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:

• Trigonometric Function

Period of the \sin function

Notice that $f(x)=\sin (x)$ has a period of $2\pi$. So we have write $f(x)=\sin (\frac{2\pi x}{T})$, where $T$ is the period.