
 
introduces a sphere initialized to the sphere with center center,
squared radius squared_radius and orientation
orientation. Precondition: orientation $$ COPLANAR, and furthermore, squared_radius $$ 0.  

 
introduces a sphere initialized to the unique sphere which passes
through the points p, q, r and s. The
orientation of the sphere is the orientation of the point quadruple
p, q, r, s. Precondition: p, q, r, and s are not collinear.  

 
introduces a sphere initialized to the smallest sphere which passes
through the points p, q, and r. The orientation of
the sphere is o. Precondition: o is not COPLANAR.  

 
introduces a sphere initialized to the smallest sphere which passes
through the points p and q. The orientation of
the sphere is o. Precondition: o is not COPLANAR.  

 
introduces a sphere $$s initialized to the sphere with center
center, squared radius zero and orientation orientation. Precondition: orientation $$ COPLANAR. Postcondition: s.is_degenerate() = true. 