| Home | Libraries | People | FAQ | More

## Class template lognormal_distribution

boost::random::lognormal_distribution

## Synopsis

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

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

      // member classes/structs/unions

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

        // construct/copy/destruct
        explicit param_type(RealType = 0.0, RealType = 1.0);

        // public member functions
        RealType m() const;
        RealType s() 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 lognormal_distribution(RealType = 0.0, RealType = 1.0);
      explicit lognormal_distribution(const param_type &);

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

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

## Description

Instantiations of class template lognormal_distribution model a random distribution . Such a distribution produces random numbers with for x > 0.

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

### `lognormal_distribution` public construct/copy/destruct

1.     explicit lognormal_distribution(RealType m = 0.0, RealType s = 1.0);

   Constructs a `lognormal_distribution`. `m` and `s` are the parameters of the distribution.

2.     explicit lognormal_distribution(const param_type & param);

   Constructs a `lognormal_distribution` from its parameters.

### `lognormal_distribution` public member functions

1.     RealType m() const;

   Returns the m parameter of the distribution.

2.     RealType s() const;

   Returns the s parameter of the distribution.

3.     RealType min() const;

   Returns the smallest value that the distribution can produce.

4.     RealType max() const;

   Returns the largest value that the distribution can produce.

5.     param_type param() const;

   Returns the parameters of the distribution.

6.     void param(const param_type & param);

   Sets the parameters of the distribution.

7.     void reset();

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

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

   Returns a random variate distributed according to the lognormal distribution.

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

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

### `lognormal_distribution` friend functions

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

   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 lognormal_distribution & ld);

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

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

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

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

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