3 doctitle = "Transposing music with minimum accidentals"
5 texidoc = "There is a way to enforce enharmonic modifications for
6 notes in order to have the minimum number of accidentals. In this
7 case, the following rules apply:
9 \"Double accidentals should be removed, as well as E sharp (-> F),
10 C flat (-> B), F flat (-> E) and B sharp (-> C)\".
12 In this manner, the most natural enharmonic notes are chosen.
15 #(define (naturalize-pitch p)
16 (let* ((o (ly:pitch-octave p))
17 (a (* 4 (ly:pitch-alteration p)))
18 ; alteration, a, in quarter tone steps, for historical reasons
19 (n (ly:pitch-notename p)))
21 ((and (> a 1) (or (eq? n 6) (eq? n 2)))
24 ((and (< a -1) (or (eq? n 0) (eq? n 3)))
28 ((> a 2) (set! a (- a 4)) (set! n (+ n 1)))
29 ((< a -2) (set! a (+ a 4)) (set! n (- n 1))))
30 (if (< n 0) (begin (set! o (- o 1)) (set! n (+ n 7))))
31 (if (> n 6) (begin (set! o (+ o 1)) (set! n (- n 7))))
32 (ly:make-pitch o n (/ a 4))))
34 #(define (naturalize music)
35 (let* ((es (ly:music-property music 'elements))
36 (e (ly:music-property music 'element))
37 (p (ly:music-property music 'pitch)))
39 (ly:music-set-property!
41 (map (lambda (x) (naturalize x)) es)))
43 (ly:music-set-property!
48 (set! p (naturalize-pitch p))
49 (ly:music-set-property! music 'pitch p)))
53 #(define-music-function (parser location m)
57 music = \relative c' { c4 d e g }
61 \transpose c ais \music
62 \naturalizeMusic \transpose c ais \music
63 \transpose c deses \music
64 \naturalizeMusic \transpose c deses \music
66 \layout { ragged-right = ##t }