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Output of Fourier Transforms of Complex Data
The output of fftc1 is arranged as follows. The first half of the
output array represents the positive frequencies
. The index then wraps around to and begins ascending
from there. (Remember that and are the same
point.) Bearing in mind that the array contains alternating real and
imaginary components, the input and output arrays look like:

(7) 

(8) 
Remember that and are actually the same array because the
output data are written over the original input array. The output of
fftcn is arranged analogously to fftc1. Each dimension goes from
to and then from up to and the whole array
alternates between real and imaginary parts.
To do an inverse Fourier transform simply arrange the values as
described here. If the array was produced as output of the
FFTEASY routines then it is already arranged correctly to be put back
in for the inverse Fourier transform.
Next: Output of Fourier Transforms
Up: Storage: What Goes Where
Previous: Fourier Transform Definitions and
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