The model is one piece of blade in an impeller, which is a cubic
B-spline with C2 continuity and consisting of 394 cubic curve
segments.

A cubic polynomial
   x = a3 x^3 + a2 x^2 + a1 x + a0
   y = b3 y^3 + b2 y^2 + b1 y + b0
   z = c3 z^3 + c2 z^2 + c1 z + c0
is represented by
   [[a0, a1, a2, a3], [b0, b1, b2, b3], [c0, c1, c2, c3]]


A cubic spline consisting of n segments defined on [0,1] is
represented by
   [c1,c2,...,cn, [u1=0,u2,...,u_n,u_{n+1}=1]]
where each ci is a cubic polynomial defined on [u_i,u_{i+1]].

A model consisting of m cubic splines if represented by
   [s1,s2,...,sm]

2011.5