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From: "John B. Matthews" <nospam@nospam.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Random number generation
Date: Wed, 14 Jul 2010 00:42:39 -0400
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In article <i1irmb$vfe$1@tornado.tornevall.net>,
 "Jeffrey R. Carter" <spam.jrcarter.not@spam.acm.org> wrote:

> On 07/13/2010 01:33 PM, John B. Matthews wrote:
> >
> > The shuffling algorithm needs work; this might be an alternative:
> >
> > <http://en.wikipedia.org/wiki/Fisher–Yates_shuffle>
> 
> The problem with this (for Ada) is the need to instantiate 
> Discrete_Random for a different range each time (although you could 
> use PragmARC.Universal_Random.Random_Int).

Thank you for suggesting this; I see the problem, now. Section 
A.5.2(50), Note 16, mentions the very problem, suggesting Float_Random 
as an alternative:

<http://www.adaic.com/standards/05rm/html/RM-A-5-2.html>

I also found this implementation using Discrete_Random:

<http://rosettacode.org/wiki/Knuth_shuffle#Ada>

> If it's for a game with a human, then the biased version of using the 
> full range each time is good enough.

No, it's a simulation; I don't get off that easy.
 
> > As an aside, Mine Detector V6.0 builds on Mac OS X 10.5.8 with GtkAda
> > 2.14.1 and GNAT 4.3.4. Wait, I took a picture:
> >
> > <http://i26.tinypic.com/23qyxxi.png>
> 
> Cool. I wouldn't check any boxes with only 100 mines.

They were smiling for the camera! :-)

-- 
John B. Matthews
trashgod at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>