--- a +++ b/inst/@gf/isprimitive.m @@ -0,0 +1,36 @@ +## Copyright (C) 2011 David Bateman +## +## This program 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 of the License, or +## (at your option) any later version. +## +## This program 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 this program; If not, see <http://www.gnu.org/licenses/>. + +## -*- texinfo -*- +## @deftypefn {Loadable Function} {@var{y} =} isprimitive (@var{a}) +## +## Returns 1 is the polynomial represented by @var{a} is a primitive +## polynomial of GF(2). Otherwise it returns zero. +## +## @end deftypefn +## @seealso{gf,primpoly} + +function p = isprimitive (poly) + if (poly._m != 1) + error ("isprimitive: polynomials must be in GF(2)"); + endif + + x = poly._x; + if (isvector (x) && columns(x) == 1) + x = x.'; + endif + p = isprimitive (sum (x .* (2 .^ repmat (0 : columns (x) - 1, + rows(x), 1)), 2)); +endfunction