Akjaysma
| Interval information |
5/7-octave comma
reduced subharmonic
(Shannon, [math]\sqrt{nd}[/math])
The akjaysma is an unnoticeable 7-limit comma. It is the difference between a stack of seven 105/64's and five octaves; [47 -7 -7 -7⟩ in monzo and 0.338 cents in size. For equal divisions N up to 37316, this comma is tempered out only if 7 divides N. Examples are 7edo, 77edo, 217edo, 224edo, 441edo and 665edo.
Temperaments
Tempering out the akjaysma splits the octave into 7 equal parts and maps 105th harmonic into 5\7. It leads to a number of regular temperaments including absurdity, brahmagupta, and neutron.
In addition, akjaysma appears in temperaments whose period is a multiple of 7 (14, 21, 28, 35, etc.), however from a composer's standpoint it may not be the most prominent characterization of these temperaments due to a lot of inherent differences between multiples of 7edo. Tempering it out along with the landscape comma offers the aptly named 441 & 1407 akjayland temperament, that divides the octave into 7 x 3 = 21 parts.
Akjaysmic
Subgroup: 2.3.5.7
Comma list: [47 -7 -7 -7⟩
Mapping: [⟨7 0 0 47], ⟨0 1 0 -1], ⟨0 0 1 -1]]
- mapping generators: ~1157625/1048576, ~3, ~5
Optimal tuning (POTE): ~1157625/1048576 = 1\7, ~3/2 = 701.965, ~5/4 = 386.330
Optimal ET sequence: 140, 224, 301, 441, 665, 742, 966, 1106, 1407, 1547, 1848, 2289, 2513, 2954, 3395, 4802
In higher limits, akjaysmic rank-3 temperament can be described as the 441 & 1848 & 2954 temperament, and it tempers out 184549376/184528125 and 199297406/199290375 in the 11-limit. See 7th-octave temperaments.
Etymology
This comma was named by Aaron Krister Johnson in 2011 after himself[1].