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https://issues.apache.org/jira/browse/MATH-740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15955303#comment-15955303
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Gilles commented on MATH-740:
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bq. Math.ulp(), Math.IEEEremainder(), Math.getExponent()
Those 3 are implemented in {{FastMath}}.
bq. Math.powerOfTwoD()
What's this?
bq. Also GWT 2.8 supports Math.doubleToLongBits() (probably very slow) but not
Math.doubleToRawLongBits()
I'm lost here; there are no such methods in the JDK's {{Math}} class.
Concerning the subject of this issue (i.e. performance), is someone willing to
start a discussion on the "dev" list?
Practically, we should first set up JMH code to provide performance numbers,
since discrepancies among some "home-made" micro-benchmarking codes were never
explained (nor did they elicit much interest, as strange as it is, given the
heated debate we had about FastMath-related code...).
> Some "FastMath" functions are slow
> ----------------------------------
>
> Key: MATH-740
> URL: https://issues.apache.org/jira/browse/MATH-740
> Project: Commons Math
> Issue Type: Wish
> Reporter: Gilles
> Priority: Minor
> Fix For: 4.0
>
> Attachments: jafamatests.zip
>
>
> From the two benchmarks we currently have in "FastMathTestPerfomance", we
> have that the following functions are much slower in "FastMath" than in
> either "Math" or "StrictMath" (the performance *loss*, for each of the
> benchmarks, is given in parentheses):
> * log10 (46%, 36%)
> * log1p (68%, 112%)
> * tan (11%, 61%)
> * atan (26%, 125%)
> * atan2 (44%, 40%)
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