RE: "Reference #"

["Booth Martin" <Booth@xxxxxxxxxxxx>]

Oh, I am sorry Buck.  

Of course it will select duplicate numbers from time to time, but not very
often.  The *ADD trigger program would look for an error on the add, and get
another random number.  No big deal since it seldom happens.  With any
sequencing scheme you always have a open/update/close to some data storage
somewhere.  Why bother?
 
---------------------------------------------------------
Booth Martin   http://www.MartinVT.com
Booth@xxxxxxxxxxxx
---------------------------------------------------------
 
-------Original Message-------
 
From: RPG programming on the AS400 / iSeries
Date: Friday, March 28, 2003 15:02:15
To: RPG programming on the AS400 / iSeries
Subject: RE: "Reference #"
 
>Then pseudorandom is fine. 

Pseudorandom does NOT mean unique. It means unpredictable (within
mathematically provable limits.) No matter how large the number (even 31
digits), the algorithm can easily produce a sequence like 1, 4509876, 1. It
may not repeat a number as quickly as that, but it WILL repeat a number (not
the sequence of numbers) sooner than a sequential 31 digit number will. The
math to prove that is somewhat above my head, but then a lot of things are.

An example might work better. We have a 1 digit number (0-9). The
algorithm emits a number: 2. The next number does not come from a universe
of 0,1,3,4,5,6,7,8,9 but from the exact same universe of 0-9. The algorithm
might emit a 2, or it might not; you can't predict.
--buck
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