Mauch MIREX 2010

%

%DEGREE2NOTE convert a degree to correctly spelled note w.r.t. a root

% 

% [note,success,errormessage] = degree2note(degree, root {verbose})

% 

% Converts a degree to a note (string) with root as reference note 

% for degree interval.

% 

% Success = 1 if degree is converted correctly, 0 otherwise.

% 

% If optional argument 'verbose' is 1, function prints any errormessage to 

% the screen.

%

% returns:  note (string)

%           success (boolean)

%           errormessage (string)

%

% See also degrees2notes, parsenote.

%

%

% Author: Christopher Harte,  August 2005

% 

% Copyright: Centre for Digital Music, Queen Mary University of London 2005 

%

% This file is part of the C4DM Chord Toolkit.  

%

% The C4DM Chord Toolkit 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 2 of the License, or

% (at your option) any later version.

%

% The C4DM Chord Toolkit 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 the C4DM Toolkit; if not, write to the Free Software

% Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

%

function [note,success,errormessage] = degree2note(degree, root,verbose)

if nargin < 3

    verbose = 0;

end

errormessage = '';

error1 = '';

error2 = '';

note = [];

intervaltranslation = [5,0,2,4,-1,1,3,5]; % scale degree translations on line of fifths 

fifthpositions = {'F','C','G','D','A','E','B'}; %order of naturals on line of fifths

success = 1;

% parse the root note

[rootnatural,rootaccs, rsuccess, error1] = parsenote(root);

%parse the degree

[interval, degreeaccs, present, dsuccess, error2] = parsedegree(degree);

% if parsing symbols was successful

if(rsuccess && dsuccess);

    switch(rootnatural) % find root natural position on line of fifths

        case 'F'

            fifthindex = 0;        

        case 'C'

            fifthindex = 1;

        case 'G'

            fifthindex = 2;

        case 'D'

            fifthindex = 3;

        case 'A'

            fifthindex = 4;

        case 'E'

            fifthindex = 5;

        case 'B'

            fifthindex = 6;

    end

    %locate enharmonic root on line of fifths (modulo 6 arithmetic)   

    fifthoffset = rootaccs*7;

    fifthindex = fifthindex + fifthoffset;

    % calculate interval translation on line of fifths (add 1 to account

    % for matlab referencing of array elements... 

    intervaloffset = intervaltranslation(mod(interval,7)+1); 

    finalposition = fifthindex + intervaloffset;

    naturalvalue = mod(finalposition,7);

    % calculate number of accidentals

    if finalposition <0 

        %if final position is negative then calculate number of flats

        % remembering to include the extra first flat (-1)

        accidentals = fix((finalposition+1)/7) + degreeaccs -1;

    else

        % note is a natural or has a number of sharps

        accidentals = fix(finalposition/7) + degreeaccs;

    end

    note = fifthpositions(naturalvalue+1);

    if accidentals > 0

        for i=1:accidentals

            note = strcat(note, '#');

        end

    elseif accidentals <=0

        for i=1:abs(accidentals)

            note = strcat(note, 'b');

        end

    end

else

    success=0;

end

if(success==0) % correct degree therefore return success = 1 

    % if not an integer then the degree string is incorrect

    errormessage = [error1 error2 sprintf(['Error in degree2note: Unrecognised degree "' degree '" or root "' root '"\n'])]; 

    if verbose == 1

       fprintf(1,errormessage); 

    end

end