update packages

[CreaPhase.git] / octave_packages / m / signal / filter2.m

diff --git a/octave_packages/m/signal/filter2.m b/octave_packages/m/signal/filter2.m
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+## Copyright (C) 2001-2012 Paul Kienzle
+##
+## This file is part of Octave.
+##
+## Octave 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.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn  {Function File} {@var{y} =} filter2 (@var{b}, @var{x})
+## @deftypefnx {Function File} {@var{y} =} filter2 (@var{b}, @var{x}, @var{shape})
+## Apply the 2-D FIR filter @var{b} to @var{x}.  If the argument
+## @var{shape} is specified, return an array of the desired shape.
+## Possible values are:
+##
+## @table @asis
+## @item 'full'
+## pad @var{x} with zeros on all sides before filtering.
+##
+## @item 'same'
+## unpadded @var{x} (default)
+##
+## @item 'valid'
+## trim @var{x} after filtering so edge effects are no included.
+## @end table
+##
+## Note this is just a variation on convolution, with the parameters
+## reversed and @var{b} rotated 180 degrees.
+## @seealso{conv2}
+## @end deftypefn
+
+## Author: Paul Kienzle <pkienzle@users.sf.net>
+## 2001-02-08
+##    * initial release
+
+function y = filter2 (b, x, shape)
+
+  if (nargin < 2 || nargin > 3)
+    print_usage ();
+  endif
+  if (nargin < 3)
+    shape = "same";
+  endif
+
+  [nr, nc] = size(b);
+  y = conv2 (x, b(nr:-1:1, nc:-1:1), shape);
+endfunction
+