Re: Measurement units for Stem Length (and in general)

[Trevor Daniels]

Graham Percival wrote Monday, October 06, 2008 10:50 AM


> On Sun, 5 Oct 2008 19:50:54 -0700 (PDT)
> Jonathan Wilkes <address@hidden> wrote:
>
> >      I'm confused why the stem length shouldn't normally be 3 for a
> > stem that spans three spaces.  In the Internals Reference for stem,
> > the unit for the setting "length" is given as "dimension, in staff
> > space."  How is that different than a number? Is there a reference
> > table somewhere that lists the units of measurement used by Lilypond?
>
> NR 3.4.3 Distances and measurements ?
>
> That said, this section of the docs is still being worked on, so
> it may be unclear or contain inaccuracies.

It may indeed, and it certainly does not contain
a complete answer to this question.  The length of
a stem is one of the few that is specified in half
staff spaces (although the Internal Reference uses
the global description which says just "staff spaces").

Even so, why isn't 6.0 the correct length in this
example.  I think it is because the staff space is
defined as the distance of the white space between
two adjacent staff lines, ie the thickness of the
staff line is not included.  Can anyone confirm this?

The units of space-space (for distances) and 
line-thickness (for thicknesses) are quite distinct
and can be varied independently, but it would be
useful to know the conversion factor between them
for their default settings.  I've not been able to
determine this so far ... help, anyone?

Trevor