Schismic-Pythagorean equivalence continuum

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The schismic-Pythagorean equivalence continuum is a continuum of 5-limit temperaments which equate a number of schismas (32805/32768) with Pythagorean comma ([-19 12). This continuum is theoretically interesting in that these are all 5-limit temperaments supported by 12edo.

All temperaments in the continuum satisfy (32805/32768)n ~ [-19 12. Varying n results in different temperaments listed in the table below. It converges to schismic as n approaches infinity. If we allow non-integer and infinite n, the continuum describes the set of all 5-limit temperaments supported by 12edo due to it being the unique equal temperament that tempers both commas and thus tempers all combinations of them. The just value of n is approximately 12.0078623975…, and temperaments having n near this value tend to be the most accurate ones – indeed, the fact that this number is so close to 12 reflects how small Kirnberger's atom (the difference between 12 schismas and the Pythagorean comma) is.

Temperaments with integer n
n Temperament Comma
Ratio Monzo
-1 Gracecordial 17433922005/17179869184 [-34 20 1
0 Compton 531441/524288 [-19 12
1 Meantone 81/80 [-4 4 -1
2 Diaschismic 2048/2025 [11 -4 -2
3 Misty 67108864/66430125 [26 -12 -3
4 Undim [41 -20 -4
5 Quindromeda [56 -28 -5
6 Sextile [71 -36 -6
7 Sepsa-sepgu (12&323) [86 -44 -7
8 World calendar [101 -52 -8
9 Quinbisa-tritrigu (12&441) [116 -60 -9
10 Lesa-quinbigu (12&494) [131 -68 -10
11 Quadtrisa-legu (12&559) [146 -76 -11
12 Atomic [161 -84 -12
13 Quintrila-theyo (12&677) [-176 92 13
Schismic 32805/32768 [-15 8 1

We may invert the continuum by setting m such that 1/m + 1/n = 1. This may be called the syntonic-Pythagorean equivalence continuum, which is essentially the same thing. The just value of m is 1.0908441588…

Temperaments with integer m
m Temperament Comma
Ratio Monzo
-1 Python 43046721/41943040 [-23 16 -1
0 Compton 531441/524288 [-19 12
1 Schismic 32805/32768 [-15 8 1
2 Diaschismic 2048/2025 [11 -4 -2
3 Augmented 128/125 [7 0 -3
4 Diminished 648/625 [3 4 -4
5 Ripple 6561/6250 [-1 8 -5
6 Wronecki 531441/500000 [-5 12 -6
Meantone 81/80 [-4 4 -1
Temperaments with fractional n and m
Temperament n m
Passion 5/3 = 1.6 5/2 = 2.5
Quintaleap 5/2 = 2.5 5/3 = 1.6

Python

Python is generated by a fifth, which is typically flatter than 7\12. The ~5/4 is reached by sixteen fifths octave-reduced, which is a double augmented second (C-Dx). It can be described as 12 & 91, and 103edo is a good tuning.

Subgroup: 2.3.5

Comma list: [-23 16 -1 = 43046721/41943040

Mapping[1 0 -23], 0 1 16]]

mapping generators: ~2, ~3

Wedgie⟨⟨1 16 23]]

Optimal tunings:

  • POTE: ~2 = 1\1, ~3/2 = 699.030

Optimal ET sequence12, …, 79, 91, 103

Badness: 0.295079

Sextile

See also: Landscape microtemperaments #Sextile

Subgroup: 2.3.5

Comma list: [71 -36 -6

Mapping[6 0 71], 0 1 -6]]]

mapping generators: ~4096/3645, ~3

Optimal tunings:

  • POTE: ~4096/3645 = 1\6, ~3/2 = 702.2356

Wedgie⟨⟨6 -36 -77]]

Optimal ET sequence12, …, 222, 234, 246, 258, 270, 1068, 1338, 1608, 1878, 4026bc

Badness: 0.555423