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## Class template geometric_distribution

boost::random::geometric_distribution

## Synopsis

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

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

      // member classes/structs/unions

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

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

        // public member functions
        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 > &, const param_type &);
        friend bool operator==(const param_type &, const param_type &);
        friend bool operator!=(const param_type &, const param_type &);
      };

      // construct/copy/destruct
      explicit geometric_distribution(const RealType & = 0.5);
      explicit geometric_distribution(const param_type &);

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

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

## Description

An instantiation of the class template `geometric_distribution` models a random distribution . The distribution produces positive integers which are the number of bernoulli trials with probability `p` required to get one that fails.

For the geometric distribution, .

| Warning
This distribution has been updated to match the C++ standard. Its behavior has changed from the original boost::geometric_distribution. A backwards compatible wrapper is provided in namespace boost.

### `geometric_distribution` public construct/copy/destruct

1.     explicit geometric_distribution(const RealType & p = 0.5);

   Contructs a new `geometric_distribution` with the paramter `p`.

   Requires: 0 < p < 1

2.     explicit geometric_distribution(const param_type & param);

   Constructs a new `geometric_distribution` from its parameters.

### `geometric_distribution` public member functions

1.     RealType p() const;

   Returns: the distribution parameter `p`

2.     IntType min() const;

   Returns the smallest value that the distribution can produce.

3.     IntType max() const;

   Returns the largest value that the distribution can produce.

4.     param_type param() const;

   Returns the parameters of the distribution.

5.     void param(const param_type & param);

   Sets the parameters of the distribution.

6.     void reset();

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

7.     template<typename Engine> result_type operator()(Engine & eng) const;

   Returns a random variate distributed according to the `geometric_distribution`.

8.     template<typename Engine>
         result_type operator()(Engine & eng, const param_type & param) const;

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

### `geometric_distribution` friend functions

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

   Writes 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,
                    const geometric_distribution & gd);

   Reads the distribution from a `std::istream`.

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

   Returns true if the two distributions will produce identical sequences of values given equal generators.

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

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