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[project @ 2007-10-12 06:40:56 by jwe]
author jwe
date Fri, 12 Oct 2007 06:41:26 +0000
parents 34f96dd5441b
children a1dbe9d80eee
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1 ## Copyright (C) 1995, 1996, 1997 Andreas Weingessel
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 3 of the License, or (at
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8 ## your option) any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, see
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17 ## <http://www.gnu.org/licenses/>.
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18
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19 ## -*- texinfo -*-
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20 ## @deftypefn {Function File} {} blackman (@var{m})
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21 ## Return the filter coefficients of a Blackman window of length @var{m}.
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22 ##
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23 ## For a definition of the Blackman window, see e.g. A. V. Oppenheim &
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24 ## R. W. Schafer, "Discrete-Time Signal Processing".
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25 ## @end deftypefn
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26
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27 ## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at>
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28 ## Description: Coefficients of the Blackman window
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29
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30 function c = blackman (m)
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31
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32 if (nargin != 1)
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33 print_usage ();
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34 endif
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35
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36 if (! (isscalar (m) && (m == round (m)) && (m > 0)))
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37 error ("blackman: m has to be an integer > 0");
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38 endif
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39
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40 if (m == 1)
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41 c = 1;
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42 else
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43 m = m - 1;
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44 k = (0 : m)' / m;
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45 c = 0.42 - 0.5 * cos (2 * pi * k) + 0.08 * cos (4 * pi * k);
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46 endif
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47
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48 endfunction