std:: negative_binomial_distribution
From cppreference.com
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Defined in header
<random>
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||
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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 ⎞
⎟
⎠ · p k · (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
(C++11)
|
IntType |
param_type
(C++11)
|
the type of the parameter set, see RandomNumberDistribution . |
Member functions
|
(C++11)
|
constructs new distribution
(public member function) |
|
(C++11)
|
resets the internal state of the distribution
(public member function) |
Generation |
|
|
(C++11)
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generates the next random number in the distribution
(public member function) |
Characteristics |
|
|
(C++11)
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returns the distribution parameters
(public member function) |
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(C++11)
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gets or sets the distribution parameter object
(public member function) |
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(C++11)
|
returns the minimum potentially generated value
(public member function) |
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(C++11)
|
returns the maximum potentially generated value
(public member function) |
Non-member functions
|
(C++11)
(C++11)
(removed in C++20)
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compares two distribution objects
(function) |
|
(C++11)
|
performs stream input and output on pseudo-random number distribution
(function template) |
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
External links
| Weisstein, Eric W. "Negative Binomial Distribution." From MathWorld — A Wolfram Web Resource. |