Subject: Re: ceerano and the seed From: "Peter Lunde" Date: Tue, 17 Sep 2002 00:48:23 -0400 List-archive: List-help: List-id: Midrange Systems Technical Discussion List-post: List-subscribe: , List-unsubscribe: ,

```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

```