Diff of /inst/@gf/isprimitive.m [000000] .. [05b386] Maximize Restore

  Switch to side-by-side view

--- 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