DUFFING–VDP · ≤650 · DRAG PAN · PINCH ZOOM · TAP SEED
REDUCED MOTION · SETTLED ATTRACTOR
a
0.50
SPEED (dt)
0.02
FADE
0.08
PRESETS
Duffing–Van der Pol — ẋ=y, ẏ=a(1−x²)y−x³+0.3 cos z, ż=1. Phase-wrap z. Classic a=0.5. Distinct from forced-vanderpol.html / duffing.html. RK4. Gold trail, cap 650. RM = settled silhouette, no animate-on.