d^{2}x ⁄ dt^{2} + k dx ⁄ dt + x^{3} = B cos t

x = y = dx ⁄ dt =

h = 2π/

Plot at t = nh 2nπ (n = 0, 1, 2, …)

k = 0.1, B = 12 (x = 3, y = 0) : Japanese attractor k = 0.05, B = 7.5 : Ueda's chaotic attractor