matthiasm@8: %
matthiasm@8: %DEGREES2QUALITY convert a degreelist to chord quality enumeration
matthiasm@8: % 
matthiasm@8: % [quality,success, errormessage] = degrees2quality(degreelist, {verbose})
matthiasm@8: % 
matthiasm@8: % Converts a list of degree strings to an integer value denoting the
matthiasm@8: % chord's quality. Quality values are from the enumeration:
matthiasm@8: %
matthiasm@8: % 0   Major
matthiasm@8: % 1   Minor
matthiasm@8: % 2   Diminished
matthiasm@8: % 3   Augmented
matthiasm@8: % 4   Suspended
matthiasm@8: %
matthiasm@8: % Success = 1 if symbols parsed correctly, 0 otherwise. 
matthiasm@8: %
matthiasm@8: % If optional argument 'verbose' is 1, function prints any errormessage to 
matthiasm@8: % the screen.
matthiasm@8: % 
matthiasm@8: % calls:    degrees2semitones
matthiasm@8: % 
matthiasm@8: % returns:  quality (integer)
matthiasm@8: %           success  (boolean)  
matthiasm@8: %           errormessage (string)
matthiasm@8: %
matthiasm@8: %
matthiasm@8: % Author: Christopher Harte,  August 2005
matthiasm@8: % 
matthiasm@8: % Copyright: Centre for Digital Music, Queen Mary University of London 2005 
matthiasm@8: %
matthiasm@8: % This file is part of the C4DM Chord Toolkit.  
matthiasm@8: %
matthiasm@8: % The C4DM Chord Toolkit is free software; you can redistribute it and/or 
matthiasm@8: % modify it under the terms of the GNU General Public License as published 
matthiasm@8: % by the Free Software Foundation; either version 2 of the License, or
matthiasm@8: % (at your option) any later version.
matthiasm@8: %
matthiasm@8: % The C4DM Chord Toolkit is distributed in the hope that it will be useful,
matthiasm@8: % but WITHOUT ANY WARRANTY; without even the implied warranty of
matthiasm@8: % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
matthiasm@8: % GNU General Public License for more details.
matthiasm@8: %
matthiasm@8: % You should have received a copy of the GNU General Public License
matthiasm@8: % along with the C4DM Toolkit; if not, write to the Free Software
matthiasm@8: % Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
matthiasm@8: 
matthiasm@8: %
matthiasm@8: function [quality,success,errormessage] = degrees2quality(degreelist,verbose)
matthiasm@8: 
matthiasm@8: 
matthiasm@8: 
matthiasm@8: 
matthiasm@8: quality = '';
matthiasm@8: errormessage = '';
matthiasm@8: 
matthiasm@8: if nargin < 2
matthiasm@8:     verbose = 0;
matthiasm@8: end
matthiasm@8: 
matthiasm@8: % define templates for the 5 different triad chords (four quality families
matthiasm@8: % plus suspension) - weights mean maj thirds will have more effect than min
matthiasm@8: % 3rds which in turn have more effect than 5ths and then 2nds and 4ths
matthiasm@8: 
matthiasm@8: templates = [[1,0,0,0,6,0,0,4,0,0,0,0]; ... % maj
matthiasm@8:              [1,0,0,5,0,0,0,4,0,0,0,0]; ... % min
matthiasm@8:              [1,0,0,5,0,0,4,0,0,0,0,0]; ... % dim
matthiasm@8:              [1,0,0,0,6,0,0,0,4,0,0,0]; ... % aug
matthiasm@8:              [1,0,2,0,0,2,0,4,0,0,0,0]];    % sus
matthiasm@8:              
matthiasm@8:          
matthiasm@8: % get the semitone equivalents of the degrees in the degree list             
matthiasm@8: [semitones,success,error] = degrees2semitones(degreelist);
matthiasm@8: 
matthiasm@8: indexa = 1;
matthiasm@8: 
matthiasm@8: % initialise a binary vector showing which semitones are present 
matthiasm@8: present = zeros(1,12);
matthiasm@8: 
matthiasm@8: while indexa <= 3 && indexa <= length(semitones) 
matthiasm@8:     
matthiasm@8:     % for each of the first three semitones in the list make its position a
matthiasm@8:     % one in the vector 'present' 
matthiasm@8:     
matthiasm@8:     if semitones(indexa) < 12
matthiasm@8:     
matthiasm@8:         present(semitones(indexa)+1) = 1;
matthiasm@8:     
matthiasm@8:     end
matthiasm@8:     indexa = indexa +1;
matthiasm@8:     
matthiasm@8: end
matthiasm@8: 
matthiasm@8: % multiply present by the templates matrix to give a vector of scores for
matthiasm@8: % the possible qualities
matthiasm@8: qvector = templates * present';
matthiasm@8: 
matthiasm@8: 
matthiasm@8: % find maximum value from the qualities vector
matthiasm@8: % this function benfits from the max function's picking of the first
matthiasm@8: % maximum value if there are several equal ones so is predisposed toward 
matthiasm@8: % major if the quality is not obvious from the input. (e.g. C:(1) returns major)  
matthiasm@8: [value,index] = max(qvector);
matthiasm@8: 
matthiasm@8: % take 1 from index to give correct enumeration
matthiasm@8: quality = index-1;
matthiasm@8: 
matthiasm@8: 
matthiasm@8: if(success==0) 
matthiasm@8: 
matthiasm@8:     errormessage = sprintf([error 'Error in degrees2quality: incorrect degree in list "' degreelist '"\n']);
matthiasm@8:     
matthiasm@8:     if verbose == 1
matthiasm@8:         fprintf(1, errormessage);
matthiasm@8:     end
matthiasm@8: end