std::geometric_distribution

template< class IntType = int >
class geometric_distribution;

Produces random non-negative integer values i, distributed according to discrete probability function: \(P(i|p) = p \cdot (1-p)^i\)P(i|p) = p · (1 − p).

The value represents the number of yes/no trials (each succeeding with probability p) which are necessary to obtain a single success.

std::geometric_distribution<>(p) is exactly equivalent to std::negative_binomial_distribution<>(1, p). It is also the discrete counterpart of std::exponential_distribution.

std::geometric_distribution satisfies RandomNumberDistribution.

Template parameters

Member types

Member functions

Non-member functions

Example

#include <iostream>
#include <iomanip>
#include <string>
#include <map>
#include <random>
int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());
 
    std::geometric_distribution<> d; // same as std::negative_binomial_distribution<> d(1, 0.5);
 
    std::map<int, int> hist;
    for(int n=0; n<10000; ++n) {
        ++hist[d(gen)];
    }
    for(auto p : hist) {
        std::cout << p.first <<
                ' ' << std::string(p.second/100, '*') << '\n';
    }
}

0 *************************************************
1 *************************
2 ************
3 ******
4 **
5 *
6 
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External links

Weisstein, Eric W. "Geometric Distribution." From MathWorld--A Wolfram Web Resource.