Duffing Oscillator

ẍ + δẋ + αx + βx³ = γcos(ωt) — strange attractor and Poincaré sections
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Duffing: α=−1, β=1 (double-well potential V=−x²/2+x⁴/4).

Phase plane: trajectory (x, ẋ) — strange attractor has fractal structure.

Poincaré section: stroboscopic map — sample (x,ẋ) once per forcing period T=2π/ω. Periodic orbit → finite points; chaos → fractal dust.

Bifurcation diagram: steady-state x* vs γ — shows period-doubling cascade route to chaos.

Chaos preset: γ=0.30, δ=0.15, ω=1.0 — chaotic regime with visible strange attractor.