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## Class template extreme_value_distribution

boost::random::extreme_value_distribution

## Synopsis

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

    template<typename RealType = double>
    class extreme_value_distribution {
    public:
      // types
      typedef RealType result_type;
      typedef RealType input_type;

      // member classes/structs/unions

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

        // construct/copy/destruct
        explicit param_type(RealType = 1.0, RealType = 1.0);

        // public member functions
        RealType a() const;
        RealType b() 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 extreme_value_distribution(RealType = 1.0, RealType = 1.0);
      explicit extreme_value_distribution(const param_type &);

      // public member functions
      template<typename URNG> RealType operator()(URNG &) const;
      template<typename URNG>
        RealType operator()(URNG &, const param_type &) const;
      RealType a() const;
      RealType b() const;
      RealType min() const;
      RealType 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 extreme_value_distribution &);
      template<typename CharT, typename Traits>
        friend std::basic_istream< CharT, Traits > &
        operator>>(std::basic_istream< CharT, Traits > &,
                   const extreme_value_distribution &);
      friend bool operator==(const extreme_value_distribution &,
                             const extreme_value_distribution &);
      friend bool operator!=(const extreme_value_distribution &,
                             const extreme_value_distribution &);
    };

## Description

The extreme value distribution is a real valued distribution with two parameters a and b.

It has .

### `extreme_value_distribution` public construct/copy/destruct

1.     explicit extreme_value_distribution(RealType a = 1.0, RealType b = 1.0);

   Constructs an ``extreme_value_distribution`` from its "a" and "b" parameters.

   Requires: b > 0

2.     explicit extreme_value_distribution(const param_type & param);

   Constructs an ``extreme_value_distribution`` from its parameters.

### `extreme_value_distribution` public member functions

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

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

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

   Returns a random variate distributed accordint to the extreme value distribution with parameters specified by `param`.

3.     RealType a() const;

   Returns the "a" parameter of the distribution.

4.     RealType b() const;

   Returns the "b" parameter of the distribution.

5.     RealType min() const;

   Returns the smallest value that the distribution can produce.

6.     RealType 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 the 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.

### `extreme_value_distribution` friend functions

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

   Writes an ``extreme_value_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 extreme_value_distribution & wd);

   Reads an ``extreme_value_distribution`` from a `std::istream`.

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

   Returns true if the two instances of ``extreme_value_distribution`` will return identical sequences of values given equal generators.

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

   Returns true if the two instances of ``extreme_value_distribution`` will return different sequences of values given equal generators.