[
https://issues.apache.org/jira/browse/MATH-1293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15011000#comment-15011000
]
Aleksei Dievskii commented on MATH-1293:
----------------------------------------
OK, I attached the new patch.
> Tabulating the logarithmic factorial
> ------------------------------------
>
> Key: MATH-1293
> URL: https://issues.apache.org/jira/browse/MATH-1293
> Project: Commons Math
> Issue Type: Improvement
> Affects Versions: 3.5
> Reporter: Aleksei Dievskii
> Priority: Minor
> Labels: feature, patch
> Attachments: factlog.patch
>
>
> Presently, CombinatoricsUtils#factorialLog is calculated via a tabulated
> value for the first 21 entries, and for the rest it employs linear-complexity
> direct summing. For the factorial-heavy computations this can be rather
> painful. I propose a patch which allocates additional 16KB of tabulated
> log-factorial values, allowing very fast (constant complexity) computation
> for arguments up to 17000, and delegating to the log-gamma for the rest.
> Benchmarks show a speed-up of up to 200x.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
