周期数据

What is a Periodic Function?

A periodic function is a function that repeats itself over regular intervals, or periods. The most common examples are trigonometric functions, such as sine, cosine, and tangent.

A periodic function will have some non-zero constant, $C$, which will allow the periodic function to relate back to the original function. This looks like: $$f(x + C) = f(x)$$ In this case, $C$ can also be considered the period of the function, since this is how often the original function will repeat itself.