
 
returns the relative position of point t
to the sphere defined by $$p, $$q, $$r, and $$s. The order
of the points $$p, $$q, $$r, and $$s does not matter. Precondition: p, q, r and s are not coplanar.  

 
returns the position of the point t relative to the sphere passing through $$p, $$q, and $$r and whose center is in the plane defined by these three points.  

 
returns the position of the point t relative to the sphere that has $$pq as its diameter. 