Tetracot extensions

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Tetracot has multiple competing extensions to the 7-limit. The simplest 2.3.5.11 subgroup commas of tetracot are ptolemisma (100/99) and rastma (243/242), and it can be viewed as the merge of the two corresponding rank-3 temperaments. 100/99 is particularly tricky as it can suggest tempering out either 225/224 (leading to apollo) or 385/384 (leading to supermagic), resulting in distinct extensions of tetracot:

  • Monkey (34 & 41) – tempering out 100/99, 243/242, 385/384
  • Bunya (34d & 41) – tempering out 100/99, 225/224, 243/242

The two unite in 41et, where both 225/224 and 385/384 are tempered out.

In addition, there are two simpler entries:

  • Modus (27e & 34d) – tempering out 64/63, 100/99, 243/242
  • Wollemia (27e & 34) – tempering out 56/55, 100/99, 243/242

The two unite in 27et, where both 56/55 and 64/63 are tempered out.

Another possible path, which is a weak extension, is to temper out 441/440, 540/539, or 2401/2400, leading to octacot, discussed separately.

Interval chain

Monkey

# Cents* Approximate Ratios
0 0.00 1/1
1 175.62 11/10, 10/9
2 351.24 11/9, 16/13
3 526.87 15/11
4 702.49 3/2
5 878.11 5/3
6 1053.73 11/6, 24/13
7 29.36 55/54, 45/44, 40/39
8 204.98 9/8
9 380.60 5/4
10 556.22 11/8, 18/13
11 731.85 20/13
12 907.47 22/13
13 1083.09 13/7, 15/8
14 58.71 33/32, 27/26, 25/24
15 234.34 8/7, 15/13
16 409.96
17 585.58 45/32
18 761.20
19 936.83 12/7
20 1112.45
21 88.07
22 263.69
23 439.31 9/7
24 614.94 10/7
25 790.56 11/7
26 966.18
27 1141.80 27/14
28 117.43 15/14
* in 13-limit POTE tuning

Bunya

# Cents* Approximate Ratios
0 0.00 1/1
1 175.89 11/10, 10/9
2 351.77 11/9, 16/13
3 527.66 15/11
4 703.54 3/2
5 879.43 5/3
6 1055.31 11/6, 24/13
7 31.20 56/55, 55/54, 45/44, 40/39
8 207.09 9/8
9 382.97 5/4
10 558.86 11/8, 18/13
11 734.74 20/13
12 910.63 22/13
13 1086.52 28/15, 15/8
14 62.40 33/32, 28/27, 27/26, 25/24
15 238.29 15/13
16 414.17 14/11
17 590.06 7/5
18 765.94 14/9
19 941.83
20 1117.72 21/11
21 93.60 21/20
22 269.49 7/6
23 445.37
24 621.26
25 797.15
26 973.03 7/4
27 1148.92 35/18
28 124.80 14/13
* in 13-limit POTE tuning

Modus

# Cents* Approximate Ratios
0 0.00 1/1
1 176.95 11/10, 10/9
2 353.91 11/9, 16/13
3 530.86 15/11
4 707.81 3/2
5 884.77 5/3
6 1061.72 11/6, 24/13, 13/7
7 38.67 55/54, 45/44, 40/39, 36/35
8 215.63 9/8, 8/7
9 392.58 5/4
10 569.53 11/8, 18/13
11 746.49 20/13
12 923.44 22/13, 12/7
13 1100.39 15/8, 40/21
14 77.35 27/26, 25/24, 22/21
15 254.30 15/13
16 431.25 9/7
17 608.20 10/7
18 785.16 11/7
19 962.11
20 1139.06 27/14
21 116.02 15/14
* in 13-limit POTE tuning

Wollemia

# Cents* Approximate Ratios
0 0.00 1/1
1 177.23 11/10, 10/9
2 354.46 11/9, 16/13
3 531.69 15/11
4 708.92 3/2
5 886.16 5/3
6 1063.39 11/6, 24/13, 28/15
7 40.62 55/54, 45/44, 40/39
8 217.85 9/8
9 395.08 5/4, 14/11
10 572.31 11/8, 18/13, 7/5
11 749.54 20/13, 14/9
12 926.77 22/13
13 1104.01 15/8
14 81.24 27/26, 25/24
15 258.47 15/13, 7/6
16 435.70
17 612.93
18 790.16
19 967.39 7/4
20 1144.62
21 121.86 14/13
* in 13-limit POTE tuning

Tuning spectra

Monkey

Gencom: [2 10/9; 100/99 105/104 144/143 243/242]

Gencom mapping: [⟨1 1 1 5 2 4], ⟨0 4 9 -15 10 -2]]

Eigenmonzo
(Unchanged-interval) 		Generator
(¢) 		Comments
11/10 165.004
11/9 173.704
14/13 174.746
12/11 174.894
11/8 175.132
14/11 175.300 11-odd-limit minimax
8/7 175.412
7/6 175.428
9/7 175.438
4/3 175.489
15/14 175.694
7/5 175.729 7, 9, 13 and 15-odd-limit minimax
13/11 175.899
16/15 176.021
5/4 176.257 5-odd-limit minimax
18/13 176.338
15/13 176.516
6/5 176.872
13/10 176.890
13/12 176.905
15/11 178.984
16/13 179.736
10/9 182.404

Bunya

Gencom: [2 10/9; 100/99 144/143 225/224 243/242]

Gencom mapping: [⟨1 1 1 -1 2 4], ⟨0 4 9 26 10 -2]]

Eigenmonzo
(Unchanged-interval) 		Generator
(¢) 		Comments
11/10 165.004
11/9 173.704
12/11 174.894
11/8 175.132
15/14 175.427
7/5 175.442 11-odd-limit minimax
4/3 175.489
8/7 175.724
7/6 175.767 7-odd-limit minimax
9/7 175.829 9-odd-limit minimax
13/11 175.899 13 and 15-odd-limit minimax
14/13 176.011
16/15 176.021
14/11 176.094
5/4 176.257 5-odd-limit minimax
18/13 176.338
15/13 176.516
6/5 176.872
13/10 176.890
13/12 176.905
15/11 178.984
16/13 179.736
10/9 182.404

Modus

Gencom: [2 10/9; 64/63 78/77 100/99 144/143]

Gencom mapping: [⟨1 1 1 4 2 4], ⟨0 4 9 -8 10 -2]]

Eigenmonzo
(Unchanged-interval) 		Generator
(¢) 		Comments
11/10 165.004
11/9 173.704
12/11 174.894
11/8 175.132
4/3 175.489
13/11 175.899
16/15 176.021
5/4 176.257 5-odd-limit minimax
18/13 176.338
15/13 176.516
14/11 176.805 11, 13 and 15-odd-limit minimax
6/5 176.872
13/10 176.890
13/12 176.905
15/14 177.116
9/7 177.193 9-odd-limit minimax
7/5 177.499 7-odd-limit minimax
7/6 177.761
14/13 178.617
8/7 178.897
15/11 178.984
16/13 179.736
10/9 182.404

Wollemia

Gencom: [2 10/9; 56/55 91/90 100/99 243/242]

Gencom mapping: [⟨1 1 1 0 2 4], ⟨0 4 9 19 10 -2]]

Eigenmonzo
(Unchanged-interval) 		Generator
(¢) 		Comments
11/10 165.004
11/9 173.704
12/11 174.894
11/8 175.132
4/3 175.489
13/11 175.899
16/15 176.021
5/4 176.257 5-odd-limit minimax
18/13 176.338
15/13 176.516
6/5 176.872
13/10 176.890
13/12 176.905
8/7 177.307 7, 9, 11, 13 and 15-odd-limit minimax
14/13 177.538
7/6 177.791
7/5 178.251
9/7 178.629
15/11 178.984
14/11 179.723
16/13 179.736
15/14 180.093
10/9 182.404
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