Misc_Random.hpp

/*
 * Misc_Random.hpp
 *
 * Revision: October 2018
 * Author: Thassyo Pinto - thassyo@ieee.org
 *
 * A collection of functions for creating random doubles.
 */

#ifndef MISC_RANDOM_HPP_
#define MISC_RANDOM_HPP_

// Standard libraries
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <iostream>

// Seeds the random number generator with the indicated seed.
inline void seed(unsigned int seed){
#ifdef DEBUG
  std::cout << "Seed set: " << seed << std::endl;
#endif
  srand(seed);
}

// Seeds the random number generator based on the current time.
inline void seed(){
  time_t current_time = time(NULL);
#ifdef DEBUG
  std::cout << "Seeded by time " << current_time << std::endl;
#endif
  srand(current_time);
}

// Returns a random double in the interval [0, 1].
inline double randDouble(){
  double random = (double)rand()/(double)RAND_MAX;
#ifdef DEBUG
  std::cout << "randDouble: " << random << std::endl;
#endif
  return random;
}

// Returns a random double in the interval [0, max].
inline double randDouble(double max){
  double random = randDouble() * max;
#ifdef DEBUG
  std::cout << "randDouble(max): " << random << std::endl;
#endif
  return random;
}

// Returns a random double in the interval [min, max].
inline double randDouble(double min, double max){
  double random = randDouble() * (max - min) + min;
#ifdef DEBUG
  std::cout << "randDouble(min,max): " << random << std::endl;
#endif
  return random;
}

// Returns a random integer in the interval [min, max].
inline int randInt(int min, int max){
  int randomIndex = int(randDouble(min, max));
  while(randomIndex >= max){
    randomIndex = int(randDouble(min, max));
  }
#ifdef DEBUG
  std::cout << "randInt: " << randomIndex << std::endl;
#endif
  return randomIndex;
}

// Returns a random integer in the interval [0, max].
inline int randInt(int max){
  return randInt(0, max);
}

// Gaussian random function to produce a real number according to a Gaussian distribution.
inline double randGaussian(double m=0.0,double v=1.0){
  double factor = sqrt(-2.0f * log(randDouble()));
  float angle  = 2.0f * M_PI * randDouble();
  double random =  double(m + v * factor * cos(angle));
#ifdef DEBUG
  std::cout << "randGaussian: " << random << std::endl;
#endif
  return random;
}

// Generates a random index in the range [min, max].
inline size_t randIndex(size_t min, size_t max){
  size_t randomIndex = size_t(randDouble(min, max));
  while(randomIndex >= max){
    randomIndex = size_t(randDouble(min, max));
  }
#ifdef DEBUG
  std::cout << "randIndex: " << randomIndex << std::endl;
#endif
  return randomIndex;
}

// Generates a random index in the range [0, max].
inline size_t randIndex(size_t max){
  return randIndex(0, max);
}

#endif /* MISC_RANDOM_HPP_ */