Seeding the pseudo random number generator

yerl <>
Wed Jun 9 02:10:32 CEST 2004


Hi!
Have a look to the Primes numbers generator from Joe's example at 
(http://www.erlang.org/examples/examples-2.0.html).

The seed function is:

new_seed() ->
         {_,_,X} = erlang:now(),
         {H,M,S} = time(),
         H1 = H * X rem 32767,
         M1 = M * X rem 32767,
         S1 = S * X rem 32767,
         put(random_seed, {H1,M1,S1}).

This function generates different numbers each time when it's called.

Good luck.
/yerl


----Message d'origine----
>Date: Fri, 4 Jun 2004 00:18:32 +0300
>De: Einar Karttunen <>
>A: Erlang ML <>
>Sujet: Seeding the pseudo random number generator
>
>Hello
>
>Is there a way to automatically seed the pseudo random number generator?
>Using random:uniform I get allways the same sequence of numbers. I could
>allways seed the generator when my module is called but that does not 
>seem a good idea... And what is the preferred way of seeding the 
>generator? Using erlang:now seems the easiest approach, but the
>generated numbers are not random by any means.
>
>seed() ->
>	{A,B,C} = erlang:now(),
>	random:seed(A,B,C).
>	
>Using /dev/urandom seems possible, but I would like to avoid it if
>possible...
>
>- Einar Karttunen
>
>




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