/* * Chi^2 distribution * * This code has been adapted from RANDLIB.C 1.3, by * Barry W. Brown, James Lovato, Kathy Russell, and John Venier. * Code was originally by Ahrens and Dieter (see above). * * Adapter's notes: */#ifndef BZ_RANDOM_CHISQUARE#define BZ_RANDOM_CHISQUARE#ifndef BZ_RANDOM_GAMMA #include <random/gamma.h>#endifBZ_NAMESPACE(ranlib)template<typename T = double, typename IRNG = defaultIRNG,     typename stateTag = defaultState>class ChiSquare : public Gamma<T,IRNG,stateTag>{public:    typedef T T_numtype;    ChiSquare(T df)      : Gamma<T,IRNG,stateTag>(df/2.0)    {        setDF(df);    }    void setDF(T _df)    {        BZPRECONDITION(_df > 0.0);        df = _df;        Gamma<T,IRNG,stateTag>::setMean(df/2.0);    }    T random()    {        return 2.0 * sgamma();    }protected:    T sgamma()    {        return Gamma<T,IRNG,stateTag>::random();    }    T df;};BZ_NAMESPACE_END#endif // BZ_RANDOM_CHISQUARE