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https://issues.apache.org/jira/browse/MATH-650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13123349#comment-13123349
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Gilles commented on MATH-650:
-----------------------------
{{FastMathLoadCheck}} (revision 1180294):
{noformat}
Using exp(100); how=compute
times result
42677576 2.688117e+43
5338 2.688117e+43
1831 2.688117e+43
1759 2.688117e+43
Using exp(100); how=resources
times result
12930977 2.688117e+43
4650 2.688117e+43
2322 2.688117e+43
2496 2.688117e+43
Using exp(100); how=array
times result
12281292 2.688117e+43
4824 2.688117e+43
1807 2.688117e+43
1877 2.688117e+43
Using max(0,0); how=compute
times result
3293 0.000000e+00
1110 0.000000e+00
375 0.000000e+00
376 0.000000e+00
Using max(0,0); how=resources
times result
2680 0.000000e+00
713 0.000000e+00
382 0.000000e+00
367 0.000000e+00
Using max(0,0); how=array
times result
3065 0.000000e+00
520 0.000000e+00
370 0.000000e+00
376 0.000000e+00
{noformat}
> 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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