building fft

["otlore dolire" <otlore@hotmail.fr>]

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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