[PD] from poles/zeros to biquad coefficients - how to? (something like max's z-plane)
Alexandre Torres Porres
porres at gmail.com
Tue Sep 24 15:35:46 CEST 2013
so you're basically saying all i need to use is use only the real part,
my frankenstein was working and alive for several times until i tried some
bandpass coeff, let's se if i fix this now :)
2013/9/24 Funs Seelen <funsseelen at gmail.com>
> On Tue, Sep 24, 2013 at 3:08 PM, Funs Seelen <funsseelen at gmail.com> wrote:
>> On Tue, Sep 24, 2013 at 2:50 PM, Alexandre Torres Porres <
>> porres at gmail.com> wrote:
>>> one doubt emerges really soon anyway. Since they are complex (there are
>>> two coordinate numbers for each pole and zero) how do I get only one number
>>> by, for example, summing or multiplying one pole to the other? as in:
>>> *b1* = -(P0 + P1)
>>> *b2* = (P0*P1)
>> You don't, the coefficients can be complex too. However, I discovered
>> that mirroring (*) every pole and zero results in just real values without
>> imaginary part. I don't have any mathematical proof for this, but it
>> probably wouldn't be too hard to find such.
> I remembered again, it's called the complex conjugate.
>> *) adding another pole/zero for each complex one, like z=-j if you
>> already have a z=j.
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