RandomNumberUtils.h

#ifndef RANDOMNUMBERUTILS_H
#define RANDOMNUMBERUTILS_H

#include "NeuralNetConfig.h"

#include <ctime>
#include <cstdlib>
#include <cmath>

// Utility functions for random numbers.
// Default implementation uses rand(), so
// it should almost certainly be replaced
// with something better!

//namespace nnet added 15/08/06 by Mark Grimes (mark.grimes@bristol.ac.uk) for the LCFI vertex package
namespace nnet
{

namespace NeuralNetRandom {

inline unsigned int GetNewRandomSeed(void)
{
        return (unsigned int)time(NULL);
}

inline void SetRandomSeed(unsigned int seed)
{
        srand(seed);
}

// Uniform random double between 0 and 1
inline double RandomFloat()
{
        return ((double)rand())/(((double)RAND_MAX)+1.0);
}

// Uniform random double between -1 and 1
inline double RandomClamped()
{
        return (RandomFloat()-RandomFloat());
}

// Gaussian random numbers with std. dev. 0.5
inline double RandomGauss()
{
        static int ncalls = -1;
        static double y1;
        static double y2;
        ncalls++;
        if (ncalls%2 ==  0)
        {
                double x1,x2,w;
                do
                {
                        double r1 = RandomFloat();
                        double r2 = RandomFloat();

                        x1 = (2.0*r1)-1.0;
                        x2 = (2.0*r2)-1.0;

                        w = x1*x1 + x2*x2;
                } while (w >= 1.0);
                double u = sqrt(-2.0*log(w)/w);
                y1 = u*x1*0.5;
                y2 = u*x2*0.5;
                return y1;
        }
        else
        {
                return y2;
        }
}

// Uniform random integer between x and y
inline int RandomInt(const int x,const int y)
{
        return rand()%(y-x+1)+x;
}

}

}//namespace nnet

#endif