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To: Damien Doligez <Damien.Doligez@inria.fr>
cc: caml-list@inria.fr
Subject: Re: Random.int on non unix platform 
In-reply-to: Your message of "Wed, 26 May 1999 14:07:19 +0200."
             <199905261207.OAA17846@tobago.inria.fr> 
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Date: Tue, 29 Jun 1999 01:35:31 +0300
From: Martin Quinson <mquinson@zeppelin-cb.de>
Message-Id: <E10ykw0-0001U5-00@nestor>
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> >From: Martin Quinson <mquinson@zeppelin-cb.de>
> =

> >How can I write this without the unix library ?
> >
> >Random.init (int_of_float (Unix.time ()));;
> =

> You can do:
> =

>     Random.init (int_of_float (Sys.time ()));;
> =

> or you can input a random seed from the user and give it as argument
> to Random.init.


                        (francais en bas)

hmmm. from htmlman/module sys :

> val time: unit -> float
>
>          Return the processor time, in seconds, used by the program sin=
ce the
> beginning of execution.

So, if this call is at the begining of the programm, it will allways gene=
rate =

the same number (or almost). from the random.ml source code :
(* Simple initialisation.  The seed is an integer.
   Two seeds that are close enough will not produce uncorrelated
   pseudo-random sequences.
*)

And I really dislike the second solution...

Maybe would it be possible to make the module Random initialize itself al=
one =

before the first call, in the next release...


                             [en francais]

J'aimerais initialiser le generateur aléatoire de nombre sans utiliser =
la =

librairie Unix. Dans d'autres langage, j'ai l'habitude d'utiliser l'heure=
 pour =

ca, mais, apparament, c'est impossible sans la librairie Unix (ce qui n'e=
st =

pas portable, oblige a recompiler le top-level et complique la ligne de =

compilation des compilateurs)

Quant à l'idée de demander une graine à l'utilisateur, je trouve ca=
 un peu =

préhistorique, comme approche. ;)

A mon avis, le plus simple serait encore que le module Random se charge t=
out =

seul comme un grand de s'initialiser sans demander a l'utilisateur de le =
faire.
(dans une prochaine version ?)

Merci & thanks,
Martin.