Re: NR 1.2.3 Upbeats: confusing explanation of measurePosition

[Federico Bruni]

Il 31/12/2012 00:23, Trevor Daniels ha scritto:
> Federico, you wrote Sunday, December 30, 2012 10:59 PM
>
>
> > In NR 1.2.3, Upbeats:
> >
> > """
> > So \partial 8 becomes:
> >
> > \time 3/4
> > \set Timing.measurePosition = #(ly:make-moment -1 8)
> > e8 | a4 c8 b c4 |
> >
> > _The property measurePosition contains a rational number indicating how
> > much of the measure has passed at this point_. Note that this is set to
> > a negative number by the \partial command: i.e., \partial 4 is
> > internally translated to -4, meaning “there is a quarter note left in
> > the measure.”
> > """
> >
> > IMO the first sentence is a bit confusing.
> > What the number says actually is "how much of the measure is needed to
> > complete the time signature", 1/8 in the example above. This implicitely
> > says how much of the measure has passed at this point: 3/4 - 1/8 = 5/8
>
> Because the time in the measure is calculated modulo the time
> signature the position -1/8 is the same as 5/8 in 3/4 time.  But -1/8
> is at position 5/8 in the /previous/ bar.

Ok, that is bar 0

> The text tries to explain what \partial does, which is count backwards
> over the anacrusis.  If you set measurePosition to 5/8 it looks the same
> as it does when set to -1/8, but the bar numbering will be 1 off.

Ok, I see.
I think that we should try to explain it better, even if it's not easy.
As pointed out by Rheinold, we should stress the fact that partial bar 
is measure 0.

Thanks
--
Federico