[Patches] A bug fix to betavariate() in random.py

[Janne Sinkkonen]

The betavariate() in random.py has nothing to do with beta-distributed
random numbers. Here's something that works:

*** random.py.orig	Fri May 26 16:11:23 2000
--- random.py	Fri May 26 16:12:49 2000
***************
*** 270,280 ****
  # -------------------- beta --------------------
  
  def betavariate(alpha, beta):
  
! 	# Discrete Event Simulation in C, pp 87-88.
! 
! 	y = expovariate(alpha)
! 	z = expovariate(1.0/beta)
  	return z/(y+z)
  
  # -------------------- Pareto --------------------
--- 270,281 ----
  # -------------------- beta --------------------
  
  def betavariate(alpha, beta):
+ 	# Devroye, L. (1986) Non-Uniform Random Variate Generation,
+ 	# theorem 4.1A (p. 430)
+ 	# Bug fix courtesy Janne Sinkkonen <janne@iki.fi>
  
! 	y = gammavariate(alpha,1)
! 	z = gammavariate(beta,1)
  	return z/(y+z)
  
  # -------------------- Pareto --------------------


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-- 
Janne Sinkkonen
<janne@nnets.fi>