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https://issues.apache.org/jira/browse/MATH-375?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12904042#action_12904042
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Luc Maisonobe commented on MATH-375:
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The FastMath class has been added to the subversion repository, as of r990655
for branch 2.X and as r990658 for trunk.
It is now used everywhere in the library (including in tests), in replacement
of java.util.Math.
The contributed patch has been edited to match commons-math coding style which
is enforced by checkstyle. The corresponding changes are mainly basic
formatting (spaces, braces ...), naming conventions, variables declarations on
separate lines, javadoc everywhere ... Some javadoc have been marked as "To Be
Confirmed" (exp and log), please have a llook at it and check if they are
correct.
In order to let users do global search and replace of java.util.Math by the new
class, several new methods have been added. For the new functions (sinh, cosh
...) basic implementations have been set up. These implementations should be
about 3 ULP accurate and may be slow for now. For consistency, the inverse
hyperbolic functions (asinh, acosh and atanh) have been added too, depite they
are not present in java.util.Math.
The unit tests have not been committed to the subversion repository yet, we are
waiting for the dfp library to be available and integrated too (otherwise the
continuous integration process would be broken by the missing dependency). This
issue will be marked as resolved when the tests will be committed.
Thanks again for this contribution.
> Elementary functions in JDK are slower than necessary and not as accurate as
> they could be.
> -------------------------------------------------------------------------------------------
>
> Key: MATH-375
> URL: https://issues.apache.org/jira/browse/MATH-375
> Project: Commons Math
> Issue Type: New Feature
> Environment: JDK 1.4 - 1.6
> Reporter: William Rossi
> Fix For: 2.2
>
> Attachments: atanpatch.txt.gz, FastMath.tar.gz
>
>
> I would like to contribute improved versions on exp(), log(), pow(), etc. to
> the project. Please refer to this discussion thread
> http://markmail.org/message/zyeoguw6gwtofm62.
> I have developed over the past year a set of elementary functions similar to
> those in java.lang.Math, but with the following characteristics:
> * Higher performance.
> * Better accuracy. Results are accurate to slightly more that +/- 0.5 ULP.
> * Pure Java. The standard Math class is impleneted via JNI, and thus takes a
> performance hit.
> Note that some functions such as exp are nearly twice as fast in my
> implementation. I've seen it 3 times faster on different processors. The
> preformance varies by the relative speed of calculation vs memory lookups.
> The functions are implemented as tables of values in extra precision (approx
> 70 bits), and then interpolated with a minimax polynomial.
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