function Px = bart(x,nsect)
%BART	Bartlett's method of periodogram averaging.
%----
%USAGE	Px = bart(x,nsect) 
%
%	The spectrum of a process x is estimated using Bartlett's 
%	method of periodogrm averaging.
%	
%	x     :  Input sequence
%	nsect :	 Number of subsequences to be used in the average
%
%	The Bartlett estimate is returned in Px using a linear scale.
%
%  see also PER, MPER, WELCH, and SPER
%
%---------------------------------------------------------------
% copyright 1996, by M.H. Hayes.  For use with the book 
% "Statistical Digital Signal Processing and Modeling"
% (John Wiley & Sons, 1996).
%---------------------------------------------------------------

L  = floor(length(x)/nsect);
Px = 0;
n1 = 1;
for i=1:nsect
    Px = Px + per(x(n1:n1+L-1))/nsect;
    n1 = n1 + L;
    end;