rng.cpp

#include <cassert>
#include "rng.h"

namespace utils
{
  namespace rand
  {
    // The definition of variable rng, declared in rng.h
    Rng rng(static_cast<unsigned>(std::random_device()()));

    // The definitions of the functions declared in rng.h
    void seedRand(uint_fast32_t seed)
    {
      rng.seed(seed);
    }

    int randInt(int rangeBegin, int rangeEnd)
    {
      // Function to produce a random integer in [rangeBegin, rangeEnd).
      assert(rangeEnd > rangeBegin);
      std::uniform_int_distribution<> dist {rangeBegin, rangeEnd - 1};
      return dist(rng);
    }

    double randDouble(double rangeBegin, double rangeEnd)
    {
      // Function to produce a random double in [rangeBegin, rangeEnd).
      std::uniform_real_distribution<> dist {rangeBegin, rangeEnd};
      return dist(rng);
    }

    double randNormal(double mean, double stdev)
    {
      // Function to produce a random normally distributed double.
      std::normal_distribution<> dist {mean, stdev};
      return dist(rng);
    }

    bool randBool()
    {
      // Function to produce a random bool
      static std::bernoulli_distribution dist;  // Default probability is 0.5.
      return dist(rng);
    }
  }
}