CGAL::centroid

Point_2<R>	centroid ( Point_2<R> p, Point_2<R> q, Point_2<R> r)
		compute the centroid of the points $$p, $$q, and $$r.
Point_2<R>	centroid ( Point_2<R> p, Point_2<R> q, Point_2<R> r, Point_2<R> s)
		compute the centroid of the points $$p, $$q, $$r, and $$s.
Point_3<R>	centroid ( Point_3<R> p, Point_3<R> q, Point_3<R> r)
		compute the centroid of the points $$p, $$q, and $$r.
Point_3<R>	centroid ( Point_3<R> p, Point_3<R> q, Point_3<R> r, Point_3<R> s)
		compute the centroid of the points $$p, $$q, $$r, and $$s.