Harmonics question

[Sean Costello]

At 04:13 PM 5/19/98 -0500, you wrote:

>Note that every waveform which recurs in the same shape over and over is
made up of
>the fundamental and its harmonics. Non periodic waveforms may have other non
>harmonically related frequencies in there.

I may be wrong at this, but I recall reading that if the top and bottom of a
waveform are mirror images of each other (i.e. if you lined up the positive
section of the waveform with the negative excursions of the waveform), then
the signal contains only odd harmonics. 

Man, I wish I could explain that better.  Anyone want to flesh my idea out
and/or tear it down?

Sean Costello