File talk:Periodic identity function.gif
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I think this graph is incorrect. Assuming all the harmonics are sine waves with phase 0 the sawtooth should not slope upwards from zero. In fact it should go from minimum to maximum value at zero, and descend.
If this assumption isn't correct, why illustrate something other than what seems to be the simplest case (phase 0 sine waves) and why not mention it?
Finally, even considering that the user possibly wanted to illustrate some other collection of phases, the fundamental is shown as a phase 0 sine, which is absolutely not a component of this sawtooth.
Frank