RE: ceerano and the seed -- MIDRANGE-L

 Would some one want to post sample code (RPG or CL) for the API CEERAN0?

 ---
Doug Hart


> -----Original Message-----
> From: midrange-l-admin@midrange.com
> [mailto:midrange-l-admin@midrange.com]On Behalf Of Vernon Hamberg
> Sent: Tuesday, September 17, 2002 8:45 AM
> To: midrange-l@midrange.com
> Subject: Re: ceerano and the seed
>
>
> Peter
>
> Would it make sense to treat a user-supplied seed the same way,
> since it is
> limited to a 4-byte signed integer?
>
> BTW, what does the expression "multiplicative congruential" mean?
> The first
> word is simple enough. Are all forms of this kind of generator essentially
> the same, just different constants? I've seen things on the net about
> 2^31-1 and 2^61-1 (or something like that)
>
> I seem to recall problems with skewed distributions when generating
> integers between 2 values. Does this "bucketizing" diminish the quality of
> the distribution? The random number generator actually returns values
> between 0 and 1.
>
> Thanks
>
> At 12:48 AM 9/17/02 -0400, you wrote:
> >Vernon,
> >
> >Yes, I am talking about the theory of generating pseudorandom numbers.
> >
> >I did a lot of work with these when I was doing Processing Plant
> Simulations
> >and Statistical Process Control a long time ago with General Foods.
> >
> >So, hopefully CEERAN0 uses GMT in the form HHMMSSTHT and then
> multiplies by
> >8 and adds 1 to get a large odd seed (since odd numbers have a chance of
> >being prime).
> >
> >Peter.
> >
> >----- Original Message -----
> >From: "Vernon Hamberg" <vhamberg@attbi.com>
> >To: <midrange-l@midrange.com>
> >Sent: Tuesday, September 17, 2002 12:05 AM
> >Subject: Re: ceerano and the seed
> >
> >
> > > Peter
> > >
> > > I'm not sure of the context. The usage instructions for
> CEERAN0 say that
> > > the seed should be a non-negative integer between 0 and 2,147,483,646.
> >Zero
> > > makes it generate its own seed from the GMT at the time the
> function is
> > > called. And it returns a value that can be used as the next seed. Of
> > > course, the new seed is generated by the original process,
> hence, as Leif
> > > says, it might not be that good an idea to use it. That was why I
> >suggested
> > > using 0, as that forces a somewhat unpredictable value for
> the seed each
> >time.
> > >
> > > Are you speaking of the theory of generating pseudorandom
> numbers, that
> > > uses a couple large relatively prime numbers? Am I anywhere
> close? I've
> > > never studied the theory that closely, I just want a function
> I can use
> > > that I can trust to generate even distributions.
> > >
> > > The rand() function in SQL can take a seed or not. Without a seed (a
> > > smallint or integer) it must generate its own seed, as it
> starts with a
> > > different sequence each time. If you use a seed, such as
> rand(100), the
> > > sequence of random floating point numbers is the same each time, as is
> > > expected. CEERAN0 has the same behavior
> > >
> > > Vern
>
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