negative_binomial_distribution in C++ with Examples

• Last Updated : 16 Dec, 2021

This function is defined in header randomRandom. Negative binomial distribution is Random number distribution that produces integers according to a negative binomial discrete distribution (also known as Pascal distribution), which is described by the following probability mass function. 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.
Syntax :

template( class IntType = int )
class negative_binomial_distribution

Template Parameter :
IntType : The result type generated by the generator.
Member Types
Member type & Definition

Member functions : public member function

• constructor(): Construct negative binomial distribution
• operator(): Generate random number
• reset: Reset distribution
• param: Distribution parameters
• min : Minimum value
• max : Maximum value

Distribution parameters : public member function

• k :Distribution parameter k
• p :Distribution parameter p

Non-member functions : Function Templates

• operator<< :Insert into output stream
• operator>> :Extract from input stream
• relational operators : Relational operators

Below program to illustrate the above template

CPP

 // C++ program to illustrate// negative_binomial_distribution#include using namespace std; int main(){    // number of experiments    const int exps = 10000;     // maximum number of stars to distribute    const int numberstars = 100;     // Generator generate numbers based    // upon a generator function    default_random_engine generator;     // Aman watches GOT    // At each episode, there's a 50%    // chance that john snow will die    // after how many time he'll be turned    // away before watching 4 episodes?    negative_binomial_distribution distribution(4, 0.5);     // initializing an array with size 10    int p = {};     for (int i = 0; i < exps; ++i) {        int counting = distribution(generator);        if (counting < 10)            ++p[counting];    }     cout << "Negative binomial distribution with "         << "( k = 4, p = 0.5 ) :" << endl;     // Printing the sequence stored in an array p    for (int i = 0; i < 10; ++i)        cout << i << ": " << string(p[i] * numberstars / exps, '*') << endl;     return 0;}

Output :

Negative binomial distribution with ( k = 4, p = 0.5 ) :
0: *****
1: ************
2: ****************
3: ***************
4: *************
5: **********
6: ********
7: *****
8: ***
9: **

Below program with distribution parameter of 1 and 20%
Program 2:

CPP

 // C++ program to illustrate// negative_binomial_distribution#include using namespace std; int main(){    // number of experiments    const int exps = 10000;     // maximum number of stars to distribute    const int numberstars = 100;     // Generator generate numbers based    // upon a generator function    default_random_engine generator;     // Aman watches GOT    // At each episode, there's a    // 20% chance that john snow will die    // after how many time he'll be    // turned away before watching 1 episodes?    negative_binomial_distribution distribution(1, 0.2);     // initializing an array with size 10    int p = {};     for (int i = 0; i < exps; ++i) {        int counting = distribution(generator);        if (counting < 10)            ++p[counting];    }     cout << "Negative binomial distribution with "         << "( k = 1, p = 0.2 ) :" << endl;     // Printing the sequence stored in an array p    for (int i = 0; i < 10; ++i)        cout << i << ": " << string(p[i] * numberstars / exps, '*') << endl;     return 0;}

Output :

Negative binomial distribution with ( k = 1, p = 0.2 ) :
0: *******************
1: ***************
2: ************
3: **********
4: ********
5: ******
6: *****
7: ****
8: ***
9: **

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