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@pizzapal @pkw
I guess you're doomed to be a polylang. Sorry to hear about the virus!
Discrete fourier transforms are defined by
(defun naieve-dft (l &key (sgn -1) &aux (len (length l)))
"consing naieve dft of list. Computes all twiddle factors. :sgn +1 for inverse."
(loop
:for k :below len
:collecting
(loop :for n :below len
:for w := (twiddle k n len :sgn sgn)
:sum
(* (nth n l) w))))
twiddles=(exp (* #C(0 1) sgn pi 2 k n (/ len)))
But this turns out to be overdefined