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.