29 Numerics library [numerics]

29.6 Random number generation [rand]

29.6.8 Random number distribution class templates [rand.dist] Normal distributions [rand.dist.norm] Class template chi_­squared_­distribution [rand.dist.norm.chisq]

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


template<class RealType = double>
  class chi_squared_distribution {
    // 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;

explicit chi_squared_distribution(RealType n = 1);

Requires: 0<n.

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.