Class template gamma_distribution

boost::random::gamma_distribution

Synopsis

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

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

  // member classes/structs/unions

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

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

    // public member functions
    RealType alpha() const;
    RealType beta() 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 gamma_distribution(const result_type & = 1.0, 
                              const result_type & = 1.0);
  explicit gamma_distribution(const param_type &);

  // public member functions
  RealType alpha() const;
  RealType beta() 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 URNG> 
    RealType operator()(URNG &, const param_type &) const;

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

Description

The gamma distribution is a continuous distribution with two parameters alpha and beta. It produces values > 0.

It has .

`gamma_distribution` public construct/copy/destruct

explicit gamma_distribution(const result_type & alpha = 1.0, 
                            const result_type & beta = 1.0);

Creates a new gamma_distribution with parameters "alpha" and "beta".

Requires: alpha > 0 && beta > 0

explicit gamma_distribution(const param_type & param);

Constructs a gamma_distribution from its parameters.

`gamma_distribution` public member functions

```
RealType alpha() const;
```
Returns the "alpha" paramter of the distribution.
```
RealType beta() const;
```
Returns the "beta" parameter of the distribution.
```
RealType min() const;
```
Returns the smallest value that the distribution can produce.
```
RealType max() const;
```
```
param_type param() const;
```
Returns the parameters of the distribution.
```
void param(const param_type & param);
```
Sets the parameters of the distribution.
```
void reset();
```
Effects: Subsequent uses of the distribution do not depend on values produced by any engine prior to invoking reset.
```
template<typename Engine> result_type operator()(Engine & eng);
```
Returns a random variate distributed according to the gamma distribution.

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

`gamma_distribution` friend functions

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

Writes a gamma_distribution to a std::ostream.

template<typename CharT, typename Traits> 
  friend std::basic_istream< CharT, Traits > & 
  operator>>(std::basic_istream< CharT, Traits > & is, 
             gamma_distribution & gd);

Reads a gamma_distribution from a std::istream.

friend bool operator==(const gamma_distribution & lhs, 
                       const gamma_distribution & rhs);

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

friend bool operator!=(const gamma_distribution & lhs, 
                       const gamma_distribution & rhs);

Returns true if the two distributions can produce different sequences of random variates, given equal generators.

Boost C++ Libraries

Class template gamma_distribution

Synopsis

Description

gamma_distribution public construct/copy/destruct

gamma_distribution public member functions

gamma_distribution friend functions

`gamma_distribution` public construct/copy/destruct

`gamma_distribution` public member functions

`gamma_distribution` friend functions