29 Numerics library [numerics]

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

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

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

    // constructors and reset functions
    explicit gamma_distribution(RealType alpha = 1.0, RealType beta = 1.0);
    explicit gamma_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 alpha() const;
    RealType beta() const;
    param_type param() const;
    void param(const param_type& parm);
    result_type min() const;
    result_type max() const;
  };