% PLOTACF.M Plots normalized autocorrelation function
%
% [acf]=plotacf(x,errlim,len,print_code)
%
%  acf = autocorrelation values
%  x = time series data
%  errlim > 0; error limit = 2/sqrt(data_len)
%  len = length of acf that need to be plotted
%  NOTE: if len=0 then len=data_length/2;
%  print_code = 0 ==> does not plot OR ELSE plots

function [x]=plotacf(y,errlim,len,code)

x=xcov(y); l=length(y); x=x/x(l);
r=l:2*(l-1); lim=2/sqrt(l); rl=1:length(r) ; 
N=length(rl); x=x(r); 
if len>0 & len<N, rl=1:len; x=x(rl); N=len; end;
axis([0 length(rl) min(min(x),-lim-0.1) 1.1])
axis off, axes('FontSize',18);
if(code > 0 )
  if(errlim > 0 )
    rl=rl-1;
    plot(rl,x,rl,x,'o' , rl,lim*ones(N,1),'--', ...
         rl,-lim*ones(N,1),'--')
    grid
  else
    plot(rl,x )
  end
end;
label(' ',18,'Lag','ACF',18)