Reference documentation for deal.II version 9.4.1

Public Member Functions  
bool  operator() (const Point< dim, Number > &lhs, const Point< dim, Number > &rhs) const 
Comparison functor struct to compare two Points and return if one is "less" than the other one. This can be used to use Point<dim> as a key in std::map.
Comparison is done through an artificial downstream direction that tells directions apart through a factor of 1e5. Once we got the direction, we check for its value. In case the distance is exactly zero (without an epsilon), we might still have the case that two points combine in a particular way, e.g. the points (1.0, 1.0) and (1.0+1e5, 0.0). Thus, compare the points component by component in the second step. Thus, points need to have identical floating point components to be considered equal.
Definition at line 77 of file dof_tools.cc.

inline 
Comparison operator.
Return true if lhs
is considered less than rhs
.
Definition at line 85 of file dof_tools.cc.