Periodic Function
A function is said to be periodic (or, when emphasizing the presence of a single period instead of multiple periods, singly periodic) with period
if $ f(x)=f(x+np) $ for , 2, ....
For example, the sine function $ f(x)=sin(x) $, illustrated below, is periodic with least period $ 2\pi $ (often simply called "the" period)
