Do not read and get scared by the following description! Just play with frequency and amplitude and enjoy;+> The triangle wave converges SOOO fast!! well, maybe the fourier series is a little bit more complicated, but basically this is just the phase shift of the integral of the square wave. It contains only odd harmonics, it is an alternating series, and its frequencies roll off to 1/f^2 (faster than square or sawtooth. It approximates a continuous waveform this time, with no discontinuities, and the worst parts of it are non-differentiable points. This is the main reason it converges so quickly. http://en.wikipedia.org/wiki/Triangle_wave