std::fisher_f_distribution<RealType>:: fisher_f_distribution

From cppreference.com
fisher_f_distribution ( ) : fisher_f_distribution ( 1.0 ) { }
(1) (since C++11)
explicit fisher_f_distribution ( RealType m, RealType n = 1.0 ) ;
(2) (since C++11)
explicit fisher_f_distribution ( const param_type & params ) ;
(3) (since C++11)

Constructs a new distribution object.

2) Uses m and n as the distribution parameters.
3) Uses params as the distribution parameters.

Parameters

m - the m distribution parameter (degrees of freedom)
n - the n distribution parameter (degrees of freedom)
params - the distribution parameter set

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
P0935R0 C++11 default constructor was explicit made implicit