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Date:      Tue, 4 Feb 2003 15:07:30 +0300
From:      "Andrey A. Chernov" <ache@nagual.pp.ru>
To:        Kris Kennaway <kris@obsecurity.org>, current@FreeBSD.ORG
Subject:   Re: rand() is broken
Message-ID:  <20030204120730.GA91888@nagual.pp.ru>
In-Reply-To: <20030204115237.GA6483@HAL9000.homeunix.com>
References:  <20030202070644.GA9987@rot13.obsecurity.org> <20030202090422.GA59750@nagual.pp.ru> <20030203002639.GB44914@HAL9000.homeunix.com> <20030203100002.GA73386@nagual.pp.ru> <20030204054020.GA2447@HAL9000.homeunix.com> <20030204094659.GA87303@nagual.pp.ru> <20030204115237.GA6483@HAL9000.homeunix.com>

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On Tue, Feb 04, 2003 at 03:52:37 -0800, David Schultz wrote:
> 
> You can do better than the present generator with 32 bits of state.
> See the following page by Neal Wagner (not to be confused with David Wagner):
> 	http://www.cs.utsa.edu/~wagner/laws/rng.html
> The section on LCGs suggests that the multiplier FreeBSD uses (7^5)
> is not particularly good, and points out some better values suggested
> by Knuth.  I can't find the original discussion in TAOCP vol. 2, but

Thank for your pointer, I'll look at later.

> Well, if 0 doesn't work, and 10 doesn't work, and 100 doesn't
> work, then I'm not too hopeful about 2000.  I appeal to Asimov's
> zero, one, infinity law.

I found that f.e. 50 is worse than 100, but 200 isn't better. 100 is 
better than 0 because remove monotonically increased sequence.

-- 
Andrey A. Chernov
http://ache.pp.ru/

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