Highly composite EDO: Difference between revisions
m Eliora moved page Highly melodic EDO to Highly composite EDO: discussion in #wiki on discord, highly composite forms the basis of the theory and superabundant is just a secondary term |
No edit summary |
||
| Line 1: | Line 1: | ||
Highly | '''Highly composite EDO''' is a tuning with [[Wikipedia:Highly composite number|highly composite number]] of pitches in an octave. They are the opposite of [[Prime EDO]]s. | ||
Contrast this with zeta EDOs, that approximate just intonation well, being highly harmonic EDOs. | |||
Contrast this with zeta EDOs, that approximate just intonation well, being highly harmonic EDOs. | |||
== Superabundant and highly composite numbers in EDOs == | == Superabundant and highly composite numbers in EDOs == | ||
| Line 19: | Line 12: | ||
The factor of being relative to the number's size is important. For example, [[36edo|36]] has a sum of divisors of 91, while 130 has a sum of divisors of 252. If all the sub-scales were stretched end-to-end, this means 36 has 91 notes, and 130 has 252. However, 91/36 = 2.527, while 252/130 = 1.938, meaning that 36 carries a more impressive task in replicating sub-EDOs and symmetrical chords relative to it's size. | The factor of being relative to the number's size is important. For example, [[36edo|36]] has a sum of divisors of 91, while 130 has a sum of divisors of 252. If all the sub-scales were stretched end-to-end, this means 36 has 91 notes, and 130 has 252. However, 91/36 = 2.527, while 252/130 = 1.938, meaning that 36 carries a more impressive task in replicating sub-EDOs and symmetrical chords relative to it's size. | ||
== The difference == | == The difference of superabundant vs. highly composite == | ||
The difference between SA and HC is the following: the highly composite numbers count the amount of divisors, that is sub-EDOs, going to a record., while superabundant EDOs count the amount of note in those divisors if they were stretched end-to-end. | |||
The first 19 superabundant and highly composite numbers are the same. | |||
An example when they are not the same: [[50400edo|50400]] is the 27th highly composite number, that is not on the superabundant list. The count of divisors of 50400 is 108, which means it supports 106 symmetrical scales that aren't the chromatic and whole-octave scale. However, by the note count in all those scales, which is 102311 not counting 1 and 50400, the EDO lags slightly behind [[27720edo]], with it's coefficient being 4.05 and 50400edo's coefficient being 4.03. This means that while 27720 is less composite than 50400, it carries a more impressive task in providing notes to compose with, if the composer is interested in smaller EDOs as subscales. | An example when they are not the same: [[50400edo|50400]] is the 27th highly composite number, that is not on the superabundant list. The count of divisors of 50400 is 108, which means it supports 106 symmetrical scales that aren't the chromatic and whole-octave scale. However, by the note count in all those scales, which is 102311 not counting 1 and 50400, the EDO lags slightly behind [[27720edo]], with it's coefficient being 4.05 and 50400edo's coefficient being 4.03. This means that while 27720 is less composite than 50400, it carries a more impressive task in providing notes to compose with, if the composer is interested in smaller EDOs as subscales. | ||
| Line 43: | Line 40: | ||
=== Largerly composite numbers === | === Largerly composite numbers === | ||
Largely composite numbers are a variant of a sequence of | Largely composite numbers are a variant of a sequence of numbers where the divisor count is nondecreasing, as opposed to strictly increasing in the case of highly composite numbers. | ||
First few are (OEIS: A067128): {{EDOs|1, 2, 3, 4, 6, 8, 10, 12, 18, 20, 24, 30, 36, 48, 60, 72, 84, 90, 96, 108, 120, 168, 180, 240, 336, 360, 420, 480, 504, 540, 600, 630, 660, 672, 720, 840, 1080, 1260, 1440, 1680, 2160, 2520, 3360, 3780, 3960, 4200, 4320, 4620, 4680, 5040, 7560, 9240}}. | First few are (OEIS: A067128): {{EDOs|1, 2, 3, 4, 6, 8, 10, 12, 18, 20, 24, 30, 36, 48, 60, 72, 84, 90, 96, 108, 120, 168, 180, 240, 336, 360, 420, 480, 504, 540, 600, 630, 660, 672, 720, 840, 1080, 1260, 1440, 1680, 2160, 2520, 3360, 3780, 3960, 4200, 4320, 4620, 4680, 5040, 7560, 9240}}. | ||