Function closest_intersection_point 

pub fn closest_intersection_point(
    point: &Vector3d,
    centroid: &Vector3d,
) -> Vector3d

Return the closer intersection point to the centroid of the Arcs.

• point a great-circle intersection point.
• centroid the centroid of the Arcs mid points.

returns the antipodal point if it is closer to the centroid, otherwise returns the point.