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https://issues.apache.org/jira/browse/MATH-650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13206119#comment-13206119
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Sébastien Brisard commented on MATH-650:
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Hi Luc,
thanks for taking care of this difficult issue. I would lean on the binary
side, for "safety" reasons: unwanted modifications are less likely to occur.
But I do realize that this can be endlessly debated over, and to be really
honnest, I would be very happy with either solution (or even the runtime
computation: as far as I am concerned, the typical timing of my computations is
about 1 hour to one week... plenty of seconds...).
If we opt for the binary option, maybe we could provide a binary-to-ascii
method, for anyone to check the data (maybe that's already available).
I'm surprised though that binary files take longer to load than litteral. I
should have thought that reading a presumably longer table, and parsing a
presumably larger number of octets for each double would result in a longer
loading time. I must have missed something.
> 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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