[plt-scheme] Does SRFI-27 specify repeatable PRNGs?

Actually, SRFI 27 specifies repeatable random sources.  You have to call
random-source-randomize! to get different ones.  And, there is a
random-source-pseudo-randomize! procedure that gives you multiple,
independent, repeatable random sources.  There are also routines in the
science collection to create vectors of independent random sources.

Doug

On Jan 2, 2008 10:21 AM, Chongkai Zhu <czhu at cs.utah.edu> wrote:

> Erich Rast wrote:
> > Hi,
> >
> > Sorry, I know this is a bit off-topic, but perhaps someone here has
> > already stumbled across the answer. I'm looking for a good PRNG that
> > is portable, but it needs to be one that allows me to get exactly the
> > same PRN sequence from the same seed.
> >
> > Can I use SRFI-27 for that purpose or does it only specify the
> > interface to possibly different PRNGs that might produce different
> > sequences?
> >
>
> SRFI-27 only specifies the interface to possibly different PRNGs that
> might produce different sequences. But the reference implementation of
> SRFI 27 is portable and allows you to get exactly the same PRN sequence
> from the same seed.
>
> > How about the built-in generator of MzScheme, might it change in
> > future or is it part of the specs that it won't change under the hood?
> >
>
> Matthew just changed the built-in generator of MzScheme, as a result of
> a discussion here a few days ago. The SRFI 27 implementation in SVN
> (v399) is build on top of the built-in generator, and produces the same
> sequence as the reference implementation of SRFI 27.
>
> > Best,
> >
> > Erich
> >
> Chongkai
>
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