Random.h

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#ifndef GENETIK_UTIL_RANDOM
#define GENETIK_UTIL_RANDOM

#include "Log.h"

namespace genetiK
{
namespace util
{

class Random
{
protected:

        Random();

        virtual ~Random();
private:
        static Random*                  implementation;

public:
        static void                     setImplementation(Random* random);
        
        static void                     setDefaultImplementation();
        
        inline static Random*           getImplementation()
        {
                if (!implementation)
                        Log::getInstance()->warn("Warning: You should call setImplementation before calling Random::getImplentation().");
                return implementation;
        }
        static void                     deleteImplementation();

        virtual unsigned int            getNextInt()=0;
        
        virtual unsigned int            getNextInt(unsigned int max)=0;
        
        virtual double                  getNextReal()=0;

};

/*
*  Random Number generator 'Mersenne Twister'                                *
*                                                                            *
*  This random number generator is described in the article by               *
*  M. Matsumoto & T. Nishimura, in:                                          *
*  ACM Transactions on Modeling and Computer Simulation,                     *
*  vol. 8, no. 1, 1998, pp. 3-30.                                            *
*  Details on the initialization scheme can be found at                      *
*  http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html                  *
*                                                                            *
*  Experts consider this an excellent random number generator.               */

class RandomDefault : public Random{
private:

#if 0
        // constants for MT11213A:
        // (32 bit constants cannot be defined as enum in 16-bit compilers)
        static const unsigned int MERS_N   351
        static const unsigned int MERS_M   175
        static const unsigned int MERS_R   19
        static const unsigned int MERS_U   11
        static const unsigned int MERS_S   7
        static const unsigned int MERS_T   15
        static const unsigned int MERS_L   17
        static const unsigned int MERS_A   0xE4BD75F5
        static const unsigned int MERS_B   0x655E5280
        static const unsigned int MERS_C   0xFFD58000
#else    
        // constants for MT19937:
        static const unsigned int MERS_N = 624;
        static const unsigned int MERS_M = 397;
        static const unsigned int MERS_R = 31;
        static const unsigned int MERS_U = 11;
        static const unsigned int MERS_S = 7;
        static const unsigned int MERS_T = 15;
        static const unsigned int MERS_L = 18;
        static const unsigned int MERS_A = 0x9908B0DF;
        static const unsigned int MERS_B = 0x9D2C5680;
        static const unsigned int MERS_C = 0xEFC60000;
#endif

        unsigned int                            stateVector[MERS_N];
        unsigned short int                      stateVectorIndex;

        unsigned long int                       seed;
public:
        RandomDefault(unsigned int seed);
        virtual ~RandomDefault();
        virtual unsigned int            getNextInt();
        
        virtual unsigned int            getNextInt(unsigned int max);
        
        virtual double                  getNextReal();
};

}
}

#endif

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