Re: NR 1.2.3 Upbeats: confusing explanation of measurePosition

[Federico Bruni]

2012/12/31 Colin Hall <address@hidden>

> On Mon, Dec 31, 2012 at 10:20:38AM +0100, Federico Bruni wrote:
> > Il 31/12/2012 00:52, Reinhold Kainhofer ha scritto:
> > >On 2012-12-30 23:59, Federico Bruni wrote:
> > >>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.
> > >
> > >I agree about confusion, but not in the first sentence, but in the last:
> > >-4 actually means "it needs one quarter note until the measure even
> > >starts". (\partial inserts a partial measure 0 before the measure 1, and
> > >measure 1 is the first measure where counting starts)
> > >
> >
> > Ok, I would say "it needs one quarter note until the _first_ measure
> > starts" and explain that using a non-negative number would result in
> > setting the partial measure as measure 1 instead of measure 0.
>
> Thanks for the report, Federico, and to the others for their analysis.
>
> Could you collate a well-formed doc enhancement request and post it?
> Then I can create a tracker for the change.
>
>
>

Hi Colin,

no issue has been created so far.
I can try to formulate a doc enhancement request for what I was asking, not
for the discussion about the term "rational number", raised by Eluze.

This sentence:

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.”


The first sentence is clear when positive numbers are used, not when
negative numbers are used. In particular, it's not saying clearly what's
happening in the counting of bars. So I would say:

"""
The property measurePosition contains a rational number, which is usually
positive and indicates how much of the measure has passed at this point.
The \partial command sets it to a negative number: i.e., \partial 4 is
internally translated to #(ly:make-moment -1 4). The negative number has a
different meaning: it says that the current (first) bar will be
@emph{preceded} by a bar 0 (the partial bar) which lasts a quarter.
"""

Ugly description, I know, but you should get the point.
Thanks,
Federico