Sin wave

* B = 360 / Wavelength

where B is the value you put in
and Wavelength is the length of the wave you want

Thinking about it some more it should be:

B = 360 / wavelength

and wavelength is the number of pixels between cycles of the sine wave.

EDIT: Too slow

Hehe :D

One day someone will come asking about the Cosine Wave and then you can have your go :)