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From: mhx@iae.nl (mhx)
Newsgroups: comp.lang.forth
Subject: Re: KISS 64-bit pseudo-random number generator
Date: Mon, 9 Sep 2024 10:04:20 +0000
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On Mon, 9 Sep 2024 8:55:14 +0000, Anton Ertl wrote:

>> 1320>> : RANDOM        seed  $107465 *  $234567 +  ( -- u )
>> 1321:                  9 ROL DUP TO seed ;
>
> So this is a linear congruential generator enhanded with the 9 ROL.
> LCGs have known weaknesses that are relevant even for
> non-cryptographic applications.  Maybe the ROL fixes those; have you
> run it through ransomness testers?

The ROL fixes the problem that the lower bits are "less random" than
the higher ones (which was npticeable in my graphics applications). With
9 ROL the generator passes Marsaglia's DIEHARD tests (I showed these
in an ancient post). However, I see a comment in the source that
suggests it did not pass a better test than DIEHARD, so that is why
there are RANF, RAN-NEXT, KISS, pseudo-DES, ran0, ran1, ran2, ran3,
random3, wurst-rng, isaac, lehmer, mersenne-twister, and some I can't
find right now.

-marcel