std::exponential_distribution::operator()

// exponential_distribution example
#include <iostream>
#include <chrono>
#include <thread>
#include <random>

int main()
{
  // construct a trivial random generator engine from a time-based seed:
  int seed = std::chrono::system_clock::now().time_since_epoch().count();
  std::default_random_engine generator (seed);

  std::exponential_distribution<double> distribution (1.0);

  std::cout << "ten beeps, spread by 1 second, on average: " << std::endl;
  for (int i=0; i<10; ++i) {
    double number = distribution(generator);
    std::chrono::duration<double> period ( number );
    std::this_thread::sleep_for( period );
    std::cout << "beep!" << std::endl;
  }

  return 0;
}