Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / communications-1.1.1 / @galois / deconv.m

diff --git a/octave_packages/communications-1.1.1/@galois/deconv.m b/octave_packages/communications-1.1.1/@galois/deconv.m
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+++ b/octave_packages/communications-1.1.1/@galois/deconv.m
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+## 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 <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} deconv (@var{y}, @var{a})
+## Deconvolve two Galois vectors.
+##
+## @code{[b, r] = deconv (y, a)} solves for @var{b} and @var{r} such that
+## @code{y = conv (a, b) + r}.
+##
+## If @var{y} and @var{a} are polynomial coefficient vectors, @var{b} will
+## contain the coefficients of the polynomial quotient and @var{r} will be
+## a remander polynomial of lowest order.
+## @end deftypefn
+## @seealso{conv}
+
+function [b, r] = deconv (y, a)
+
+
+  if (nargin != 2)
+    usage ("deconv(a, b)");
+  endif
+
+  if (!isgalois (y) && !isgalois (a))
+    error("deconv: at least one argument must be a galois variable");
+  elseif (!isgalois (y))
+    y = gf(y, a.m, a.prim_poly);
+  elseif (!isgalois (a))
+    a = gf(a, y.m, y.prim_poly);
+  elseif (a.m != y.m && a.prim_poly != y.prim_poly)
+    error("deconv: both vectors must be in the same galois field");
+  endif
+  
+  if (min(size(a)) > 1 || min(size(y)) > 1)
+    error("deconv: both arguments must be vectors");
+  endif
+
+  la = length (a);
+  ly = length (y);
+
+  lb = ly - la + 1;
+
+  ## Ensure that both vectors are row vectors.
+  if (rows (a) > 1)
+    a = reshape (a, 1, la);
+  endif
+  if (rows (y) > 1)
+    y = reshape (y, 1, ly);
+  endif
+  
+  if (ly > la)
+    b = filter (y, a, [1, (zeros (1, ly - la))]);
+  elseif (ly == la)
+    b = filter (y, a, 1);
+  else
+    b = gf(0, y.m, y.prim_poly);
+  endif
+
+  lc = la + length (b) - 1;
+  if (ly == lc)
+    r = y - conv (a, b);
+  else
+    ## Can't concatenate galois variables like this yet
+    ## r = [(zeros (1, lc - ly)), y] - conv (a, b);
+    r = gf([(zeros (1, lc - ly)), y], y.m, y.prim_poly) - conv (a, b);
+  endif
+
+endfunction