Fri Jan 14 15:44:14 EST 2011

Factored FIR

Q: Are there any FIR filter design algorithms that explicitly rely on
   the equation to be in factored-out form, i.e. as a product of 2nd
   order sections?

I suppose this introduces the problem of having to specify whether FIR
zeros are complex or not.  I seem to remember them mostly being
complex, exept for odd orders where there would be one zero.

Q: Is there a reason why FIR filters have "mostly complex" zeros?  

Is this equivalent to asking why their inverses the IIR all-pole
filters have "mostly complex" poles?  (Because that gives more