[PD] biquad~ with elementary filters [was: Re: dinosaurs ...]

Charles Henry czhenry at gmail.com
Tue Sep 16 01:48:04 CEST 2008

There's two problems with your patch.
There's a sign error in one of the expr which calculates the imaginary value.
The second problem (in the same expr) was a * vs / error ( you put "/
2*$f1" instead of / 2 / $f1).  Does that make a difference?

Anyway, I jiggled with it enough to get it right.  Also, I put two
other expr that check to make sure the poles / zeros are in fact
complex rather than real.

Wait a minute.... how about just making some long expr that will sort
it out correctly and supply the zeros and poles for the real case as
well.  I'll add that too.

p.s.  I had some trouble following your expr syntax.  It makes me
wonder if there's something I don't know about expr?
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