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Quasiperiodic function 📂Functions

Quasiperiodic function

Definition 1

A function h:RRnh : \mathbb{R} \to \mathbb{R}^{n} is said to be quasiperiodic if it can be expressed in terms of a basic frequency ω1,,ωn\omega_{1} , \cdots , \omega_{n} and for each x1,,xnx_{1} , \cdots , x_{n} there exists a 2π2 \pi-periodic function HH such that the following holds hh. h(t)=H(ω1t,,ωnt) h(t) = H \left( \omega_{1} t , \cdots , \omega_{n} t \right)

Explanation

A quasiperiodic function is not literally a periodic function, but it possesses similar properties. For instance, the hh defined as follows is a quasiperiodic function. h(t)=r1cosω1t+r2sinω2t h(t) = r_{1} \cos \omega_{1} t + r_{2} \sin \omega_{2} t

On the other hand, a quasiperiodic function with infinitely many basic frequencies may also be referred to as an almost periodic function.


  1. Wiggins. (2003). Introduction to Applied Nonlinear Dynamical Systems and Chaos Second Edition(2nd Edition): p803. ↩︎