update packages

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

diff --git a/octave_packages/m/signal/hamming.m b/octave_packages/m/signal/hamming.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} {} hamming (@var{m})
+## Return the filter coefficients of a Hamming window of length @var{m}.
+##
+## For a definition of the Hamming window, 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 Hamming window
+
+function c = hamming (m)
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  if (! (isscalar (m) && (m == fix (m)) && (m > 0)))
+    error ("hamming: M has to be an integer > 0");
+  endif
+
+  if (m == 1)
+    c = 1;
+  else
+    m = m - 1;
+    c = 0.54 - 0.46 * cos (2 * pi * (0:m)' / m);
+  endif
+
+endfunction
+
+%!assert (hamming (1), 1);
+%!assert (hamming (2), (0.54 - 0.46)*ones(2,1));
+%!assert (hamming (16), fliplr (hamming (16)));
+%!assert (hamming (15), fliplr (hamming (15)));
+%!test
+%! N = 15;
+%! A = hamming (N);
+%! assert (A (ceil (N/2)), 1);
+
+%!error hamming ();
+%!error hamming (0.5);
+%!error hamming (-1);
+%!error hamming (ones(1,4));