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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) INRIA - 1988 - C. Bunks
// Copyright (C) INRIA - 1991 - C. Bunks
//
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution. The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2.1-en.txt
function [sm,fr]=mese(x,npts);
//<sm,fr]=mese(x [,npts]);
//Calculate the maximum entropy spectral estimate of x
// x :Input sampled data sequence
// npts :Optional parameter giving number of points of fr and sm
// (default is 256)
// sm :Samples of spectral estimate on the frequency grid fr
// fr :npts equally spaced frequency samples in [0,.5)
//!
//default evaluation
[rhs,lhs]=argn(0);
if lhs==1 then,
npts=256;
end,
//estimate autocorrelation function of x
Nx=length(x);
r=convol(x,x(Nx:-1:1))
r=r(Nx:-1:1)/Nx;
//get solution to the Yule-Walker equations
[ar,sigma2,rc]=lev(r);
//compute spectrum
ak=[1;ar];
[sf,fr]=frmag(ak,npts);
sm=sigma2*ones(sf)./(sf.*conj(sf));
endfunction
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