inverse fft: multiplicative factor missing in the definition (not in the function!)
Reported by Rémy Abergel
BUG DESCRIPTION:
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See in the documentation of the "fft" function, the formula of the inverse discrete Fourier Transform is written
x(k) = sum_{m=1}^n a(m)*exp(+(2*i*pi/n)*(m-1)*(k-1)) where n = length(x)
but a multiplicative factor (1/n) is missing, the correct formula is
x(k) = (1/n) * sum_{m=1}^n a(m)*exp(+(2*i*pi/n)*(m-1)*(k-1))
See for instance page 22 : http://www.math-info.univ-paris5.fr/~moisan/mva/mva_moisan_2012.pdf
Bests,