std::poisson_distribution::poisson_distribution
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                    < cpp | numeric | random | poisson distribution
                    
                                                            
                    | explicit poisson_distribution( double mean = 1.0 ); | (1) | (since C++11) | 
| explicit poisson_distribution( const param_type& params ); | (2) | (since C++11) | 
Constructs a new distribution object. The first version uses mean as the distribution parameter, the second version uses params as the distribution parameter.
[edit] Parameters
| mean | - | the μ distribution parameter (the mean of the distribution) | 
| params | - | the distribution parameter set | 
[edit] Notes
Requires that 0 < mean.