Surface by Roger Bagula

April 2002

y = 2 (sin(u) + 2 sin(2 u)) / (2 + cos(v + 2 pi / 3))

z = (cos(u) - 2 cos(2 u)) (2 + cos(v)) (2 + cos(v + 2 pi / 3)) / 4

-pi <= u <= pi -pi <= v <= pi

Sample C source code