Ha 2016

g: 2
ε = 1 (slider from 0 to 3, step 0.1)
p: (ε * g)
r(x) = p / (1 - (ε * cos(x)))
a = CurveCartesian((r(t) * cos(t)), (r(t) * sin(t)), t, 0, (2 * π))
f: x = (-g)