std::gamma_distribution<RealType>:: alpha, beta

From cppreference.com
RealType alpha ( ) const ;
(1) (since C++11)
RealType beta ( ) const ;
(2) (since C++11)

Returns the distribution parameters the distribution has been constructed with.

1) Returns the α distribution parameter. It is also known as the shape parameter. The default value is 1.0 .
2) Returns the β distribution parameter. It is also known as the scale parameter. The default value is 1.0 .

Parameters

(none)

Return value

1) Floating point value identifying the α parameter.
2) Floating point value identifying the β parameter.

See also

(C++11)
gets or sets the distribution parameter object
(public member function)