[Haskell-cafe] fast integer base-2 log function?
ryani.spam at gmail.com
Fri Feb 15 12:21:52 EST 2008
On Thu, Feb 14, 2008 at 8:23 PM, Uwe Hollerbach <uhollerbach at gmail.com> wrote:
> Stefan's routine is, as expected, much much faster still: I tested the
> first two routines on numbers with 5 million or so bits and they took
> ~20 seconds of CPU time, whereas I tested Stefan's routine with
> numbers with 50 million bits, and it took ~11 seconds of CPU time.
This seems wrong to me; that routine should take a small constant
amount of time. I suspect you are measuring the time to construct the
50-million bit numbers as well. If you constructed a single number
and called this routine on it several times I am sure you would get
far different results, with the first routines taking ~7-11s each and
Stefan's GHC/GMP-magic taking almost nothing.
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