On Mon, Nov 25, 2013 at 11:16 AM, Jérémy Coulon
Hello,
I'm using Boost 1.54. The following code hangs in infinite loop when generating a single floating point number :
#include
#include <iostream> #include <limits> int main() { boost::random::mt19937 rng; boost::random::uniform_real_distribution<float> distrib( -std::numeric_limits<float>::max(), std::numeric_limits<float>::max());
std::cout << distrib(rng) << std::endl; return 0; }
I can reproduce the bug with both - Linux GCC 4.8 x86_64 and - Windows VisualStudio 2012 32bits
It looks like this uniform distribution doesn't work if the range [min,max] is large. From uniform_real_distribution.hpp:61 T result = numerator / divisor * (max_value - min_value) + min_value;
Here the operation (max_value - min_value) produces an overflow.
Regards, Jeremy
It seems to me that it's not really just "large" that is the issue, but only if you have a range larger than std::numeric_limits<float>::max(). Ideally, you'd not really want to be messing with too very many numbers that are within many orders of magnitude of the max float value, as your precision will be awful. Are you just edge-case testing, or do you have a real reason to generate uniform distributions over this range? Brian