# Periodic Function

**Definition**: A function $f(t)$ is *periodic* if there is a number $T$ such that
$f(t+nT)=f(t)$
for every integer $n$. The number $T$ is called the *period*.

Example of periodic function:

Period of the

`\sin`

functionNotice that $f(x)=sin(x)$ has a period of $2π$. So we have write $f(x)=sin(T2πx )$, where $T$ is the period.