Re: force accidentals

[Stephen]

Nicoas,

Mehmet meant to say "Can the function be modified to not put an accidental 
or natural on notes repeated in the same measure."

Put it another way and the question is: "Can we make the accidental engraver 
treat the natural exactly the way it treats the sharp and flat?"

In Atonal music, there is not key signature. Normally, if there are not 
accidentals in the key signature, that means the key is either C Major or a 
minor. So how do we indicate on paper that there is no key signature? 
Simple. Put the natural on the same footing as the sharp and flat, treat 
each note as if it has an equal chance of being a natural, sharp, or flat.

Accidentals are only normally put on a note the first time they occur in a 
measure, so we want the natural to be treated that way too. Instead of 
putting an accidental on every note, we want notes repeated in the same 
measure to be absent an accidental.

Somewhere in the function forceAlterations you might have the line:

(eqv? (ly:music-property m 'measureLength) 0)

checking to see whether the present note is the first occurance of that note 
(within the same octave, as Mehmet stated) since the measure began. Doing it 
that way would be cumbersome and might make the function more complicated 
than it would have to be, but I am indicating what the function should do to 
engrave Atonal music properly. Shoenberg did note approve to the term 
'Atonal'. However, this is how his music was originally published in the 
Universal Edition engravings. The proper term is 'Music without a Key 
Signature', but that is not as catchy as 'Atonal'.

So how would you enforce the idea that the music has no key signature when 
absence of accidentals in the key signature indicates C major? The answer is 
treating the natural the same as the other two accidentals.

This could be written into the accidental engraver as a standard style:

#(set-accidental-style 'atonal)

Stephen