Changing reference pitches (for use in n-ET)

[Hans Aberg]

For typesetting in n-ET, n not a multiple of 12, I think I need to  
change the reference pitches that "make-pitch" uses (that is the  
values produced by the note named 0-6). (By some experimenting in 53- 
ET, it seems not enough merely changing the "alter" field, as  
LilyPond uses the reference pitches as departure for computing the  
note names.)

Specifically, if LilyPond currently sets the major second (whole  
tonestep) M to 1/6 = 2/12, then I want to be able to change this  
value so that the minor second m (semitone) is equal to (P8 - 5M)/2,  
where P8 is the perfect octave (rational interval 2), and so that the  
reference pitch numbered 5 in the middle octave plays an A4 = 440.0  
Hz in the MIDI. With this system, one can produce the 53-ET  
Pythagorean scale by setting M = 9/53, and the 31-ET Just Intonation  
by M = 5/31.

  Hans Åberg