NB. Lissajous (2,3,7) knot
NB.
NB. ref: College Mathematics Journal Vol28#3 p211

fx=. 0: + 2&*
fy=. 1: + 5&*
fz=. 2.1"_ + 7&*
fn=: cos @ (fx,fy,fz) f.
KNOT=: fn makefknot (steps 0 2p1 90);11;0.2

CLEARCOLOR=: SKYBLUE
COLOR=: LIGHTGREEN
AMBIENT=: 0.1
DIFFUSE=: 0.7
SPECULAR=: 0.7
ROTXYZ=: 20 355 0

demo=: 3 : 0
knotdefault''
stdlistlight''
drawsurface makenewlist 2.5 2 2*"1 KNOT
)
