BinomialNeg.h

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// Honeycomb, Copyright (C) 2015 NewGamePlus Inc.  Distributed under the Boost Software License v1.0.
#pragma once

#include "Honey/Math/Random/Dist/Poisson.h"

namespace honey
{


template<class Real>
class BinomialNeg_ : public RandomDist<Real>
{
    typedef RandomDist<Real> Super;
    RandomDist_imports();
    template<class> friend class BinomialNeg_;
    typedef typename Numeral<Real>::Int Int;
    typedef Gaussian_<Double>   Gaussian;
    typedef Gamma_<Double>      Gamma;
    typedef GammaFunc_<Double>  GammaFunc;
    typedef Beta_<Double>       Beta;
    typedef Poisson_<Double>    Poisson;
public:
    BinomialNeg_(RandomGen& gen, Real n, Real p)    : RandomDist<Real>(gen), n(n), p(p) { assert(n > 0 && p >= 0 && p <= 1); }

    virtual Real next() const;
    virtual Real pdf(Real x) const;
    virtual Real cdf(Real x) const;
    virtual Real cdfInv(Real P) const;
    virtual Real mean() const                       { return n*(1-p) / p; }
    virtual Real variance() const                   { return n*(1-p) / Alge::sqr(p); }
    

    static Real trialProb(Int x, Real n, Real P);

    Real n;
    Real p;
};

typedef BinomialNeg_<Real>      BinomialNeg;
typedef BinomialNeg_<Float>     BinomialNeg_f;
typedef BinomialNeg_<Double>    BinomialNeg_d;

extern template class BinomialNeg_<Float>;
extern template class BinomialNeg_<Double>;

}