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From "Gilles (Created) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MATH-688) "FastMath" contains fractions of constants
Date Sun, 09 Oct 2011 00:25:29 GMT
"FastMath" contains fractions of constants
------------------------------------------

                 Key: MATH-688
                 URL: https://issues.apache.org/jira/browse/MATH-688
             Project: Commons Math
          Issue Type: Improvement
            Reporter: Gilles
            Assignee: Gilles
            Priority: Trivial
             Fix For: 3.0


Fractions such as 1.0 / 3.0, 1.0 / 5.0, ... could be replaced with static final constants.
In "asinh", for example, the change can sometimes result in more than halving the computation
time (when the argument is in the range of values where the constants are used).

In absolute times, the gain is not huge, amounting to something like 5 ms for 10 million computations.

And, of course, the downside will be that these values will be computed at the loading of
"FastMath", leading to an additional penalty of about 16 divisions at initialization... :)


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