Chaos Lab

Discrete map · 1D · dim 1

Circle map

Arnold's standard form for the iterates of a circle homeomorphism with a sinusoidal nonlinearity. Famous for Arnold tongues (resonance regions) and devil-staircase rotation number.

Devil's staircase: rotation number ρ vs Ω at K = 1. Plateaux are Arnold tongues (mode locking).

Equations

θ_{n+1} = θ_n + Ω − (K/2π) sin(2π θ_n) mod 1

At a glance

ParametersΩ ∈ [0, 1], K ≥ 0
Chaotic forK > 1 (above the critical curve, tongues overlap)
HistoryArnold (1965); central to Kolmogorov-Arnold-Moser (KAM) studies.

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See also

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