Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / communications-1.1.1 / egolayenc.m

diff --git a/octave_packages/communications-1.1.1/egolayenc.m b/octave_packages/communications-1.1.1/egolayenc.m
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+## Copyright (C) 2007 Muthiah Annamalai <muthiah.annamalai@uta.edu>
+##
+## 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 <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {}  egolayenc (@var{M})
+## 
+## 
+## Given @var{M}, encode M using the Extended Golay code.
+##
+## The message @var{M}, needs to be of size Nx12, for encoding.
+## We can encode several messages, into codes at once, if they 
+## are stacked in the order suggested.
+##
+## The generator G used in here is same as obtained from the
+## function egolaygen. Extended Golay code (24,12) which can correct
+## upto 3 errors.
+##
+## @example
+## @group
+## M=(rand(10,12)>0.5);
+## C=egolayenc(M)
+##
+## @end group
+## @end example
+##
+## @end deftypefn
+## @seealso{egolaygen,egolaydec}
+
+function C=egolayenc(M)
+  if ( nargin < 1 )
+    error('usage: C=egolayenc(M)');
+  elseif ( columns(M) ~= 12 )
+    error('extended golay code is (24,12), use message  of column size 12');
+  end
+
+  I=eye(12);
+  P=[1 0 0 0 1 1 1 0 1 1 0 1;
+     0 0 0 1 1 1 0 1 1 0 1 1;
+     0 0 1 1 1 0 1 1 0 1 0 1;
+     0 1 1 1 0 1 1 0 1 0 0 1;
+     1 1 1 0 1 1 0 1 0 0 0 1;
+     1 1 0 1 1 0 1 0 0 0 1 1;
+     1 0 1 1 0 1 0 0 0 1 1 1;
+     0 1 1 0 1 0 0 0 1 1 1 1;
+     1 1 0 1 0 0 0 1 1 1 0 1;
+     1 0 1 0 0 0 1 1 1 0 1 1;
+     0 1 0 0 0 1 1 1 0 1 1 1;
+     1 1 1 1 1 1 1 1 1 1 1 0;];
+  G=[P I]; %generator.
+
+  ##for rowi=1:rows(M)
+  ##   C(rowi,:)=mod(M(rowi,:)*G,2); %code.
+  ##end
+
+  C=mod(M*repmat(G,[1,rows(M)]),2);
+  C=C(:,1:24);
+
+end