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#ifndef SIMPLERNG_H

#define SIMPLERNG_H

// A simple random number generator based on George Marsaglia's MWC (Multiply With Carry) generator.

// This is not intended to take the place of the library's primary generator, Mersenne Twister.

// Its primary benefit is that it is simple to extract its state.

// Source: http://www.johndcook.com/cpp_random_number_generation.html

class SimpleRNG

{

public:

    SimpleRNG();

    // Seed the random number generator 

    void SetState(unsigned int u, unsigned int v);

    // Extract the internal state of the generator

    void GetState(unsigned int& u, unsigned int& v);

    // A uniform random sample from the open interval (0, 1) 

    double GetUniform();

    // A uniform random sample from the set of unsigned integers 

    unsigned int GetUint();

    // This stateless version makes it more convenient to get a uniform 

    // random value and transfer the state in and out in one operation.

    double GetUniform(unsigned int& u, unsigned int& v);

    // This stateless version makes it more convenient to get a random unsigned integer 

    // and transfer the state in and out in one operation.

    unsigned int GetUint(unsigned int& u, unsigned int& v);

    // Normal (Gaussian) random sample 

    double GetNormal(double mean, double standardDeviation);

    // Exponential random sample 

    double GetExponential(double mean);

        // Gamma random sample

    double GetGamma(double shape, double scale);

        // Chi-square sample

    double GetChiSquare(double degreesOfFreedom);

        // Inverse-gamma sample

    double GetInverseGamma(double shape, double scale);

        // Weibull sample

    double GetWeibull(double shape, double scale);

        // Cauchy sample

    double GetCauchy(double median, double scale);

        // Student-t sample

    double GetStudentT(double degreesOfFreedom);

    // The Laplace distribution is also known as the double exponential distribution.

    double GetLaplace(double mean, double scale);

        // Log-normal sample

    double GetLogNormal(double mu, double sigma);

        // Beta sample

    double GetBeta(double a, double b);

        // Poisson sample

        int GetPoisson(double lambda);

private:

    unsigned int m_u, m_v;

        int PoissonLarge(double lambda);

        int PoissonSmall(double lambda);

        double LogFactorial(int n);

};

#endif