#include <boost/random.hpp>// Generate a seed in the 'usual' waysrand( time( NULL ) );unsigned long seed = rand();// I chose a Mersenne Twister pseudo-RNG object // but you could have picked any one of a number// of available PRNGs.boost::mt19937 rng( seed ); // generate a random number in the 'usual' range.unsigned long foo = rng(); // uniformly distributed// Create an exponential distribution adapter object,// which will use the random number generator we just// created, and will have a distribution parameter // lambdadouble lambda = 123.4; // for exampleboost::exponential_distribution dist( rng, lambda );// get a random number with the new distributiondouble bar = dist();  // exponentially distributed