.commons.math3.FastMath.copySign(double, double)
> -------------------------------------------------------------------------------------------------
>
> Key: MATH-951
> URL: https://issues.apache.org/jira/browse/MATH-951
> Project: Commons Math
> Issue Type: Improvement
> Affects Versions: 3.2
> Environment: java version "1.6.0_27"
> OpenJDK Runtime Environment (IcedTea6 1.12.3) (6b27-1.12.3-1)
> OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode)
> Linux debian 3.2.0-4-amd64 #2 SMP Wed Jan 2 01:41:29 PST 2013 x86_64 GNU/Linux
> Intel(R) Core(TM) i5-2500 CPU @ 3.30GHz
> Reporter: Charles Cooper
> Priority: Minor
> Labels: patch, performance
> Fix For: 3.2
>
> Attachments: patch
>
> Original Estimate: 0h
> Remaining Estimate: 0h
>
> Between 40-50% faster than both current implementation and java.lang.Math.copySign by my (sloppy) benchmark. Patch attached.
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