Date:	Wed, 16 Feb 2000 08:51:32 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	Dieter Buerssner <buers AT gmx DOT de>
cc:	djgpp AT delorie DOT com
Subject:	Re: Uptime and entropy in DOS
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On 15 Feb 2000, Dieter Buerssner wrote:

> If the random() is used in default mode (rand_type = 3), random()
> seems to be a lagged Fibonacci RNG.

Yes.

> So, if you really need a good RNG, I would suggest to not
> use random(). You might want to do a net search on Marsaglia
> and Mersenne Twister.

`random' is actually quite good.  It is better than `rand', and with
the single exception of the birthday test, it behaves quite well.  It
might be not good enough for George Marsaglia, but I bet nobody else
will notice anything bad ;-)

Of course, if someone needs to write a multidimensional Monte-Carlo
simulation whose results will be used in safety-related applications,
then they had better used the best RNG they can get (and run their
program with several different RNGs to see the difference); these
applications *will* need the latest RNGs by Marsaglia.  I had my
share of such programs, but I doubt if many people here will need
that.

> When rand_type = 0, BSD random produces very bad random numbers
> with an alternating least significant bit.

Yes, but you can only get to this mode if you hack the sources of
`random'.

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