Add a useful package (from Source forge) for octave

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

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+## Copyright (C) 2006 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} {} huffmanenco (@var{sig}, @var{dict})
+##
+## Returns the Huffman encoded signal using @var{dict}. This function uses 
+## a @var{dict} built from the @code{huffmandict} and uses it to encode a
+## signal list into a huffman list. A restrictions is that a signal set must
+## strictly belong in the range @code{[1,N]} with @code{N = length(dict)}. 
+## Also @var{dict} can only be from the @code{huffmandict} routine.
+## An exmaple of the use of @code{huffmanenco} is
+##
+## @example
+## @group
+## hd = huffmandict (1:4, [0.5 0.25 0.15 0.10]);
+## huffmanenco (1:4, hd);
+##       @result{} [1 0 1 0 0 0 0 0 1]
+## @end group
+## @end example
+## @seealso{huffmandict, huffmandeco}
+## @end deftypefn
+
+function hcode = huffmanenco (sig, dict)
+  if (nargin != 2 || strcmp (class (dict),"cell") != 1)
+    print_usage;
+  elseif (max (sig) > length (dict) || min (sig) < 1)
+    error("signal has elements that are outside alphabet set. Cannot encode.");
+  endif
+  hcode = [dict{sig}];
+  return
+end
+
+%!assert(huffmanenco(1:4, huffmandict(1:4,[0.5 0.25 0.15 0.10])), [ 1   0   1   0   0   0   0   0   1 ],0)