[PD] fft beginner question
matju at artengine.ca
Thu Nov 22 00:40:00 CET 2007
On Wed, 21 Nov 2007, Frank Barknecht wrote:
> Actually what comes into the rfft object are two values as well: One is
> the usual signal amplitude visible as a patch cord, and the other is:
I don't think that you can think of the time dimension as a value of what
comes into the object: I'd say that it is the index of the amplitude. Only
amplitude is transmitted: time is part of the structure of the actual
transmission, not the content.
Anyway, that idea would make the complex fft take three inputs: real,
imaginary, and time.
What [rfft~] does is assume a zero imaginary part. There's a special
version of the FFT algorithm that is only a slight optimisation because it
can assume that the imaginary input is zero. [rifft~] can assume that the
imaginary output is zero or maybe just not wanted, so it can make
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