Periodic function

In mathematics a periodic function is a function that repeats itself after a while, and indefinitely. The mathematical definition of this is that $f(t)$ is periodic with period $T$ if

$f(t+T)=f(t)\ \ \forall \ t\in \mathbb {R} \ .$

Common examples of periodic functions are $\sin(\omega t)$ and $\cos(\omega t)$, which both have period $2\pi /\omega$.

A sawtooth wave is a periodic function that can be described by

f(x)=\left\{\begin{array}{cl} |x| & -1<x<1 \\ f(x+2) & \mbox{otherwise}\end{array}\right.