Gregorian leap day: Difference between revisions

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400 is the number of years in the Gregorian calendar's leap cycle.
Gregorian leap day is a rank-2 temperament which is produced by temperament-merging 97edo, which has the cardinality of leap years in Gregorian calendar's cycle, and 400edo, the whole duration of the cycle.
== Theory ==
400 is the number of years in the Gregorian calendar's leap cycle. They are not spread evenly, but if they were, this would produce a scale with a 33\400 generator which is associated to [[18/17]] and [[55/52]], three of which make [[19/16]]. Because the generator is mapped to 18/17, the temperament can be seen as an octavated version of [[18/17 equal-step tuning]]. Gregorian leap day has mos of size 12, 13, 25, 37, 49, 61, 73, and 97. [[1L 11s]] mos of this temperament is a barely noticeable circulating temperament for [[12edo]].


400edo contains GregorianLeapDay[97] scale, which is a [[maximal evenness]] version of the leap rule currently in use in the world today. The scale has a 33\400 generator which is associated to [[18/17]] and [[55/52]], three of which make [[19/16]]. The corresponding temperament is 97 & 400, with comma list 2432/2431, 2601/2600, 2926/2925, 6175/6174, 17689/17680, and 22477/22440.   
In the 7-limit, temperament reaches [[15/8]] in 11 generators, entirely contained within the 12-tone well temperament, and also [[7/5]] in 18 generators.
[[Category: Rank 2]]
== Temperament data ==
Subgroup: 2.3.5.7
 
Comma list: 67108864/66976875, 6281023877654589/6250000000000000
 
{{mapping|legend=1| 1 10 -7 8 | 0 -102 113 131 }}
 
: mapping generators: ~2 = 1\1, 160000/151263 = 98.998
 
[[Support]]ing [[ET]]s: {{EDOs|97, 400}}, ...
 
=== 11-limit ===
 
Subgroup: 2.3.5.7.11


[[1L 11s]] mos of this temperament is an octavated variant of [[18/17 equal-step tuning|18/17s equal temperament]], and a barely noticeable circulating temperament for [[12edo]].
Comma list: 166698/166375, 422576/421875, 67108864/66976875
[[Category: Rank 2]]
 
{{mapping|legend=1| 1 10 -7 8 16 | 0 -102 113 131 -152 }}
 
: mapping generators: ~2 = 1\1, 69120/65219 = 98.998
 
[[Support]]ing [[ET]]s: {{EDOs|97, 303, 400}}, ...
 
=== 13-limit ===
 
Subgroup: 2.3.5.7.11.13
 
Comma list: 676/675, 4096/4095, 166698/166375, 105644/105625
 
{{mapping|legend=1| 1 10 -7 8 16 7 | 0 -102 113 131 -152 -40 }}
 
: mapping generators: ~2 = 1\1, 55/52 = 98.998
 
[[Support]]ing [[ET]]s: {{EDOs|97, 303, 400}}, ...
 
=== 17-limit ===
 
Subgroup: 2.3.5.7.11.13.17
 
Comma list: 676/675, 4096/4095, 11016/11011, 14400/14399, 93639/93500
 
{{mapping|legend=1| 1 10 -7 8 16 7 -12 | 0 -102 113 131 -152 -40 195 }}
 
: mapping generators: ~2 = 1\1, 55/52 = 98.998
 
[[Support]]ing [[ET]]s: {{EDOs|97, 303, 400}}, ...
 
=== 19-limit ===
 
Subgroup: 2.3.5.7.11.13.17
 
Comma list: 676/675, 2926/2925, 4096/4095, 6175/6174, 11016/11011, 14400/14399
 
{{mapping|legend=1| 1 10 -7 8 16 7 -12 4 | 0 -102 113 131 -152 -40 195 3}}
 
: mapping generators: ~2 = 1\1, 55/52 = 98.998
 
[[Support]]ing [[ET]]s: {{EDOs|97, 303, 400}}, ...

Revision as of 00:52, 5 June 2023

Gregorian leap day is a rank-2 temperament which is produced by temperament-merging 97edo, which has the cardinality of leap years in Gregorian calendar's cycle, and 400edo, the whole duration of the cycle.

Theory

400 is the number of years in the Gregorian calendar's leap cycle. They are not spread evenly, but if they were, this would produce a scale with a 33\400 generator which is associated to 18/17 and 55/52, three of which make 19/16. Because the generator is mapped to 18/17, the temperament can be seen as an octavated version of 18/17 equal-step tuning. Gregorian leap day has mos of size 12, 13, 25, 37, 49, 61, 73, and 97. 1L 11s mos of this temperament is a barely noticeable circulating temperament for 12edo.

In the 7-limit, temperament reaches 15/8 in 11 generators, entirely contained within the 12-tone well temperament, and also 7/5 in 18 generators.

Temperament data

Subgroup: 2.3.5.7

Comma list: 67108864/66976875, 6281023877654589/6250000000000000

Mapping[1 10 -7 8], 0 -102 113 131]]

mapping generators: ~2 = 1\1, 160000/151263 = 98.998

Supporting ETs: 97, 400, ...

11-limit

Subgroup: 2.3.5.7.11

Comma list: 166698/166375, 422576/421875, 67108864/66976875

Mapping[1 10 -7 8 16], 0 -102 113 131 -152]]

mapping generators: ~2 = 1\1, 69120/65219 = 98.998

Supporting ETs: 97, 303, 400, ...

13-limit

Subgroup: 2.3.5.7.11.13

Comma list: 676/675, 4096/4095, 166698/166375, 105644/105625

Mapping[1 10 -7 8 16 7], 0 -102 113 131 -152 -40]]

mapping generators: ~2 = 1\1, 55/52 = 98.998

Supporting ETs: 97, 303, 400, ...

17-limit

Subgroup: 2.3.5.7.11.13.17

Comma list: 676/675, 4096/4095, 11016/11011, 14400/14399, 93639/93500

Mapping[1 10 -7 8 16 7 -12], 0 -102 113 131 -152 -40 195]]

mapping generators: ~2 = 1\1, 55/52 = 98.998

Supporting ETs: 97, 303, 400, ...

19-limit

Subgroup: 2.3.5.7.11.13.17

Comma list: 676/675, 2926/2925, 4096/4095, 6175/6174, 11016/11011, 14400/14399

Mapping[1 10 -7 8 16 7 -12 4], 0 -102 113 131 -152 -40 195 3]]

mapping generators: ~2 = 1\1, 55/52 = 98.998

Supporting ETs: 97, 303, 400, ...