Difference between Matlab and Octave in random seeding

[Michael Creel]

The need for controlling how seeding is done is not different, nor is the
need to be aware of the change. However, the change makes life more
difficult and error-prone, I think, which is why I registered a vote against
it.
Cheers, Michael

On Fri, Mar 7, 2008 at 3:44 PM, Bateman David-ADB014 <
David.Bateman at motorola.com> wrote:

>
> The change that was made results in separate seeds for the rand, rand,
> rande, randg and rande generators.. The other generators in the statistics
> toolbox rely on these five intrinsic generators and so will of cause now be
> seeded differently.
>
> However, I'm not sure I see the need for seeding in a parallel situation
> being any different from the normal case. The programmer needs to be aware
> of the change in both cases.
>
> BTW, the old generators had/have seperate seeds, and the change makes the
> behavior of seeding with 'state' or 'seed' similar.
>
>
> -----Original Message-----
> From: michael.creel at gmail.com on behalf of Michael Creel
> Sent: Fri 07-Mar-08 9:27 AM
> To: John W. Eaton
> Cc: bug-octave at octave.org
> Subject: Re: Difference between Matlab and Octave in random seeding
>
> On Thu, Mar 6, 2008 at 6:49 PM, John W. Eaton <jwe at bevo.che.wisc.edu>
> wrote:
>
> > On  5-Mar-2008, Michael Creel wrote:
> >
> > | On this issue, I vote for having the seed set in a single spot for all
> > RNGs.
> > | This facilitates greatly parallel use of Octave. Sometimes it's
> > important to
> > | be able to reset the seed, and it's a lot less likely to screw up if
> > only
> > | one needs to be reset.
> >
> > I guess I'm missing something because I don't see how having separate
> > states for rand and randn has anything to do with parallelism.
> >
> > jwe
>
>
> It doesn't have any intrinsic effect, of course, but from the point of
> view
> of ease of programming and likelihood of making hard to detect errors, it
> is
> not neutral. If RNG has its own seed, then the programmer must control the
> value of that seed on each node. If two RNGs that originally share a seed
> become endowed with separate seeds in a new version of Octave, the
> programmer must be aware of this. If he or she is not, the code will
> continue to run, but with bogus results. If we're only talking about
> having
> one or two seeds for uniform and normal, it's not that big of a deal. But
> if
> RNGs for other distributions also go this route, it will be an
> inconvenience. Basically, I find that the current situation with one seed
> for all RNGs is ideal. Just my 2 euro cents.
> Michael
>
>
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