X-Git-Url: https://git.creatis.insa-lyon.fr/pubgit/?p=CreaPhase.git;a=blobdiff_plain;f=octave_packages%2Fm%2Fsignal%2Fblackman.m;fp=octave_packages%2Fm%2Fsignal%2Fblackman.m;h=7339519266cfbd54564131767d3872b96abbd7de;hp=0000000000000000000000000000000000000000;hb=1c0469ada9531828709108a4882a751d2816994a;hpb=63de9f36673d49121015e3695f2c336ea92bc278

diff --git a/octave_packages/m/signal/blackman.m b/octave_packages/m/signal/blackman.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} {} blackman (@var{m})
+## Return the filter coefficients of a Blackman window of length @var{m}.
+##
+## For a definition of the Blackman 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 Blackman window
+
+function c = blackman (m)
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  if (! (isscalar (m) && (m == fix (m)) && (m > 0)))
+    error ("blackman: M has to be an integer > 0");
+  endif
+
+  if (m == 1)
+    c = 1;
+  else
+    m = m - 1;
+    k = (0 : m)' / m;
+    c = 0.42 - 0.5 * cos (2 * pi * k) + 0.08 * cos (4 * pi * k);
+  endif
+
+endfunction
+
+%!assert (blackman (1), 1);
+%!assert (blackman (2), zeros(2,1), 1e-6);
+%!assert (blackman (16), fliplr (blackman (16)));
+%!assert (blackman (15), fliplr (blackman (15)));
+%!test
+%! N = 9;
+%! A = blackman (N);
+%! assert (A (ceil (N/2)), 1, 1e-6);
+%! assert ([A(1), A(length (A))], zeros (1, 2), 1e-6);
+
+%!error blackman ();
+%!error blackman (0.5);
+%!error blackman (-1);
+%!error blackman (ones(1,4));