gamma_distribution::operator()
Returns a random value.
template<class Engine>
result_type operator()(Engine& eng);
template<class Engine>
result_type operator()(Engine& eng,
const param_type& par0);
Parameters
Engine
The type of the random engine.eng
The random engine.par0
The parameter package used to return the random value.
Remarks
The first member function uses the engine eng as a source of uniformly distributed random values and returns values with a probability density of pr(x) = 1 / gamma(stored_alpha) * x^(stored_alpha - 1) * e^(-x).
The second member function behaves the same, except that it uses the parameters stored in par0.
Example
// std_tr1__random__gamma_distribution_operator_fn.cpp
// compile with: /EHsc
#include <random>
#include <iostream>
typedef std::ranlux64_base_01 Myeng;
typedef std::gamma_distribution<double> Mydist;
int main()
{
Myeng eng;
Mydist dist(1.5);
Mydist::input_type engval = eng();
Mydist::result_type distval = dist(eng);
distval = distval; // to quiet "unused" warnings
engval = engval;
std::cout << "alpha == " << dist.alpha() << std::endl;
dist.reset(); // discard any cached values
std::cout << "a random value == " << dist(eng) << std::endl;
std::cout << "a random value == " << dist(eng) << std::endl;
std::cout << "a random value == " << dist(eng) << std::endl;
return (0);
}
alpha == 1.5 a random value == 1.69867 a random value == 0.555659 a random value == 0.609713
Requirements
Header: <random>
Namespace: std