The control points P=(P1,P2,P3,...,P16) are ordered as in the bicubic 
patch setting:

P1  P2  P3  P4

P5  P6  P7  P8

P9  P10 P11 P12

P13 P14 P15 P16

This means the (u,v) coordinate is flipped to (u,1-v) compared with Jos
Stam's setting. If you don't understand this, then you probably want to
reorder the matrices V and V^-1 (Lambda is unchanged) such that the 
control points are

P13 P14 P15 P16

P9  P10 P11 P12

P5  P6  P7  P8

P1  P2  P3  P4

The diagonal of Lambda is sorted. The corresponding eigenfunctions
(or monomials in this case) are in this order:

u^0*v^0

u^0*v^1
u^1*v^0

u^0*v^2
u^1*v^1
u^2*v^0

u^0*v^3
u^1*v^2
u^2*v^1
u^3*v^0

u^1*v^3
u^2*v^2
u^3*v^1

u^2*v^3
u^3*v^2

u^3*v^3
