> Especially when we are talking about mains wave forms.

Yes, in our current scenario there is no reason to assume that there
would be a sudden change between samples, unless something odd happens
on the input signal (which brings me to the question: if we are
designing this to just display a 50 Hz or 60 Hz curve, why are we even
bothering sampling? We could just make a table, display it and be done
with it... When we are sampling, we would even have to make
intelligent decisions on when to restart at the left of the
screen...).

> Yes. That's why I said "usually". This of course means that there /are/
> (IMO rare) conditions where this is not the case.

Why rare? Wouldn't a proper design of sampling an analog signal (not
for display on a screen by a PICmicro, but for other purposes) use the
Nyquist=96Shannon sampling theorem, and therefore be designed such that
at the maximum frequency slightly more than two samples/period are
taken? With only two samples/period the values could be anywhere
within the range.

Greetings,
Maarten Hofman.

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