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Posted to issues@commons.apache.org by "Sebb (Issue Comment Edited) (JIRA)" <ji...@apache.org> on 2011/10/10 12:22:29 UTC
[jira] [Issue Comment Edited] (MATH-688) "FastMath" contains
fractions of constants
[ https://issues.apache.org/jira/browse/MATH-688?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13123811#comment-13123811 ]
Sebb edited comment on MATH-688 at 10/10/11 10:22 AM:
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bq. the downside will be that these constants will be computed at the loading of "FastMath"
AFAIK, the constant calculations will be done at compile time.
was (Author: sebb@apache.org):
AFAIK, the calculations will be done at compile time.
> "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 (on my machine) to something like 370 ms for 10 million computations.
> And, of course, the downside will be that these constants will be computed at the loading of "FastMath", leading to an additional penalty of about 16 divisions at initialization... :)
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