RetroSearch Browse

Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://cplusplus.com/binomial_distribution below:

class template

std::binomial_distribution

template <class IntType = int> class binomial_distribution;

Binomial distribution

Random number distribution that produces integers according to a binomial discrete distribution, which is described by the following probability mass function:

This distribution produces random integers in the range [0,t], where each value represents the number of successes in a sequence of t trials (each with a probability of success equal to p).

The distribution parameters, t and p, are set on construction.

To produce a random value following this distribution, call its member function operator().

Template parameters

IntType: An integer type. Aliased as member type result_type.
By default, this is int.

Member types The following aliases are member types of binomial_distribution:

member type definition notes result_type The first template parameter (IntType) The type of the numbers generated (defaults to int) param_type not specified The type returned by member param.

Member functions

(constructor): Construct binomial distribution (public member function)

operator(): Generate random number (public member function)

reset: Reset distribution (public member function)

param: Distribution parameters (public member function)

min: Minimum value (public member function)

max: Maximum value (public member function)

Distribution parameters

t: Upper bound of range (public member function)

p: Probability of success (public member function)

Non-member functions

operator<<: Insert into output stream (function template)

operator>>: Extract from input stream (function template)

relational operators: Relational operators (function template)

Example

// binomial_distribution
#include <iostream>
#include <random>

int main()
{
  const int nrolls = 10000; // number of experiments
  const int nstars = 100;   // maximum number of stars to distribute

  std::default_random_engine generator;
  std::binomial_distribution<int> distribution(9,0.5);

  int p[10]={};

  for (int i=0; i<nrolls; ++i) {
    int number = distribution(generator);
    ++p[number];
  }

  std::cout << "binomial_distribution (9,0.5):" << std::endl;
  for (int i=0; i<10; ++i)
    std::cout << i << ": " << std::string(p[i]*nstars/nrolls,'*') << std::endl;

  return 0;
}

Possible output:

binomial_distribution (9,0.5):
0: 
1: *
2: ******
3: ****************
4: *************************
5: ************************
6: *****************
7: *****
8: *
9: