20 Feb
2012
20 Feb
'12
12:12 a.m.
Le 2012-02-19 à 17:48:00, Mike Moser-Booth a écrit :
On Sun, Feb 19, 2012 at 4:54 PM, Mathieu Bouchard matju@artengine.ca wrote:
Why would you change the signs of a and b but not c ? (Was I giving the formula relative to ax²+bx+c=0 or did I assume ax²+bx=c by accident ?)
I think it has to do with where c is in the difference equation: c*y[n] = g*x[n] + a*y[n-1] + b*y[n-2]
This equation uses a for the middle term (y[n-1]) ? Weird.
I'd expect b to go with y[n-1], whereas a and c would go with either y[n] or y[n-2]...
BTW, the equations I used are things that I reconstituted from the source code of [biquad~] in pd/src/d_filter.c. They don't come from manuals.
| Mathieu BOUCHARD ----- téléphone : +1.514.383.3801 ----- Montréal, QC