attractor/11 Hopalong (stop_motion)

Description

> a = 0.4, > b = 0.72, > c = 0.0, ``` def hopalong(a, b, c): sign = lambda x: 0 if x==0 else 1 if x>0 else -1 return lambda x, y, z: ( y - sign(x)*sqrt(abs(b*x - c)), a - x, 0 ) ```