Beowulf Questions

Donald Becker becker at
Sat Jan 4 09:29:40 PST 2003

On Sat, 4 Jan 2003, Florent.Calvayrac wrote:

> > This is trivial.  Once you get a good a serial pseudo-random number
> > generator, you can use a cluster to generate more.
> Sorry to disagree here, but you forget that you can not be sure
> that the initial seed on one of the machines will not
> be generated by another you can end up with
> completely correlated series. Check "scalable parallel number
> generator" (sprng), working well for us, using different
> recurrence formulas on different machines.

I was assuming a sophisticated RNG.  With such, the likelyhood of
identical seeds is very low, exactly the same as correlation within the
number stream.  Anyone that needs a cluster to generate random numbers
will be far beyond using a LFSR with a small seed.

I'll even put forth a hand-waving argument that multiple machines will
be working from a much richer entropy pool, and thus generate better
quality numbers.

Donald Becker				becker at
Scyld Computing Corporation
410 Severn Ave. Suite 210		Scyld Beowulf cluster system
Annapolis MD 21403			410-990-9993

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