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binomial_distribution::operator()

Returns a random value.

template<class Engine>
    result_type operator()(Engine& eng);

Engine

The type of the random engine.

eng

The random engine.

The member function uses the engine eng as a source of uniformly distributed random integral values and returns integral values with each value i occuring with probability pr(i) = comb(stored_t, i) * stored_pi * (1 - stored_p)stored_t-i, where comb(t, i) is the number of possible combinations of t objects taken i at a time.

 

// std_tr1__random__binomial_distribution_operator_fn.cpp 
// compile with: /EHsc 
#include <random> 
#include <iostream> 
 
typedef std::tr1::mt19937 Myeng; 
typedef std::tr1::binomial_distribution<int, double> Mydist; 
int main() 
    { 
    Myeng eng; 
    Mydist dist(2, 0.6); 
    Mydist::input_type engval = eng(); 
    Mydist::result_type distval = dist(eng); 
 
    distval = distval;  // to quiet "unused" warnings 
    engval = engval; 
 
    std::cout << "p == " << dist.p() << std::endl; 
    std::cout << "t == " << dist.t() << 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); 
    } 
 
p == 0.6 t == 2 a random value == 1 a random value == 0 a random value == 1

Header: <random>

Namespace: std::tr1

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