Graham Percival wrote:
1. Look at the selected snippets for \transpose.
There's an example that's very close to what he
wants.
I disagree.
That example modifies the enharmonic spelling of
notes in an already transposed section. We're looking
for a function to transpose each note individually by
the appropriate interval determined by its scale-
degree within a specfied tonality.
input:
\relative c' { \key c \major c4 d e f g a b c }
output:
\relative c' { \key c \major g4 a b c d e f g }
2. Look at
{ \displayMusic { a ais d dis } }
to get some info about how lilypond treats
pitches. The idea is to write a function that
translates "a ais" into "d dis".
Not at all. The idea is to write a function that,
given the key of C major, translates "a b" into
"e f".
3. Modify the existing example so that instead of
producing notes with few accidentals, it changes
the notename by the desired interval.
How is this helpful? This reminds me of the Monty
Python skit on how to play the flute: "You blow
there and you move your fingers up and down here."
Besides, this doesn't account for the fact that
different notes will need to be transposed by
different intervals.
If you cannot, or will not, describe what you
actually want, it's very difficult to help you.
He already has! He clearly stated that he wants to
transpose music down a 4th, diatonically:
http://lists.gnu.org/archive/html/lilypond-user/2008-12/msg00557.html
If you don't know what diatonic means, look it up!
So far, the only post that offers promise is from
John:
http://lists.gnu.org/archive/html/lilypond-user/2008-12/msg00591.html