Defined in header <random> | ||
---|---|---|
template< class IntType = int > class negative_binomial_distribution; | (since C++11) |
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
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
.
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 . |
Member types
Member type | Definition |
---|---|
result_type | IntType |
param_type | the type of the parameter set, see RandomNumberDistribution . |
Member functions
constructs new distribution (public member function) | |
resets the internal state of the distribution (public member function) | |
Generation | |
operator()
| generates the next random number in the distribution (public member function) |
Characteristics | |
returns the distribution parameters (public member function) | |
gets or sets the distribution parameter object (public member function) | |
returns the minimum potentially generated value (public member function) | |
returns the maximum potentially generated value (public member function) |
Non-member functions
compares two distribution objects (function) | |
performs stream input and output on pseudo-random number distribution (function template) |
Example
#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'; } }
Output:
0 *********************** 1 ***************************** 2 ********************** 3 ************* 4 ****** 5 *** 6 * 7 8 9 10 11
External links
Weisstein, Eric W. "Negative Binomial Distribution." From MathWorld--A Wolfram Web Resource.
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