[PD] Cross correlation using FFT

[Mathieu Bouchard]

On Fri, 7 Apr 2006, Mathieu Bouchard wrote:
> 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.

D'OH, typo:

(x + ix')(y - iy') =  xy - xiy' + ix'y - ix'iy'
                   = (xy + x'y') + (x'y - xy')i

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| Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada