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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)