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https://issues.apache.org/jira/browse/MATH-650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13102345#comment-13102345
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Gilles commented on MATH-650:
-----------------------------
Thanks!
What the above shows is that preset tables are a significant improvement over
the code as it was before you raised this issue. However, Sebb came with the
(undisputed) idea of IOD _after_ implementing the (disputed) idea of preset
tables. Thus, using the second JAR, you again get a significant improvement,
thanks to IOD.
What would definitely settle this discussion is to test the current code, once
with {{FastMath.USE_PRECOMPUTED_TABLES}} set to true and once set to false.
Both will use IOD, and the difference will be solely due to using preset tables
versus computing them at runtime.
> 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
>
>
> 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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