std:: 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) i

The value represents the number of failures in a series of independent yes/no trials (each succeeds with probability p), before exactly 1 success occurs.

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 <iomanip>
#include <iostream>
#include <map>
#include <random>
#include <string>
 
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 [x, y] : hist)
    {
        const char c = x < 10 ? x + '0' : x - 10 + 'a';
        std::cout << c << ' ' << std::string(y / 100, '*') << '\n';
    }
}

0 *************************************************
1 *************************
2 ************
3 ******
4 **
5 *
6
7
8
9

External links