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| Date: | -- (:) |
| From: | otlore dolire <otlore@h...> |
| Subject: | building fft |
I have a problem with a basic fft function i'm tryin to build. I think it's
right, yet it raises conflicts, as if it didn't recognize the "end" at the
end of it. Can you please tell me if someone sees something wrong? thx in
advance
let rec fft N w y =
let Y = make_vect N {Re = 0. ; Im = 0.}
in
if N = 1 then begin Y.(0) <- y.(0) end
else
begin let m = div_int N 2;
let l1 = make_vect m {Re = 0. ; Im = 0. }
and l2 = make_vect m {Re = 0. ; Im = 0. }
in for k = 0 to m - 1 do
l1.(k) <- y.(2*k);
l2.(k) <- y.(2*k + 1)
done;
let L1 = make_vect m {Re = 0. ; Im = 0. }
and L2 = make_vect m {Re = 0. ; Im = 0. }
in
for i = 0 to m - 1 do
L1.(i) <- (fft m (prod w w) l1).(i);
L2.(i) <- (fft m (prod w w) l2).(i)
done;
let wk = ref {Re = 1. ; Im = 0. }
and P = ref {Re = 0. ; Im = 0. }
and I = ref {Re = 0. ; Im = 0. }
in for k=0 to m - 1 do
P := L1.(k);
I := prod !wk L2.(k);
Y.(k) <- prod (add !P !I) {Re = 0.5 ; Im = 0. };
Y.(k + m) <- prod (sous !P !I) {Re = 0.5 ; Im = 0. };
wk := prod !wk w
done
end;
Y;;
PS: i defined the type cplx by type cplx = {Re : float ; Im : float}, prod,
add and sous are respectively product, addition and substraction of cplx
numbers
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