Re: Contemporary music required feature #1: chromatic transposition

[Hans Aberg]

On 22 Sep 2009, at 11:16, Joseph Wakeling wrote:

> Hans Aberg wrote:
> > > What you see is that
> > >
> > >  (i) without naturalizeMusic, transposition fails: transposition  
> > > alone
> > >      leaves the final pitch being 'g+5/4' which has no accidental
> >
> > I think is just a bug. Somehow the sharp drops out.
>
> It's not so much a bug as a notational impossibility.
>
> Think of pitch as being staff position s plus alteration a.  The  
> latter
> is used to determine the accidental.  So in this case we're dealing  
> with
> a base pitch of g+1, which is displayed as g-double-sharp.
>
> Now you transpose it up a quarter-tone, so all pitches are altered by
> +1/4.  Your pitch is now g+5/4 and there is no accidental for +5/4  
> so of
> course one can't be displayed.

The correct accidental is a # plus a !/4. It then does not change the  
scale degree. This will also be correct in if the sharp and microtonal  
accents are relative a tuning system other than E12.

> So, if there _is_ a bug, it's that Lilypond doesn't recognise that an
> alteration of >1 should change the staff position.

In this case, staff position only changes if enharmonic equivalents  
are applied. This is how it should be.

>   The question is, how to incorporate
> a well-defined chromatic transposition rule as an option in Lilypond  
> as
> opposed to a function à la naturalizeMusic?

The staff system is what I call diatonic. It cannot be changed,  
because that is how it was designed around year 1600. I made a  
description of it using minor, major and neutral seconds. I can think  
of generalizations, where the staff indicates an arbitrary choice  
pitches, but I do not think that musicians could read it.

So you want is a mixture if the traditional system and enharmonic  
equivalents.

  Hans