Re: Terminology of baseMoment, beats, groups

[David Kastrup]

Urs Liska <address@hidden> writes:

> Am 11.11.2017 um 11:42 schrieb David Kastrup:
>> Urs Liska <address@hidden> writes:
>>
>>> So, now the first question ...
>>>
>>> The terminology of baseMoment, beats and groups is inconsistent
>>> between the NR
>>> (http://lilypond.org/doc/v2.19/Documentation/notation/beams#setting-automatic-beam-behavior)
>>> and the code. The question is, what are the components of the
>>> following:
>>>
>>>    \set baseMoment = #(ly:make-moment 1/8)
>>>    \set beatStructure = 3,3,2
>>>
>>>  From the text in the NR this would be three beats, divided in three or
>>> two base moments each.
>>> However, the C++ code (and the code comments) refer(s) to that as
>>> three groups with three beats each.
>> Can you please come up with actual quotes/evidence for those statements?
>> Neither of those make much sense, so I'd guess you'd been
>> over-paraphrasing either.  Or alternatively, there are grave errors in
>> the respective description which warrant fixing rather than unifying
>> first.
>>
>
> a) from the NR section linked
> "beatStructure is a scheme list that defines the length of each beat
> in the measure in units of baseMoment. "
>
> I read this as: In the given example beatStructure is a list that
> defines the measure to consist of three beats. Beat one and two have
> the length of three baseMoments of 1/8, beat three is two baseMoments
> of 1/8 long.
>
> Actually this is consistent with how I would describe that measure in
> prose: we have an 8/8 measure with three beats, with lengths 3, 3, and
> 2 quavers.

I have a hard time seeing a "beat" as something that can have different
lengths.  It's more of an "accent" to me.  beatStructure's naming,
however, is consistent with that doc section.  I almost suspect this to
have been designed/written by a dancer: those have slightly different
terminology.

> b) from beaming-pattern.cc
>
> 1) line 206ff., comment to find_location()
> /*
>    Get the group start position, the next group starting position, and the
>    next beat starting position, given start_moment, base_moment,
>    grouping, and factor
> */
>
> 2) line 265, comment right after find_location has been called:
> // Mark the importance of stems that start at a beat or a beat group.
>
> From the actual behaviour of the code (and other comments throughout
> the code) it is clear that "beat" refers to a baseMoment unit and
> "group" refers to the entity the NR calls "beat".
> The context property "beatStructure" obviously corresponds to the C++
> variable "grouping".

I find "grouping" without "beat" fine.  I could have been responsible
for the terminology in the code (pretty sure I wasn't, but it matches
the terminology I use quite better).

Now I have certainly not gotten an English music education, so can
someone who did chime in?

-- 
David Kastrup