The second one follows the classical definition: normalize frequencies
to add to 1, do the p ln p thing, add em up, and change the sign.
The first one looks like it does a little less work, by some algebraic
manipulation, and might be a little faster.
Henry Rich
On 3/21/2013 8:29 PM, Scott Locklin wrote:
<quote author="Henry Rich">
entropy =: +/@:(* ^.) (^.@] - %) +/
or
entropy =: -@(+/)@:(* ^.)@(% +/)
</quote>
Hot dog! Thank you!
Puzzing this out a bit, the second one makes more sense to me. I can stick
parens and y's in and see what makes it tick. Somehow the fork and the @: in
the first one confuses me on initial inspection (@ seems to work OK too). As I
learn more about forks, perhaps I will feel better about things like this.
mmdow was easy:
mmdow=: entropy + (_1 + #) % 2 * +/
Thanks again fellows! I'll drop another note in this thread when the script is
done enough to share.
-Scott
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