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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) ????-2008 - 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-en.txt
function [x,uu]=gcd(p)
//Given a polynomial vector p, [pgcd,u]=gcd(p) computes the gcd
//of components and a unimodular matrix (with polynomial inverse) u,
//with minimal degree such that [p1 p2]*u=[0 ... 0 pgcd]
//!
[lhs,rhs]=argn(0)
if type(p)==8 then
if lhs==2 then [x,uu]=%i_gcd(p),else x=%i_gcd(p),end
return,
end
[m,n]=size(p)
mn=m*n
p=matrix(p,1,mn)
x=p(1);
uu=1
for l=2:mn,
[x,u]=bezout(x,p(l)),
if lhs==2 then
uu=[uu(:,1:l-2) uu(:,l-1)*u(1,[2 1])];uu(l,l-1:l)=u(2,[2 1]);
end
end,
if lhs==1 then return,end
for l=mn:-1:2
pivot=uu(l,l-1);
for k=l:mn
[r,q]=pdiv(uu(l,k),pivot)
if coeff(q)<>0 then
uu(1:l-1,k)=uu(1:l-1,k)-q*uu(1:l-1,l-1)
uu(l,k)=r;
end
end
end
endfunction
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