std::negative_binomial_distribution
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negative_binomial_distribution
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std::negative_binomial_distribution
Member functions
Generation
Characteristics
Non-member functions
(C++11)(C++11)(until C++20)
(C++11)(C++11)
Defined in header
<random>
template< class IntType = int >
class negative_binomial_distribution;
(since C++11)
class negative_binomial_distribution;
Produces random non-negative integer values i, distributed according to discrete probability function:
- \(P(i|k, p) = \binom{k + i - 1}{i} \cdot p^k \cdot (1 - p)^i\)P(i|k,p) =⎛
⎜
⎝k + i − 1
i⎞
⎟
⎠ · pk
· (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 k successes occur.
std::negative_binomial_distribution satisfies RandomNumberDistribution.
Contents
[edit] Template parameters
IntType
-
The result type generated by the generator. The effect is undefined if this is not one of short, int, long, long long, unsigned short, unsigned int, unsigned long, or unsigned long long.
[edit] Member types
Member type
Definition
result_type (C++11)
IntType
[edit] Member functions
Generation
Characteristics
[edit] Non-member functions
(C++11)
(function template) [edit]
[edit] Example
Run this code
#include <iomanip> #include <iostream> #include <map> #include <random> #include <string> 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 [x, y] : hist) std::cout << std::hex << x << ' ' << std::string (y / 100, '*') << '\n'; }
Possible output:
0 *********************** 1 ***************************** 2 ********************** 3 ************* 4 ****** 5 *** 6 * 7 8 9 a b
[edit] External links
Weisstein, Eric W. "Negative Binomial Distribution." From MathWorld — A Wolfram Web Resource.