% correl(x,y,N)

function rxy = correlt(x,y,S)

L = lge(x);
N = L-S;

if (N == 0)
  error('N = 0 !');
end;

for s=1:S,
rxy(s)=sum(x(S-s+1:L-s+1).*y(S:L))^2/(sum(x(S-s+1:L-s+1).^2)*sum(y(S:L).^2));
%rxy(s)=abs(sum(x(S-s+1:L-s+1).*y(S:L)))/(sum(abs(x(S-s+1:L-s+1).*y(S:L)))+0.0001);
end;