public member function
<random>
| (1) | explicit poisson_distribution ( double mean = 1.0 );
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| (2) | explicit poisson_distribution ( const param_type& parm ); |
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Construct Poisson distribution
Constructs a poisson_distribution object, adopting the distribution parameter specified either by mean or by object parm.
Parameters
- mean
- Expected number of events in the interval (μ).
This represents the rate at which the events being counted are observed, on average.
Its value shall be positive (μ>0).
- parm
- An object representing the distribution's parameters, obtained by a call to member function param.
param_type is a member type.
Example
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// poisson_distribution example
#include <iostream>
#include <chrono>
#include <random>
int main()
{
// construct a trivial random generator engine from a time-based seed:
unsigned seed = std::chrono::system_clock::now().time_since_epoch().count();
std::default_random_engine generator (seed);
std::poisson_distribution<int> distribution (5.2);
std::cout << "some Poisson-distributed results (mean=5.2): ";
for (int i=0; i<10; ++i)
std::cout << distribution(generator) << " ";
std::cout << std::endl;
return 0;
}
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Possible output:
some Poisson-distributed results (mean=5.2): 5 5 9 7 3 1 5 7 7 2
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