Pseudo-random number generation
Uniform random bit generators
Engines and engine adaptors
Non-deterministic generator
Uniform distributions
Bernoulli distributions
Poisson distributions
Normal distributions
Sampling distributions
Seed Sequences
C library
poisson_distribution() : poisson_distribution(1.0) {}
(1) (since C++11)
explicit poisson_distribution( double mean );
(2) (since C++11)
explicit poisson_distribution( const param_type& params );
(3) (since C++11)

Constructs a new distribution object. (2) uses mean as the distribution parameter. (3) uses params as the distribution parameter.


mean - the μ distribution parameter (the mean of the distribution)
params - the distribution parameter set


Requires that 0 < mean.

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