
 
Compares the Cartesian coordinates of points p and q lexicographically in $$xyz order: first $$xcoordinates are compared, if they are equal, $$ycoordinates are compared, and if both $$x and $$y coordinate are equal, $$zcoordinates are compared. 
CGAL::compare_xy
CGAL::compare_x
CGAL::compare_x_at_y
CGAL::compare_y
CGAL::compare_yx
CGAL::compare_y_at_x
CGAL::compare_z