#http://www-gap.dcs.st-and.ac.uk/~history/Curves/Double.html

vertices = D1:360 D2:100

u = from 0 to (PI) D1
v = from (-PI/2) to (PI/2) D2

r = 4*cos(u)*sin(u)*sin(u)

x = r*sin(u)
y = r*cos(u)

a = 10
b = 2

x = x*a*cos(v)
y = y*a*cos(v)
z = b*sin(v)
