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1 ## Copyright (C) 1995, 1996, 1997 Andreas Weingessel |
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2 ## |
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3 ## This program is free software; you can redistribute it and/or modify |
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4 ## it under the terms of the GNU General Public License as published by |
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5 ## the Free Software Foundation; either version 2, or (at your option) |
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6 ## any later version. |
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7 ## |
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8 ## This program is distributed in the hope that it will be useful, but |
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9 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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11 ## General Public License for more details. |
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12 ## |
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13 ## You should have received a copy of the GNU General Public License |
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14 ## along with this file. If not, write to the Free Software Foundation, |
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15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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16 |
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17 ## usage: hanning (m) |
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18 ## |
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19 ## Returns the filter coefficients of a Hanning window of length m. |
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20 ## |
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21 ## For a definition of this window type, see e.g. A. V. Oppenheim & |
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22 ## R. W. Schafer, "Discrete-Time Signal Processing". |
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23 |
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24 ## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at> |
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25 ## Description: Coefficients of the Hanning window |
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26 |
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27 function c = hanning (m) |
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28 |
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29 if (nargin != 1) |
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30 usage ("hanning (m)"); |
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31 endif |
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32 |
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33 if !(is_scalar (m) && (m == round (m)) && (m > 0)) |
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34 error ("hanning: m has to be an integer > 0"); |
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35 endif |
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36 |
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37 if (m == 1) |
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38 c = 1; |
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39 else |
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40 m = m - 1; |
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41 c = 0.5 - 0.5 * cos (2 * pi * (0 : m)' / m); |
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42 endif |
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43 |
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44 endfunction |