[Octave-bug-tracker] [bug #61199] Allow 'char' input sets to nchoosek for Matlab compatibility

[Rik]

Follow-up Comment #36, bug #61199 (project octave):

I did some more benchmarking and checked in the final changeset here:
http://hg.savannah.gnu.org/hgweb/octave/rev/f5aba4d7e651.

Benchmark times (in microseconds)

Original code: 113
New code w/gcd loop: 484
New code w/gcd loop & pairwise multiplication: 371
New code w/gcd loop, pairwise multiplication, factor 2 removal: 339

I was able to get another 8.5% improvement by realizing that pairwise
multiplication of an odd and an even number will always produce an even
number.  Hence, one can take out a factor of 2 immediately from the numerator
and denominator.

Overall, I'm happy with the result.  It is more accurate and no human is going
to notice the difference between 0.1 millisecond and 0.3 milliseconds given
that reaction times are on the order of 750 milliseconds.

I'm ready to close this bug if everyone else is.

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