[PD] algorithms for drawing filter response curves

Hans-Christoph Steiner hans at at.or.at
Tue Feb 8 04:03:56 CET 2011


On Feb 7, 2011, at 8:35 PM, Spencer Russell wrote:

> On Sun, Feb 6, 2011 at 11:15 PM, Mathieu Bouchard  
> <matju at artengine.ca> wrote:
>> On Sun, 6 Feb 2011, Spencer Russell wrote:
>>
>>> [1] gives the magnitude frequency response given the biquad
>>> coefficents, and it linked to from several places around the net. Is
>>> this the sort of thing you're looking for?
>>> [1] http://bit.ly/eFck4j
>>
>> This link got me directly to :
>>
>>  USB complete: everything you need to develop custom USB peripherals
>>  Par Jan Axelson
>>  Chapitre 12
>>  Page 364
>>
>> and nothing else. (??)
>>
>
> Whoops, I meant to send this: http://bit.ly/gUCBu4. Sorry.
>
> Here he's basically just taken the transfer function of a biquad and
> made the z = exp(j*w/Fs) as Mike suggested, followed by taking the
> magnitude and log-scaling for dB, but he's done the algebraic legwork.
> Just note that w (lower-case omega) is 2*pi*f and you should be good
> to go. He's also done some trig-substitution for more numerical
> precision.

I'm making good progress, but now am getting lost in the filter math  
meeting the pixel math.  Can someone mathy check my math?  Or even try  
it out?

https://github.com/pd-projects/filterview

.hc


----------------------------------------------------------------------------

                   ¡El pueblo unido jamás será vencido!





More information about the Pd-list mailing list