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Re: [Bug-gsl] Performance of gsl_rng_uniform_int()
From: |
Markus Armbruster |
Subject: |
Re: [Bug-gsl] Performance of gsl_rng_uniform_int() |
Date: |
Thu, 17 Feb 2005 17:19:13 +0100 |
User-agent: |
Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (gnu/linux) |
Brian Gough <address@hidden> writes:
> Markus Armbruster writes:
> > I remember enough math to be adequately cautious with PRNGs. I may
> > overlook something deep, but isn't
> >
> > (unsigned long)(gsl_rng_uniform (r) * n)
> >
> > a perfectly fine way to get uniformely distributed integers from 0 to
> > n-1 inclusive?
>
> The distribution is technically not uniform if the range of r is not a
> multiple of n.
Hmm. You're right, because floating-point numbers are not real
numbers. The difference matters when n is large. I guess I can use
the faster method for throwing six-sided dice :)