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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_V2.1-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]
//!
if type(p)<>1 & type(p)<>2 & type(p)<>8 then
error(msprintf(_("%s: Wrong type for argument #%d: Integer array or Polynomial expected.\n"), "gcd", 1));
end
if type(p)==1 then
if floor(p)<>p then
error(msprintf(_("%s: Wrong type for argument #%d: Integer array or Polynomial expected.\n"), "gcd", 1));
else
p = iconvert(p,4);
end
end
[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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