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Date: Sat, 30 Apr 2011 14:26:16 +0300
From: =?ISO-8859-1?Q?T=F6r=F6k_Edwin?= <edwintorok@gmail.com>
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Subject: Re: [Caml-list] portablility of random.mli in the stdlib

On 04/30/2011 02:14 PM, Christophe Raffalli wrote:
> Le 30/04/11 12:37, Christophe Raffalli a écrit :
>> Hello,
>>
>> Playing with my game (see my previous post), I saw that it seems that
>> the random number generator in not portable ... The same seed will not
>> give the same random sequence on a 32 bits and 64 bits machine ...
>>
> In fact it was a change in random generator in ocaml 3.12
> 
> ------------------------------------
>         Objective Caml version 3.12.0+beta1
> 
> # Random.init 0;;
> - : unit = ()
> # Random.float 1.0;;
> - : float = 0.849294619789682792
> ------------------------------------
>         Objective Caml version 3.11.2
> 
> # Random.init 0;;
> - : unit = ()
> # Random.float 1.0;;
> - : float = 0.454763353840783646
> 
> 
> This means that any long living program should use its own random
> generator ?
> 

Why should a random generator give the same results over multiple
versions and architectures?
Starting from same seed is useful only for debugging.

Best regards,
--Edwin