update packages

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

diff --git a/octave_packages/m/signal/hanning.m b/octave_packages/m/signal/hanning.m
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+## Copyright (C) 1995-2012 Andreas Weingessel
+##
+## 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} {} hanning (@var{m})
+## Return the filter coefficients of a Hanning window of length @var{m}.
+##
+## For a definition of this window type, see e.g., A. V. Oppenheim &
+## R. W. Schafer, @cite{Discrete-Time Signal Processing}.
+## @end deftypefn
+
+## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at>
+## Description: Coefficients of the Hanning window
+
+function c = hanning (m)
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  if (! (isscalar (m) && (m == fix (m)) && (m > 0)))
+    error ("hanning: M has to be an integer > 0");
+  endif
+
+  if (m == 1)
+    c = 1;
+  else
+    m = m - 1;
+    c = 0.5 - 0.5 * cos (2 * pi * (0 : m)' / m);
+  endif
+
+endfunction
+
+%!assert (hanning (1), 1);
+%!assert (hanning (2), zeros(2,1));
+%!assert (hanning (16), fliplr (hanning (16)));
+%!assert (hanning (15), fliplr (hanning (15)));
+%!test
+%! N = 15;
+%! A = hanning (N);
+%! assert (A (ceil (N/2)), 1);
+
+%!error hanning ();
+%!error hanning (0.5);
+%!error hanning (-1);
+%!error hanning (ones(1,4));