Random.h

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/*      
 * File: Random.h
 * Project: DUtils library
 * Author: Dorian Galvez-Lopez
 * Date: April 2010, November 2011
 * Description: manages pseudo-random numbers
 * License: see the LICENSE.txt file
 *
 */

#pragma once
#ifndef __D_RANDOM__
#define __D_RANDOM__

#include <cstdlib>
#include <vector>

namespace DUtils {

class Random
{
public:
  class UnrepeatedRandomizer;
  
public:
        static void SeedRand();
        
        static void SeedRandOnce();

        static void SeedRand(int seed);

        static void SeedRandOnce(int seed);

        template <class T>
        static T RandomValue(){
                return (T)rand()/(T)RAND_MAX;
        }

        template <class T>
        static T RandomValue(T min, T max){
                return Random::RandomValue<T>() * (max - min) + min;
        }

        static int RandomInt(int min, int max);
        
        template <class T>
        static T RandomGaussianValue(T mean, T sigma)
        {
    // Box-Muller transformation
    T x1, x2, w, y1;

    do {
      x1 = (T)2. * RandomValue<T>() - (T)1.;
      x2 = (T)2. * RandomValue<T>() - (T)1.;
      w = x1 * x1 + x2 * x2;
    } while ( w >= (T)1. || w == (T)0. );

    w = sqrt( ((T)-2.0 * log( w ) ) / w );
    y1 = x1 * w;

    return( mean + y1 * sigma );
        }

private:

  static bool m_already_seeded;
  
};

// ---------------------------------------------------------------------------

class Random::UnrepeatedRandomizer
{
public:

  UnrepeatedRandomizer(int min, int max);
  ~UnrepeatedRandomizer(){}
  
  UnrepeatedRandomizer(const UnrepeatedRandomizer& rnd);
  
  UnrepeatedRandomizer& operator=(const UnrepeatedRandomizer& rnd);
  
  int get();
  
  inline bool empty() const { return m_values.empty(); }
  
  inline unsigned int left() const { return m_values.size(); }
  
  void reset();
  
protected:

  void createValues();

protected:

  int m_min;
  int m_max;

  std::vector<int> m_values;

};

}

#endif