Toine Schreurs wrote:
The transposition of the instrument does not depend on the key of the
music. On a B-flat sax a written C sounds as a B-flat. That's all
the information you need.
So use \transpose bf c' {the music}
And indeed, key E-major goes to F-sharp-major. The original
transposition from E-major to G-flat-major implies an A-sharp
saxophone.
At the root of this is the possibility that there should/could be two
modes of transpose.
1) "Tonal" transpose: which would use double{flats,sharps} when
appropriate. e.g. (as in this case) a G in E major is a flattened third,
so when transposed to G-flat major *should* become a B-doubleflat.
2) "Atonal" transpose: which would favour the simplest spelling. e.g. G
transposed up a tone would *always* become A.