# [PD] from poles/zeros to biquad coefficients - how to? (something like max's z-plane)

Alexandre Torres Porres porres at gmail.com
Mon Sep 23 17:35:09 CEST 2013

```> Great that you're doing this!

thanks, here's a pic of what I have so far

https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-prn1/11212_10151872996046683_1825736206_n.jpg

> For extra inspiration you could have a look at PoZeTools

It sure does look like what I need. Thanks. But extracting what I need to
know about the math of converting from coordinates to coefficients was just
over my head :P unfortunately, sorry.

I was hoping for something simpler, like just the operations needed. If the
info is in code, I need it to more explicit. I'd really appreciate if
anyone knows how to read from this and just points it out for me so I can
put it in a patch.

I'm assuming it's rather simple math

Cheers
Alex

2013/9/23 Funs Seelen <funsseelen at gmail.com>

> Hi Alexandre,
>
> Great that you're doing this! For extra inspiration you could have a look
> at PoZeTools (http://kmt.hku.nl/~pieter/SOFT/RESP/html/PoZeTools.html).
> It's great software by Pieter Suurmond. He's the one who taught me filter
> design and he probably has some info about Z-transform on his website as
> well.
>
> Regards,
> --Funs
>
>
> On Mon, Sep 23, 2013 at 7:37 AM, Alexandre Torres Porres <porres at gmail.com
> > wrote:
>
>> Hi there. So, I've been studying a lot about filters, and I'm doing this
>> clone of max's z-plane in Pd.
>>
>> I hope anyone can help me guide where to find how to convert the values
>> of the complex poles and zeros to biquad coefficients. I really needed
>> that...
>>
>> Sorry if I missed it in Miller's book or some other obvious reference,
>> I'm just really a newbie in filter design.
>>
>> Thanks
>> Alex
>>
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>
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