function [L,R]=pitchcor(x,lmin,lmax,thr)
%
% Syntax: [L,R]=pitchcor(x,lmin,lmax,thr)
%
% Computes pitch using autocorrelation method.
% x is the signal frame
% lmin is minimal lag in samples
% lmax is maximal lag in samples
% thr  is a relative threshold Rmax/R0 >= thr => voiced
%                              Rmax/R0 < thr  => unvoiced
% L is  lag in samples for voiced, 0 for unvoiced frame
% R (facultative) is the vector of autocorrelation coefficients

N=length(x);

aaa=xcorr(x);
R=aaa(N:(2*N-1));

[Rmax,ii]=max(R(lmin+1:lmax+1));

if Rmax/R(1) >= thr,
  L=ii+lmin-1;
else
  L=0;
end