std::chi_squared_distribution<RealType>:: chi_squared_distribution

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

Constructs a new distribution object.

2) Uses n as the distribution parameter.
3) Uses params as the distribution parameter.

Parameters

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