Wow, version control trouble again... the figures are indeed configured differently from the patches. I looked around and say that the patch, H11.shelving.pd, dates to August 2005 and I changed the figure between versions 08 and 09 of the book, sometime in mid 2006. So I was revising my thinking, but I left no trace of what the revision was, and didn't propagate the change back to the text in that section, nor to the H11 patch.

In one way of thinking, it's correct for the output of a shelving or peaking filter to change discontinuously when the coefficients change discontinuously, because you're in fact asking for the frequency response to change and an incoming sinusoid should get its amplitude changed immediately. I think on that reasoning the zcero~ should go afterward. And then, one should control the discontinuity by only changing the filter characteristics continuously.

At one point I spent some time trying to get the butterworth filters to work smoothly with changing coefficients. I tried with zeros before the poles and after, both as a batch and in pairs, and never got satisfactory results.

I've stuck this in my small but growing errata file - thanks for flagging it!

Miller

On Mon, Nov 17, 2008 at 03:43:20PM +0100, Frank Barknecht wrote:

Hallo,

hm, I'm a bit confused how to place elementary filters: In the book, Miller writes that the r/czero should be placed before the poles and the screenshots also show this: http://crca.ucsd.edu/~msp/techniques/latest/book-html/node160.html

However the example patches (H11 ff.) and the butterworth abstractions that come with Pd have it the other way around and follow the alphabetic order with *z*ero last!

Ciao

Frank Barknecht Do You RjDj.me? _ ______footils.org__

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