Defined in header <random>  

template< class RealType = double > class chi_squared_distribution;  (since C++11) 
The chi_squared_distribution
produces random numbers x>0 according to the Chisquared distribution: f(x;n) =
x(n/2)1 e^{x/2} 
Γ(n/2) 2n/2 
Γ is the Gamma function (See also std::tgamma
) and n are the degrees of freedom (default 1).
std::chi_squared_distribution
satisfies all requirements of RandomNumberDistribution
.
RealType    The result type generated by the generator. The effect is undefined if this is not one of float , double , or long double . 
Member type  Definition 

result_type  RealType 
param_type  the type of the parameter set, see RandomNumberDistribution . 
constructs new distribution (public member function) 

resets the internal state of the distribution (public member function) 

Generation 

generates the next random number in the distribution (public member function) 

Characteristics 

returns the degrees of freedom (n) distribution parameter (public member function) 

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

returns the minimum potentially generated value (public member function) 

returns the maximum potentially generated value (public member function) 
compares two distribution objects (function) 

performs stream input and output on pseudorandom number distribution (function template) 
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