text: /*!
  \ingroup PkgBarycentric_coordinates_2Concepts
  \cgalConcept
  
  Requirements of the template parameter `Traits` for all the classes with two-dimensional barycentric coordinates from the namespace `CGAL::Barycentric_coordinates`. 
  
  \cgalHasModel All models of `Kernel`
  
  */
  
  class BarycentricTraits_2 {
  
  public:
  
  /// \name Types 
  /// @{
  
  /*!
  	A model of `FieldNumberType`.
  */ 
  typedef unspecified_type FT;
  
  /// @}
  
  /// \name Two-dimensional Geometric Objects
  /// @{
  
  /*!
  	A model of `Kernel::Point_2`.
  */ 
  typedef unspecified_type Point_2; 
  
  /*!
  	A model of `Kernel::Vector_2`.
  */ 
  typedef unspecified_type Vector_2; 
  
  /// @} 
  
  /// \name Two-dimensional Constructions
  /// @{
  
  /*!
  	A model of this concept must provide an FT operator(const Point_2 &p, const Point_2 &q, const Point_2 &r) 
  	that returns the signed area of the triangle defined by the points p, q, and r.
  */ 
  typedef unspecified_type Compute_area_2; 
  
  /*!
      A model of this concept must provide an FT operator(const Point_2 &p, const Point_2 &q)
      that returns the squared Euclidean distance between the points p and q.
  */ 
  typedef unspecified_type Compute_squared_distance_2; 
  
  /*!
      A model of this concept must provide an FT operator(const Vector_2 &p)
      that returns the squared length of the vector p.
  */ 
  typedef unspecified_type Compute_squared_length_2;
  
  /*!
      A model of this concept must provide an FT operator(const Vector_2 &p, const Vector_2 &q)
      that returns the scalar product between the vectors p and q.
  */
  typedef unspecified_type Compute_scalar_product_2;
  
  /// @}
  
  /// \name Two-dimensional Generalized Predicates
  /// @{
  
  /*!
  	A model of this concept must provide a bool operator(const Point_2 &p, const Point_2 &q)
  	that returns true if p = q and false otherwise.
  */ 
  typedef unspecified_type Equal_2; 
  
  /*!
  	A model of this concept must provide a bool operator(const Point_2 &p, const Point_2 &q, const Point_2 &r)
  	that returns true if the points p, q, and r are collinear and false otherwise.
  */ 
  typedef unspecified_type Collinear_2; 
  
  /*!
  	A model of this concept must provide a bool operator(const Point_2 &p, const Point_2 &q, const Point_2 &r)
  	that returns true if the point q lies between the points p and r and all three points are collinear.
  */ 
  typedef unspecified_type Collinear_are_ordered_along_line_2; 
  
  /// @} 
  
  }; /* end BarycentricTraits_2 */
  