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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