Class template chi_squared

Class template chi_squared_distribution

boost::random::chi_squared_distribution

Synopsis

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

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

  // member classes/structs/unions

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

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

    // public member functions
    RealType n() 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 chi_squared_distribution(RealType = 1);
  explicit chi_squared_distribution(const param_type &);

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

Description

The chi squared distribution is a real valued distribution with one parameter, n. The distribution produces values > 0.

The distribution function is .

`chi_squared_distribution` public construct/copy/destruct

```
explicit chi_squared_distribution(RealType n = 1);
```
Construct a chi_squared_distribution object. n is the parameter of the distribution.

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

explicit chi_squared_distribution(const param_type & param);

Construct an chi_squared_distribution object from the parameters.

`chi_squared_distribution` public member functions

```
template<typename URNG> RealType operator()(URNG & urng);
```
Returns a random variate distributed according to the chi squared distribution.
```
template<typename URNG> 
  RealType operator()(URNG & urng, const param_type & param) const;
```
Returns a random variate distributed according to the chi squared distribution with parameters specified by param.
```
RealType n() const;
```
Returns the n parameter of the distribution.
```
RealType min() const;
```
Returns the smallest value that the distribution can produce.
```
RealType max() const;
```
Returns the largest value that the distribution can produce.
```
param_type param() const;
```
Returns the parameters of the distribution.
```
void param(const param_type & param);
```
Sets 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.

`chi_squared_distribution` friend functions

template<typename CharT, typename Traits> 
  friend std::basic_ostream< CharT, Traits > & 
  operator<<(std::basic_ostream< CharT, Traits > & os, 
             const chi_squared_distribution & c2d);

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

template<typename CharT, typename Traits> 
  friend std::basic_istream< CharT, Traits > & 
  operator>>(std::basic_istream< CharT, Traits > & is, 
             chi_squared_distribution & c2d);

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

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

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

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

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