http://qs1969.pair.com?node_id=513306


in reply to Re: Speed/Efficiency tweaks for a fannkuch benchmark script?
in thread Speed/Efficiency tweaks for a fannkuch benchmark script?

That's a mighty good permutation algorithm you're using. I'm curious as to where you came across it. (A few years ago I did a fair bit of investigation into permutation generation, and this algorithm was the fastest pure-Perl one I could find by quite a margin. Your code looks remarkably similar to mine!)
That was a subroutine I had found on the web a while ago when I was looking for how to do fast permutations. I didn't really remember exactly where I got it, (I had stored it away in my folder of cool and interesting perl stuff,) but in looking at your web page, there is little doubt that it was from there. Sorry for not attributing it correctly, and thank you for making it available.

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Re^3: Speed/Efficiency tweaks for a fannkuch benchmark script?
by robin (Chaplain) on Dec 01, 2005 at 16:06 UTC
    No need to be sorry. I'm glad you found it useful!

    In any case, I got the algorithm from a C program posted to alt.sources in 1990 by Matt Day, who I haven't been able to track down.