"rickman" wrote in message
...

Maybe I don't understand the issue. Isn't that a valid example of a
negative frequency? There are some DSP experts in comp.dsp who talk about
negative frequency often.

If you, or, indeed, anyone else has any difficulties with the subject matter
and DSP in general, then do ask me, because having worked through
what appeared as a number of anomalies (all resolved 9 years ago
when I was working as a DSP manufacturer, picoChip in Bath, UK)
I feel sure that I'm well positioned to understand the difficulties that
others might encounter in this area.