Re: [Boost-users] Boost.Random Generator ignores seed

Subject: Re: [Boost-users] Boost.Random Generator ignores seed
From: Juan Antonio Farré Basurte (jafb_at_[hidden])
Date: 2010-11-14 09:59:12

 On Sun 14/11/10 00:32 , Alex Hagen-Zanker ahh34_at_[hidden] sent:
 > I'm using mt19937 random number generator, belonging to Boost.Random
 >library, and it looks to ignore my call to seed.
 > I show relevant code.
 >
 > static mt19937 gen;
 > static MiniUni cien(1, 100);
 > static variate_generator d100(gen, cien);
 >
 > int main() {
 > {
 > struct timeval time;
 > gettimeofday(
 > gen.seed(time.tv_usec);
 > }
 >
 > And it generates the same sequence over and over. I've double-checked
 >that time.tv_usec really changes.

 Could it be that variate_generator d100(gen, cien) defaults to 
 variate_generator d100(gen,cien) whereas you really need 
 variate_generator d100(gen,cien)?

 The constructor of the variate_generator now makes a copy of gen and 
 changing the seed of gen afterwards does not affect the
variate_generator.

 Solution: explicitly use variate_generator