[
https://issues.apache.org/jira/browse/MATH-650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13099597#comment-13099597
]
Sebb commented on MATH-650:
---------------------------
Yes, I looked at IODH. Turns out that the holder is not required.
Instead, one can use a static class which contains the initial data:
{code}
public class FastMath{
private static class lnMant {
private static final double LN_MANT[][] = {
...
};
...
double d = lnMant.LN_MANT[j][j];
// was double d = LN_MANT[i][j];
}
}
{code}
Very simple to implement; doing that plus commenting out all init code and data
results in speed-up of about 6 times for FastMath.max().
Does not seem to affect performance of method calls once its table(s) has/ve
been loaded.
What remains to be decided is what to do with the init code. Some of it might
be useful in its own right - Taylor expansions for sine/cosine etc.
Perhaps create another class (SlowMath anyone?) in the same package.
And/or move it to the test tree?
> 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
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
