[PD] Cross correlation using FFT

Mathieu Bouchard matju at artengine.ca
Fri Apr 7 19:56:55 CEST 2006


On Fri, 7 Apr 2006, Mathieu Bouchard wrote:

> no, the case when imaginaries cancel happens only when you multiply a
> number by its own conjugate, and then it gives the square of the
> magnitude:
> (x + ix')(y - iy') =  xy + xiy' + ix'y - ix'iy'
>                    = (xy + x'y') + (xy' + x'y)i

That and the ordinary complex product should be abstractions, but Miller
doesn't seem to use abstractions much in his patches (see his FFT
tutorials...), so the two kinds of complex products are copypasted all
over the place instead. Four [*~], one [+~], one [-~], and eight more
wires than using an abstr. Brilliant.

 _ _ __ ___ _____ ________ _____________ _____________________ ...
| Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada




More information about the Pd-list mailing list