%Taken directly from LPC Vocoder GUI ver. 1.0
%@http://www.mathworks.com/matlabcentral/fileexchange/20331
%Function that outputs autocorrelation of a vector
function Rn=autocorr(k,data)
N=size(data,1);
sn=data; %s_n(m)
sm=circshift(data,[-k,0]); %s_n(m-k)
if k>0
    sm(N-k+1:N)=zeros(k,1); %pad end of shifted vector with zeros
end
Rn=dot(sn,sm); %R_n(k)