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From "Gilles (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MATH-650) FastMath has static code which slows the first access to FastMath
Date Thu, 15 Sep 2011 12:34:08 GMT

     [ https://issues.apache.org/jira/browse/MATH-650?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Gilles updated MATH-650:
------------------------

    Attachment: LucTestPerformance.java

Hi Luc.

Here is a "unit test" that reports timings 
for the set of function calls which you referred to on the ML.
Before those calls, I've added a single call to "abs" (as a trivial function that does not
trigger the tables initialization) in order to estimate the time taken by the "bare" initialization
of "FastMath".


> 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
>         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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