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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) INRIA -
//
// 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 [gm]=cfspec(g)
//[gm]=cfspec(g) computes a co-spectral factorization:
// g = gm*gtild(gm)
//with stable gm and gm^-1 ( gm^-1 = invsyslin(gm) ).
//-- g: syslin list defining the linear system g
//-- gm:
//Assumptions:
//- g is invertible ( inv(D) exists ),
//- g and g^1 (invsyslin(g)) have no poles on the imaginary axis.
//- gtild(g) = g.
// (poles and zeros of g are symmetric wrt imaginary axis))
//- g(+oo) = D is positive definite.
//!
if type(g)==1 then gm=chol(g),return,end,
gm=fspec(g'),
gm=gm'
endfunction
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