Hastings Forced — ẋ=x(1−x)−a₁ x y/(1+b₁ x)+g cos(z), ẏ=−d₁ y+a₁ x y/(1+b₁ x), ż=w with z wrapped. Classic g=0.3. Distinct from hastings-powell.html. RK4. Gold trail, cap 650. RM = settled silhouette, no animate-on.