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Val temperament notation

🔗Gene Ward Smith <gwsmith@svpal.org>

5/4/2005 5:15:59 PM

Here is an idea for notating the notes of a temperament which I have
had for a while, but haven't seen any clear use for. I'm posting about
it anyway, hoping Micawber like that something will turn up.

If we have an r2 ("linear") temperament, we have a canonical defining
wedgie for it. If we take the complement, wedge it with a monzo, and
take the complement again, we get a val. The val defines the
corresponding note 9in the temperament: the interval we started from,
and all intervals differing by commas of the temperament from it, are
sent to zero by this val. The val is the val notation for a note in
the temperament.

Given a pair of rational generators (for example 2 and 3/2 for
meantone, or 21/20 and 27/25 for ennealimmal) we can express the
interval in val notaton in terms of these generators, using the
corresponding vals v1 and v2 for the generators g1 and g2. Since these
are presumed to be generators, v1(g1)=v2(g2)=0, but also v1(g2)=+-1,
v2(g1)=+-1. Using this, it is immediate to translate val notation to
notation in terms of a pair of generators.

Val notation is entirely canonical, in no way depending on a choice of
generators, which is an interesting and concievably useful feature.
The vals of a given temperament form a two-dimensional sublattice of
val space, the space defined here:

http://66.98.148.43/~xenharmo/top.htm

This gives us an interesting geometric picture of the notes of an r2
temperament, which we can put into a rectangular array. Distance
between notes in this array is not Euclidean, but I suppose we are
used to that by now. The generators in such a picture could be chosen
to be minimal in size to make it as clear as possible; for instance
27/25 and 21/20 for ennealimmal.