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https://issues.apache.org/jira/browse/MATH-650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13100743#comment-13100743
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Gilles commented on MATH-650:
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I just want to understand where time is lost. As I said already, I understand
that IOD is really useful.
Sebb reports that loading precomputed tables is twice faster, but that is
without IOD, if I understood correctly. I was interested in how much more is
gained with preset arrays in the real use-case.
If we refer to the description of this issue, the problem is that
"FastMath.floor" takes about 5 seconds for the first call. Now, with IOD, what
does this number become? If the answer is (close to) 0 second, I'd rephrase: I
don't like having tables that huge in the source code for no reason.
> 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
>
> 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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