26 Numerics library [numerics]

26.6 Random number generation [rand]

26.6.9 Random number distribution class templates [rand.dist] Poisson distributions [rand.dist.pois] Class template poisson_­distribution [rand.dist.pois.poisson]

A poisson_­distribution random number distribution produces integer values distributed according to the discrete probability function
The distribution parameter μ is also known as this distribution's mean.
template<class IntType = int> class poisson_distribution { public: // types using result_type = IntType; using param_type = unspecified; // constructors and reset functions poisson_distribution() : poisson_distribution(1.0) {} explicit poisson_distribution(double mean); explicit poisson_distribution(const param_type& parm); void reset(); // generating functions template<class URBG> result_type operator()(URBG& g); template<class URBG> result_type operator()(URBG& g, const param_type& parm); // property functions double mean() const; param_type param() const; void param(const param_type& parm); result_type min() const; result_type max() const; };
explicit poisson_distribution(double mean);
Preconditions: .
Remarks: mean corresponds to the parameter of the distribution.
double mean() const;
Returns: The value of the mean parameter with which the object was constructed.