Systematic comma names explained: Difference between revisions

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Closing error: rework this section to more concisely explain the rules
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== Closing error ==
== Closing error ==
=== 31-comma, 21-23-comma, etc. ===
=== 31-comma, 21-23-comma, 11-3/5 comma, etc. ===
These types of comma names show the [[closing error]] of a specific [[interval]] in a specific [[edo]].
These types of comma names show the [[closing error]] of a specific [[interval]] in a specific [[edo]]. In general, an ''n''-''m''-comma, where ''n'' is a positive integer and ''m'' is a frequency ratio, is the difference between a stack of ''n'' instances of ''m'' and a number of octaves. ''m'' can be an integer, which means it is a harmonic. If the harmonic in question is the third harmonic (3/1), then it is left out of the comma name.  


For example, the ''31-5-comma'' is the difference between a stack of 31 5/4's (5/4 is the octave reduces harmonic 5), and 10 octaves, which is tempered out in 31edo.
An interval with a bigger denominator than numerator, like 3/5, indicates a negative interval. 3/5 for example is about -884 cents. A comma can still temper a stack of these. Just imagine it like a stack of 5/3's but going down instead of up. (In an edo, intervals that go down still wrap back around every octave, so this is possible.)


If the harmonic in question is the reduced third harmonic (3/2), then it is left out of the comma name. For example the 31-comma is the difference between a stack of 3/2's and a stack of octaves in 31edo.
For example, the ''31-5-comma'' is the difference between a stack of thirty-one 5/4's (5/4 is the octave-reduced harmonic 5) and 10 octaves, which is tempered out in 31edo. Meanwhile, the 31-comma is the difference between a stack of thirty-one 3/2's and eighteen octaves. As another example, the 11-3/5-comma is the difference between a stack of eleven 3/5's and minus eight octaves.  


These kinds of names can sometimes be mistaken for sagittal names (discussed later on this page) and vice versa, so be wary of that.
These kinds of names can sometimes be mistaken for sagittal names (discussed later on this page) and vice versa, so be wary of that.
=== 11-3/5 comma, 45-7/5 comma, etc. ===
These are the same type of name as above, but they involve stacks of intervals that are not octave reduced harmonics. For example 7/4 is an octave reduced harmonic, so a comma tempering a stack of those would be an ''n''-7 comma, but 7/5 is ''not'' a reduced harmonic, so a comma tempering a stack of those would be an ''n''-7/5 comma rather than just ''n''-7.
An interval with a bigger denominator than numerator, like 3/5, indicates a negative interval. 3/5 for example is about -884 cents. A comma can still temper a stack of these. Just imagine it like a stack of 5/3's but going down instead of up. (In an edo, intervals that go down still wrap back around every octave, so this is possible.)


=== 87-fold starling comma, etc. ===
=== 87-fold starling comma, etc. ===