function xc=xcovn(x,y,n)
%function xc=xcovn(x,y,n)
% cross covariance between x and y for n lags starting at lag zero
m=length(x);
%xc1=xcov(y,x,'unbiased');% note reversal of x and y
xc1=xcov(x,y,'unbiased');% note reversal of x and y(Fixed in ver 3 Signal)
xc=xc1(m:n+m-1);% zeroth lag begins at m
