NB.  some definitions for Bezier curves.

shape =: $
floor =: <.
mp =: (+/) . *
table =: /

n =: 20

t =: ((%n) * i. 1+n) ^/ 3 2 1 0

m =: 4 4 shape _1 3 _3 1 3 _6 3 0 _3 3 0 0 1 0 0 0

curve =: 4 2 shape 166 70 92 55 73 141 132 179

bc =: floor t mp m mp curve