std::negative_binomial_distribution
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<tbody> </tbody> template< class IntType = int > class negative_binomial_distribution; |
( C++11) | |
i ,
:
Produces random non-negative integer values i, distributed according to discrete probability function:
- P(i|k,p) =
k + i 1
i
pk
(1 p)i
/ ( p), k .
:
The value represents the number of failures in a series of independent yes/no trials (each succeeds with probability p), before exactly k successes occur.
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(C++11)(C++11)( C++20) |
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#include <iostream>
#include <iomanip>
#include <string>
#include <map>
#include <random>
int main()
{
std::random_device rd;
std::mt19937 gen(rd());
// Pat goes door-to-door selling cookies
// At each house, there's a 75% chance that she sells one box
// how many times will she be turned away before selling 5 boxes?
std::negative_binomial_distribution<> d(5, 0.75);
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 *
7
8
9
10
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Weisstein, Eric W. "Negative Binomial Distribution." MathWorld - Wolfram Web.
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Weisstein, Eric W. "Negative Binomial Distribution." From MathWorld--A Wolfram Web Resource.