Δφ: —
State: —
t: 0
About: Two Van der Pol oscillators (ẍ − μ(1−x²)ẋ + x = k(y−x)) are coupled via displacement. Each oscillator has a stable limit cycle maintained by nonlinear damping. When coupling k > 0 (in-phase tendency) or k < 0 (anti-phase), the oscillators synchronize — their phase difference Δφ locks to 0 or π. This models firefly synchronization, cardiac pacemakers, and coupled laser arrays. The phase portrait shows trajectories converging to the synchronized limit cycle.