Math/Eng: How do you find an equation from a graphical signal?

[misle]

I have a Fourier Series problem, but we were just given a graph, no equation.

The signal is periodic with a period of T
Max and min amplitudes are A & -A

I can't scan it in, so here is what I've figured out:
=A for 0 < t < T/3
=0 for T/3 < t < 2T/3
=-A for 2T/3 < t < T

then repeats. It looks like a broken square wave. If needed I could probably take a picture of it and post it.

How do I determine an equation? It should be something like A(X)(nwt) where n is number, w is omega - angular frequency and t is time.

Help!

 

[mAdD INDIAN]

isn't that heavyside function? well thats more of a pulse...which seems to be what your describing.

 

[froke]

forgot. sorry. free bump atleast?

 

[silverpig]

Mathworld should be able to tell you the exact steps in the integration. I'm too lazy to type

 

[TuxDave]

You can look at it as a summation of two pulse trains, each with a period T and an amplitude of A or -A with one of them delayed by T/3. You can then find the fourier series of a pulse train. Ya?