id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
7020,uniform_01 improvement,agribov_no_s_p_a_m@…,No-Maintainer,"The current code to simulate uniform random number in interval [0;1] contains verification to skip 1.

  if (result < result_type(1))
    return result;

It means that random generator can generate 0 but not 1. This is used in some other code, for example, generate Exponential random number:

  return -result_type(1) /
    _lambda * log(result_type(1)-uniform_01<RealType>()(eng));

Meaning (1 - random number) will never be 0.

If eng() returns integer number, then, with some limitations for result_type and generated range of random numbers (result_type has to be double for generated 32 bit random numbers):

  result_type factor = result_type(1) / (result_type((eng.max)()-(eng.min)()) + result_type(1));

  return (result_type(eng() - (eng.min)()) + result_type(0.5)) * factor;
  
In this case, the result will never contain 0 or 1 and will be unbiased. No more checking for 0 or 1 is necessary. 
",Bugs,closed,To Be Determined,random,Boost 1.49.0,Optimization,invalid,uniform_01,