From:	Thomas Demmer <demmer AT LSTM DOT Ruhr-UNI-Bochum DOT De>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: rand() or random()
Date:	Thu, 06 Nov 1997 09:48:25 +0100
Organization:	Lehrstuhl fuer Stroemungsmechanik
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John Payne wrote:
> 
> Just out of interest, can anybody find to hand the algorithm that GCC uses
> for random(). I'm doing some work on Genetic Algorithms where a fairly
> decent aproximation of randomness is quite important and it would be nice
> to know that's GCC's random() is decent.
> 
> On Wed, 5 Nov 1997, Eli Zaretskii wrote:
> 
> >
> > This doesn't have to be so.  If we have a good free RNG, we could
> > replace `rand'.  Writing a good RNG is not a trivial matter, but
> > there's a lot of literature on the subject, including algorithms and
> > public-domain code, out there.  It shouldn't take somebody who knows
> > about the subject matter more than a few days of work to come up with
> > a reasonably good version.
> >
> > Any takers?
A real good in terms of randomness algorithm can be found in 
one of the 90's Journal of Computational Physics and is by DEK, 
as far as I recall. I involves floating point ops, so it
is probably slower than what is in libc right now. If there
is real need for it, I can go on digging it out.


If you are looking for other good ones, check 
Numerical Recipes by Press/Flannery/Teukolsky/Vetterling, Cambridge
   Press, UK,
Seminumerical Algorithms, DEK, Addison Wesley


-- 
Ciao
Tom

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* Thomas Demmer                                             *
* Lehrstuhl fuer Stroemungsmechanik                         *
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