(Quoted from Paul's mail)
Below is another waveform generation method based on a train of sinc functions (actually
an alternating loop along a sinc between t=0 and t=period/2).
The code integrates the pulse train with a dc offset to get a sawtooth, but other shapes
can be made in the usual ways... Note that 'dc' and 'leak' may need to be adjusted for
very high or low frequencies.
I don't know how original it is (I ought to read more) but it is of usable quality,
particularly at low frequencies. There's some scope for optimisation by using a table for
sinc, or maybe a a truncated/windowed sinc?
I think it should be possible to minimise the aliasing by fine tuning 'dp' to slightly
less than 1 so the sincs join together neatly, but I haven't found the best way to do it.
Any comments gratefully received.