29 Numerics library [numerics]

A chi_­squared_­distribution random number distribution produces random numbers x>0 distributed according to the probability density function

$$p\left(x|n\right)=\frac{x^{\left(n/2\right)-1}\cdot e^{-x/2}}{\Gamma \left(n/2\right)\cdot 2^{n/2}}\text{.}$$

template<class RealType = double>
  class chi_squared_distribution {
  public:
    // types
    using result_type = RealType;
    using param_type  = unspecified;

    // constructor and reset functions
    explicit chi_squared_distribution(RealType n = 1);
    explicit chi_squared_distribution(const param_type& parm);
    void reset();

    // generating functions
    template<class URBG>
      result_type operator()(URBG& g);
    template<class URBG>
      result_type operator()(URBG& g, const param_type& parm);

    // property functions
    RealType n() const;
    param_type param() const;
    void param(const param_type& parm);
    result_type min() const;
    result_type max() const;
  };