This applet illustrates the Fourier approximation of a periodic function by means of trigonometric polynomials.[br][br]The Fourier coefficients are computed approximately through a Discrete Fourier Transform (DFT).

The function can either be entered in the input box, or chosen from the drop-down menu.[br][br]If [math] f(x)[/math] is not a [math]2\pi[/math]-periodic function, its restriction to the interval [math][0,2\pi][/math] is used in the computations.