[boost] [random] uniform_int isn't uniform

From: David Benbennick (dbenbenn_at_[hidden])
Date: 2006-03-15 09:50:59

Class uniform_int from <boost/random/uniform_int.hpp> is supposed to
provide a uniform random integer distribution on a range [min, max]. 
(See [1].)  It doesn't do that.

I've attached a demonstration program, random.cc.  The program asks
uniform_int for integers in the range [0, 780903144], then sorts those
integers into 20 equal buckets.  If the random integers were uniformly
distributed, the buckets would all get about the same number of
elements.  Instead, the last 5 buckets only get 2/3 as many numbers. 
To put it another way, in this specific case, uniform_int
significantly under-represents the top 1/4 of its range.

I've attached a patch to uniform_int.hpp that fixes the problem.

References:
[1] http://boost.org/libs/random/random-distributions.html#uniform_int