My first thought is that you probably shouldn't reinitialize the generator for every random number you need. I would recommend that you create and seed "generator" once at the start of your program, then reuse it whenever you need a random number.
Perhaps something like the following:
namespace Random
{
typedef boost::minstd_rand base_generator_type;
typedef boost::uniform_int<> distribution_type;
typedef boost::variate_generator gen_type;
//Declare the generator as a global variable for easy reuse
base_generator_type generator(static_cast<unsigned long>(clock()));
/***************************************************
* initializes the random number generator *
**************************************************/
void initialize()
{
for (int i = 0; i < 30000; ++i)
generator.seed(static_cast<unsigned long>(clock()));
}
/***************************************************
* generates a random number between a and b *
* @param a the starting range *
* @param b the integer ending range *
* @return N such that a <= N <= b *
**************************************************/
template <class T>
T rand_int (const T& a, const T& b)
{
//Check the parameters
BOOST_STATIC_ASSERT(boost::is_integral<T>::value);
assert (b >= a);
//Set up the desired distribution
gen_type ran_gen(generator, distribution_type(a, b));
//Get a random number
return ran_gen();
}
}
using Random::rand_int;
int main(int argc, char* argv[])
{
Random::initialize();
std::cout << rand_int (1,1000) << std::endl
<< rand_int (1,1000) << std::endl
<< rand_int (1,1000) << std::endl
<< rand_int (1,1000) << std::endl;
return 0;
}
________________________________________
From: chun ping wang [mailto:cablepuff@gmail.com]
Sent: Friday, May 19, 2006 3:55 AM
To: boost-users@lists.boost.org
Subject: [Boost-users] Newbie question: Random numbers.
I have a simple question, is there a very fast and effecient way to generate random numbers that are fast on the fly. The numbers are really randomize and distorted...
/***************************************************
* generates a random number between a and b *
* @param a the starting range *
* @param b the integer ending range *
* @return N such that a <= N <= b *
**************************************************/
template <class T>
T randint(const T& a, const T& b)
{
BOOST_STATIC_ASSERT(boost::is_integral<T>::value);
assert (b >= a);
typedef boost::minstd_rand base_generator_type;
typedef boost::uniform_int<> distribution_type;
typedef boost::variate_generator gen_type;
base_generator_type generator(boost::numeric_cast<unsigned long>(clock()));
gen_type ran_gen(generator, distribution_type(a, b));
for (int i = 0; i < 30000; ++i)
generator.seed(boost::numeric_cast<unsigned long>(clock()));
return ran_gen();
}
This works but is super slow... are there effective ways to do it...
Thanks.
Andrew Holden