25 Numerics library [numerics]

25.6 Random number generation [rand]

25.6.8 Random number distribution class templates [rand.dist]

25.6.8.5 Normal distributions [rand.dist.norm]

25.6.8.5.3 Class template chi_­squared_­distribution [rand.dist.norm.chisq]

A chi_­squared_­distribution random number distribution produces random numbers distributed according to the probability density function
template<class RealType = double>
  class chi_squared_distribution {
  public:
    // types
    using result_type = RealType;
    using param_type  = unspecified;

    // constructor and reset functions
    chi_squared_distribution() : chi_squared_distribution(1) {}
    explicit chi_squared_distribution(RealType n);
    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;
  };
explicit chi_squared_distribution(RealType n);
Requires: .
Effects: Constructs a chi_­squared_­distribution object; n corresponds to the parameter of the distribution.
RealType n() const;
Returns: The value of the n parameter with which the object was constructed.