Mercurial > octave
view scripts/elfun/gcd.m @ 1337:52a3f38cbfeb
[project @ 1995-08-25 02:00:18 by jwe]
author | jwe |
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date | Fri, 25 Aug 1995 02:16:01 +0000 |
parents | 611d403c7f3d |
children | 5d29638dd524 |
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# Copyright (C) 1995 John W. Eaton # # This file is part of Octave. # # Octave is free software; you can redistribute it and/or modify it # under the terms of the GNU General Public License as published by the # Free Software Foundation; either version 2, or (at your option) any # later version. # # Octave is distributed in the hope that it will be useful, but WITHOUT # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or # FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License # for more details. # # You should have received a copy of the GNU General Public License # along with Octave; see the file COPYING. If not, write to the Free # Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. function [g, v] = gcd (a, ...) # usage: gcd (a, ...) # # [g [, v]] = gcd (a) returns the greatest common divisor g of the # entries of the integer vector a, and an integer vector v such that # g = v(1) * a(k) + ... + v(k) * a(k). # # [g [, v]] = gcd (a1, ..., ak) is the same with a = [a1, ..., ak]. # Written by KH (Kurt.Hornik@ci.tuwien.ac.at) on Sep 16, 1994. if (nargin > 1) va_start; for k = 2:nargin; a = [a, (va_arg ())]; endfor endif if (round (a) != a) error ("gcd: all arguments must be integer"); endif g = abs (a(1)); v = sign (a(1)); for k = 1:(length (a) - 1) x = [g, 1, 0]; y = [(abs (a(k+1))), 0, 1]; while (y(1) > 0) r = x - y * floor (x(1) / y(1)); x = y; y = r; endwhile g = x(1); v = [x(2) * v, x(3) * (sign (a(k+1)))]; endfor endfunction