Editing Periodic function (section)

===Complex number examples===
Using [[complex analysis|complex variables]] we have the common period function:

:<math>e^{ikx} = \cos kx + i\,\sin kx.</math>

Since the cosine and sine functions are both periodic with period <math>2\pi</math>, the complex exponential is made up of cosine and sine waves. This means that [[Euler's formula]] (above) has the property such that if <math>L</math> is the period of the function, then

:<math>L = \frac{2\pi}{k}.</math>

====Double-periodic functions====
A function whose domain is the [[complex number]]s can have two incommensurate periods without being constant. The [[elliptic function]]s are such functions. ("Incommensurate" in this context means not real multiples of each other.)