4 texidoc = "This example uses some Scheme code to enforce enharmonic
5 modifications for notes in order to have the minimum number of
6 accidentals. In this case, the following rules apply:
10 Double accidentals should be removed
26 In this manner, the most natural enharmonic notes are chosen.
28 doctitle = "Transposing music with minimum accidentals"
31 #(define (naturalize-pitch p)
32 (let* ((o (ly:pitch-octave p))
33 (a (* 4 (ly:pitch-alteration p)))
34 ; alteration, a, in quarter tone steps, for historical reasons
35 (n (ly:pitch-notename p)))
37 ((and (> a 1) (or (eq? n 6) (eq? n 2)))
40 ((and (< a -1) (or (eq? n 0) (eq? n 3)))
44 ((> a 2) (set! a (- a 4)) (set! n (+ n 1)))
45 ((< a -2) (set! a (+ a 4)) (set! n (- n 1))))
46 (if (< n 0) (begin (set! o (- o 1)) (set! n (+ n 7))))
47 (if (> n 6) (begin (set! o (+ o 1)) (set! n (- n 7))))
48 (ly:make-pitch o n (/ a 4))))
50 #(define (naturalize music)
51 (let* ((es (ly:music-property music 'elements))
52 (e (ly:music-property music 'element))
53 (p (ly:music-property music 'pitch)))
55 (ly:music-set-property!
57 (map (lambda (x) (naturalize x)) es)))
59 (ly:music-set-property!
64 (set! p (naturalize-pitch p))
65 (ly:music-set-property! music 'pitch p)))
69 #(define-music-function (parser location m)
73 music = \relative c' { c4 d e g }
77 \transpose c ais \music
78 \naturalizeMusic \transpose c ais \music
79 \transpose c deses \music
80 \naturalizeMusic \transpose c deses \music