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1 %
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2 % INTERVAL2SEMITONE
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3 %
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4 % [semitone, success, errormessage] = interval2semitone(interval, accidental, {verbose})
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5 %
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6 % Convert an interval and accidentals pair to a semitone value
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7 %
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8 % Success = 1 if interval converted correctly, 0 otherwise.
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9 %
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10 % If optional argument 'verbose' is 1, function prints any errormessage to
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11 % the screen.
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12 %
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13 % returns: semitone (string)
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14 % success (boolean)
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15 % errormessage (string)
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16 %
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17 % Author: Christopher Harte, August 2005
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18 %
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19 % Copyright: Centre for Digital Music, Queen Mary University of London 2005
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20 %
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21 % This file is part of the C4DM Chord Toolkit.
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22 %
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23 % The C4DM Chord Toolkit is free software; you can redistribute it and/or
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24 % modify it under the terms of the GNU General Public License as published
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25 % by the Free Software Foundation; either version 2 of the License, or
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26 % (at your option) any later version.
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27 %
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28 % The C4DM Chord Toolkit is distributed in the hope that it will be useful,
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29 % but WITHOUT ANY WARRANTY; without even the implied warranty of
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30 % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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31 % GNU General Public License for more details.
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32 %
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33 % You should have received a copy of the GNU General Public License
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34 % along with the C4DM Toolkit; if not, write to the Free Software
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35 % Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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36
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37 %
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38 function [semitone, success, errormessage] = interval2semitone(interval, accidentals, verbose)
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39
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40 if nargin < 3
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41 % verbose defaults 0
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42 verbose = 0;
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43 end
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44
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45 errormessage = '';
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46
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47 % semitone equivalents for intervals
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48 % interval 1,2,3,4,5,6,7
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49 semitonetranslation = [0,2,4,5,7,9,11];
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50
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51 semitone = 0;
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52
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53 success = 1;
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54
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55 if (interval > 0) && (interval < 50)
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56
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57 % semitone value is the number of semitones equivalent to the interval
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58 % added to the number of accidentals (sharps are positive, flats are
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59 % negative) and the number of octaves above the reference note to
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60 % account for extensions
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61
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62 semitone = semitonetranslation(mod(interval,8) + fix(interval/8)) + accidentals + 12*fix(interval/8);
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63
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64 else
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65 success = 0;
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66
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67 errormessage = sprintf('Error in interval2semitone: out of range interval "%d"\n', interval);
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68
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69 if verbose == 1
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70 fprintf(1,errormessage);
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71 end
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72 end
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73
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