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Class template binomial_distribution

boost::random::binomial_distribution

Synopsis

// In header: <boost/random/binomial_distribution.hpp>

template<typename IntType = int, typename RealType = double> 
class binomial_distribution {
public:
  // types
  typedef IntType  result_type;
  typedef RealType input_type; 

  // member classes/structs/unions

  class param_type {
  public:
    // types
    typedef binomial_distribution distribution_type;

    // construct/copy/destruct
    explicit param_type(IntType = 1, RealType = 0.5);

    // public member functions
    IntType t() const;
    RealType p() const;

    // friend functions
    template<typename CharT, typename Traits> 
      friend std::basic_ostream< CharT, Traits > & 
      operator<<(std::basic_ostream< CharT, Traits > &, const param_type &);
    template<typename CharT, typename Traits> 
      friend std::basic_istream< CharT, Traits > & 
      operator>>(std::basic_istream< CharT, Traits > &, param_type &);
    friend bool operator==(const param_type &, const param_type &);
    friend bool operator!=(const param_type &, const param_type &);
  };

  // construct/copy/destruct
  explicit binomial_distribution(IntType = 1, RealType = 0.5);
  explicit binomial_distribution(const param_type &);

  // public member functions
  template<typename URNG> IntType operator()(URNG &) const;
  template<typename URNG> IntType operator()(URNG &, const param_type &) const;
  IntType t() const;
  RealType p() const;
  IntType min() const;
  IntType max() const;
  param_type param() const;
  void param(const param_type &);
  void reset();

  // friend functions
  template<typename CharT, typename Traits> 
    friend std::basic_ostream< CharT, Traits > & 
    operator<<(std::basic_ostream< CharT, Traits > &, 
               const binomial_distribution &);
  template<typename CharT, typename Traits> 
    friend std::basic_istream< CharT, Traits > & 
    operator>>(std::basic_istream< CharT, Traits > &, binomial_distribution &);
  friend bool operator==(const binomial_distribution &, 
                         const binomial_distribution &);
  friend bool operator!=(const binomial_distribution &, 
                         const binomial_distribution &);
};

Description

The binomial distribution is an integer valued distribution with two parameters, t and p. The values of the distribution are within the range [0,t].

The distribution function is .

The algorithm used is the BTRD algorithm described in

"The generation of binomial random variates", Wolfgang Hormann, Journal of Statistical Computation and Simulation, Volume 46, Issue 1 & 2 April 1993 , pages 101 - 110

binomial_distribution public construct/copy/destruct

  1. explicit binomial_distribution(IntType t = 1, RealType p = 0.5);

    Construct a binomial_distribution object. t and p are the parameters of the distribution.

    Requires: t >=0 && 0 <= p <= 1

  2. explicit binomial_distribution(const param_type & param);

    Construct an binomial_distribution object from the parameters.

binomial_distribution public member functions

  1. template<typename URNG> IntType operator()(URNG & urng) const;

    Returns a random variate distributed according to the binomial distribution.

  2. template<typename URNG> 
      IntType operator()(URNG & urng, const param_type & param) const;

    Returns a random variate distributed according to the binomial distribution with parameters specified by param.

  3. IntType t() const;

    Returns the t parameter of the distribution.

  4. RealType p() const;

    Returns the p parameter of the distribution.

  5. IntType min() const;

    Returns the smallest value that the distribution can produce.

  6. IntType max() const;

    Returns the largest value that the distribution can produce.

  7. param_type param() const;

    Returns the parameters of the distribution.

  8. void param(const param_type & param);

    Sets parameters of the distribution.

  9. void reset();

    Effects: Subsequent uses of the distribution do not depend on values produced by any engine prior to invoking reset.

binomial_distribution friend functions

  1. template<typename CharT, typename Traits> 
      friend std::basic_ostream< CharT, Traits > & 
      operator<<(std::basic_ostream< CharT, Traits > & os, 
                 const binomial_distribution & bd);

    Writes the parameters of the distribution to a std::ostream.

  2. template<typename CharT, typename Traits> 
      friend std::basic_istream< CharT, Traits > & 
      operator>>(std::basic_istream< CharT, Traits > & is, 
                 binomial_distribution & bd);

    Reads the parameters of the distribution from a std::istream.

  3. friend bool operator==(const binomial_distribution & lhs, 
                           const binomial_distribution & rhs);

    Returns true if the two distributions will produce the same sequence of values, given equal generators.

  4. friend bool operator!=(const binomial_distribution & lhs, 
                           const binomial_distribution & rhs);

    Returns true if the two distributions could produce different sequences of values, given equal generators.


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