Let u(P) represents P3. The quadratic equation for the four-point rectangle, Eq.
(A), renders Eq. (3) [1]. The method that is based on the quadratic equation for
the eight-point cube, the method that renders Eq. (B), yields Eq. (4). Both of these
equations are quadratic expressions that represent a four-point rectangle with
A=1, B=27, C=343, I=729. Thus, four data in a rectangular array can sometimes
be represented by two distinct quadratic equations. All coefficients are rounded.