Claude Heiland-Allen wrote: > http://ccrma.stanford.edu/~jos/filters/BiQuad_Section.html > > you need to munge the biquad coefficients from the form expected by Pd's > biquad~ to the form of the difference equation at the bottom - should > just be some scaling and sign stuff. > > then you can factorize the transfer function's numerator and denominator > to get the locations of the (complex) zeroes and poles (using the > quadratic formula would do the trick) > > then feed them to [czero~] [cpole~], and an additional [*~] for the > global gain.
wow - this is a bit above my head at the moment. i can go from equations in C to pd, but only if i have the equations themselves to look at... anyway it would be great to have a pure-pd [biquad~] with signal input. it's the resonance and ability to control the Q that i'm really after, plus the ability to nice tricks (cf [hlshelf] which combines a high and low shelf filter into one [biquad~], saving cpu). [lop~] and [hip~] do the trick for simple filtering but when you want a squelchy resonant lowpass for bass triangle wav filtering, they don't cut it.. d -- damian stewart | skype: damiansnz | [EMAIL PROTECTED] frey | live art with machines | http://www.frey.co.nz _______________________________________________ [email protected] mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
