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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) ????-2008 - INRIA - Francois DELBECQUE
//
// 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 [Ns,d]=coffg(Fs)
// [Ns,d]=coffg(Fs) computes Fs^-1 where Fs is a polynomial
// or rational matrix by co-factors method.
// d = common denominator; Ns = numerator (matrix polynomial)
// Fs inverse = Ns/d.
// (Be patient...results are generally reliable)
// See also det, detr, invr, penlaur, glever, leverrier
//!
//
if or(typeof(Fs)==["polynomial" "constant"]) then
[n,np]=size(Fs);
if n<>np then
error(msprintf(gettext("%s: Wrong size for input argument #%d: A square matrix expected.\n"),"coffg",1))
end
d=det(Fs) // common denominator
n1=n;
for kk=1:n1,for l=1:n1,
signe=(-1)^(kk+l);
col=[1:kk-1,kk+1:n1];row=[1:l-1,l+1:n1];
Ns(kk,l)=-signe*det(Fs(row,col))
end;end
Ns=-Ns;
elseif typeof(Fs)=="rational" then
[n,np]=size(Fs);
if n<>np then
error(msprintf(gettext("%s: Wrong size for input argument #%d: A square matrix expected.\n"),"coffg",1))
end
d=det(Fs) // common denominator
n1=n;
for kk=1:n1,for l=1:n1,
signe=(-1)^(kk+l);
col=[1:kk-1,kk+1:n1];row=[1:l-1,l+1:n1];
Ns(kk,l)=-signe*det(Fs(row,col))
end;end
Ns=-Ns;
else
error(msprintf(gettext("%s: Wrong type for input argument #%d: A floating point number or polynomial or rational fraction array expected.\n"),"detr",1))
end
endfunction
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