Thus spake Andrey A. Chernov <[EMAIL PROTECTED]>:
> On Mon, Feb 03, 2003 at 21:40:20 -0800, David Schultz wrote:
> I don't try to make rand() good for high-quality pseudo-randomness,
> because it can be done by price of speed and, more important, big state
> size. Due to rand_r() restriction state size can be one word only, so we
> can choose rand() algorithm only from those which pass this
> restrictions.
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
I take N. Wagner's word that the numbers have been blessed by the holy
hand of Knuth. I'm sure you can find more information if you search
the literature. I apologize, but I don't have time to help you right
now, and rand() isn't really a concern to me.
> Returning to current algorithm, I am interested in good NSHUFF value in
> the range 100-2000. Do you have any findings there?
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.
To Unsubscribe: send mail to [EMAIL PROTECTED]
with "unsubscribe freebsd-current" in the body of the message
