Talk:Digital biquad filter

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[edit] Coefficient notation

Some authors use b0, b1, ... for zero coeffs and a1, a2 for poles, others use a0, a1, .. for zero coeffs and b1, b2 for poles. As I know, both are used in practice. I prefer the second one, don't know if any of these is 'official'. scoofy 16:11, 26 March 2007 (UTC)

I have never seen the second version in anything "offical" (i.e. a textbook), but that's not to say that it isn't used. I think for consistency with other Wiki articles (e.g. IIR, Z-transform#Linear_constant_coefficient_difference_equation), we should stick to b for numerator, and a for denominator.

I don't think it's necessary to have a disclaimer "some authors may use a for numerator..." as was in this article previously, as this could be said about any choice of variable name in any article on Wikipedia. Oli Filth 16:19, 26 March 2007 (UTC)

Hehe, true. Digital filter uses that notation, too, so it's OK for me. One textbook which uses a0, a1... for numerator coeffs is The Scientist and Engineer's Guide to Digital Signal Processing. (Sometimes α and β is also used instead a and b.) scoofy 16:28, 26 March 2007 (UTC)