Re: [PATCH] autochange.scm: Use averaged chord pitches to determine staff.

[Mark Knoop]

At 10:50 on 22 Jul 2009, David Kastrup wrote:
> Mark Polesky <address@hidden> writes:
> 
> > Anyway, I think that it would make a lot more sense if the staff
> > were determined by the "average" pitch of the chord.
> 
> I don't think so.  The purpose of staff changes is to avoid help
> lines. In particular where they would require systems to be paced
> further apart.  For this, the average is irrelevant, only the total
> range (top and bottom note lines) is of interest.  A staff change is
> a drastic measure: one will not typically do it unless more than two
> help lines would otherwise occur.  So it is really a matter of the
> total vertical extent (after considering the signature, so an f flat
> counts as higher as an e sharp, never mind that its pitch is lower)
> and not the pitch average.
> 

I presume by "help lines" you mean ledger lines?

But you're correct that neither the average pitch or even the average
pitch of the outer notes of the chord is enough. 

Consider the following:

<d' f'>8 <b, f'> <d' f'> <b, f'>

Clearly this would be best set in the bass clef, however the average
pitches (e', gis) would (probably) result in it swapping between the
two staves. 

So it's actually the extremity of the chord in the direction of
potential staff change that is of primary importance.

-- 
Mark Knoop