From: ts <decoux@...>
Date: 2000-01-05T14:07:07+01:00
Subject: [ruby-talk:01053] rand() / drand48()



 I was looking at random.c when I've seen that ruby use drand48() when it's
 available. In my documentation of drand48() (debian 2.1) I've :

       The  srand48(),  seed48() and lcong48() functions are ini�
       tialization functions,  one  of  which  should  be  called
       before using drand48(), lrand48() or mrand49().  The func�
       tions erand48(), nrand48() and jrand48() do not require an
       initialization function to be called first.

 If I read it correctly a call to srand48() must be made before any call
 to drand48(). 

 Apparently in random.c, ruby never check if the initialization function
 was called. Can this be a problem for the random generator ?

 It's really easy to forget a call to srand(). For example this script make
 a call to rand() and it's transparent for the user.

pigeon% cat b.rb
#!/usr/bin/ruby
require 'cgi/session'

CGI::Session.new(CGI.new)
pigeon% 


Guy Decoux