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From "Luc Maisonobe (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MATH-650) FastMath has static code which slows the first access to FastMath
Date Thu, 09 Feb 2012 16:33:59 GMT

    [ https://issues.apache.org/jira/browse/MATH-650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13204625#comment-13204625
] 

Luc Maisonobe commented on MATH-650:
------------------------------------

On the Android platform I get this for the total time (i.e using the "time" unix command to
launch the dalvik virtual machine):

* literal arrays: between 0.09 and 0.12 s
* resources: between 0.13 and 0.15 s
* recompute: almost constant 0.25 s
                
> FastMath has static code which slows the first access to FastMath
> -----------------------------------------------------------------
>
>                 Key: MATH-650
>                 URL: https://issues.apache.org/jira/browse/MATH-650
>             Project: Commons Math
>          Issue Type: Improvement
>    Affects Versions: Nightly Builds
>         Environment: Android 2.3 (Dalvik VM with JIT)
>            Reporter: Alexis Robert
>            Priority: Minor
>             Fix For: 3.0
>
>         Attachments: FastMathLoadCheck.java, LucTestPerformance.java
>
>
> Working on an Android application using Orekit, I've discovered that a simple FastMath.floor()
takes about 4 to 5 secs on a 1GHz Nexus One phone (only the first time it's called). I've
launched the Android profiling tool (traceview) and the problem seems to be linked with the
static portion of FastMath code named "// Initialize tables"
> The timing resulted in :
> - FastMath.slowexp (40.8%)
> - FastMath.expint (39.2%)
>  \- FastMath.quadmult() (95.6% of expint)
> - FastMath.slowlog (18.2%)
> Hoping that would help
> Thanks!
> Alexis Robert

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