std::negative_binomial_distribution

From cppreference.com

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 ⎞ ⎟ ⎠ \cdot p k \cdot (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.


(constructor)	constructs new distribution (public member function)

reset	resets the internal state of the distribution (public member function)
Generation

operator()	generates the next random number in the distribution (public member function)
Characteristics

k	returns the k distribution parameter (number of trial failures) (public member function)

p	returns the p distribution parameter (probability of a trial generating true) (public member function)

param	gets or sets the distribution parameter object (public member function)

min	returns the minimum potentially generated value (public member function)

max	returns the maximum potentially generated value (public member function)

[edit] Non-member functions


operator== operator!=	compares two distribution objects (function)

operator<< operator>>	performs stream input and output on pseudo-random number distribution (function)

[edit] 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

[edit] External links

Weisstein, Eric W. "Negative Binomial Distribution." From MathWorld--A Wolfram Web Resource.

Language
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)


Member type	Definition

`result_type`	IntType

`param_type`	the type of the parameter set, unspecified

std::negative_binomial_distribution

Contents

[edit] Member types

[edit] Member functions

Generation

Characteristics

[edit] Non-member functions

[edit] Example

[edit] External links