## [f62e8c]: inst / cosets.m Maximize Restore History

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57``` ```## Copyright (C) 2002 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 3 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 . ## -*- texinfo -*- ## @deftypefn {Function File} {} cosets (@var{m}, @var{prim}) ## ## Finds the elements of GF(2^@var{m}) with primitive polynomial @var{prim}, ## that share the same minimum polynomial. Returns a cell array of the ## partitioning of GF(2^@var{m}). ## @end deftypefn function c = cosets (m, prim) if (nargin == 1) prim = 0; ## This flags to use default primitive elseif (nargin != 2) print_usage (); endif n = 2^m-1; found = zeros (1, n); c{1} = gf (1, m, prim); found(1) = 1; nc = 2; f = log (gf (1:n, m, prim)); while (!all (found)) t = find (!found); idx = f(t(find (f(t) == min (f(t).x)))).x; set = idx; r = rem (idx*2, n); while (r > idx) set = [set, r]; r = rem (r*2, n); endwhile c{nc} = gf (sort (exp (gf (set, m, prim)).x), m, prim); found(c{nc}.x) = ones (1, length (c{nc})); nc = nc + 1; endwhile endfunction %% Test input validation %!error cosets () %!error cosets (1, 2, 3) ```