CGAL::circumcenter

Point_2<R>	circumcenter ( Point_2<R> p, Point_2<R> q, Point_2<R> r)
		compute the center of the circle passing through the points $$p, $$q, and $$r. Precondition: $$p, $$q, and $$r are not collinear.
Point_3<R>	circumcenter ( Point_3<R> p, Point_3<R> q, Point_3<R> r)
		compute the center of the circle passing through the points $$p, $$q, and $$r. Precondition: $$p, $$q, and $$r are not collinear.
Point_3<R>	circumcenter ( Point_3<R> p, Point_3<R> q, Point_3<R> r, Point_3<R> s)
		compute the center of the sphere passing through the points $$p, $$q, $$r, and $$s. Precondition: $$p, $$q, $$r, and $$s are not coplanar.