21edf: Difference between revisions

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{{Infobox ET}}
{{Infobox ET}}
'''[[EDF|Division of the just perfect fifth]] into 21 equal parts''' (21EDF) is related to [[36edo|36 edo]], but with the 3/2 rather than the 2/1 being just. The octave is about 3.3514 cents stretched and the step size is about 33.4264 cents. Unlike 36edo, it is only consistent up to the [[3-odd-limit|4-integer-limit]], with discrepancy for the 5th harmonic.
'''[[EDF|Division of the just perfect fifth]] into 21 equal parts''' (21EDF) is related to [[36edo|36 edo]], but with the 3/2 rather than the 2/1 being just. The octave is about 3.3514 cents stretched and the step size is about 33.4264 cents. Unlike 36edo, it is only consistent up to the 4-[[integer-limit]], with discrepancy for the 5th harmonic.


Lookalikes: [[36edo]], [[57edt]]
Lookalikes: [[36edo]], [[57edt]]


=Approximations=
==Approximations==
==Harmonics==
===Harmonics===
{{Harmonics in equal|21|3|2|prec=2|columns=15}}
{{Harmonics in equal|21|3|2|prec=2|columns=15}}


==3-limit (Pythagorean) approximations (same as 7edf):==
===3-limit (Pythagorean) approximations (same as 7edf):===
2/1 = 1200 cents; 36 degrees of 21edf = 1203.3514... cents.
2/1 = 1200 cents; 36 degrees of 21edf = 1203.3514... cents.


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128/81 = 792.180... cents; 24 degrees of 21edf = 802.2342... cents.
128/81 = 792.180... cents; 24 degrees of 21edf = 802.2342... cents.
==7-limit approximations:==
===7-limit approximations:===
===7 only:===
====7 only:====
7/4 = 968.826... cents; 29 degrees of 21edf = 969.3664... cents.
7/4 = 968.826... cents; 29 degrees of 21edf = 969.3664... cents.


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64/49 = 462.348... cents; 14 degrees of 21edf = 467.97... cents.
64/49 = 462.348... cents; 14 degrees of 21edf = 467.97... cents.
===3 and 7:===
====3 and 7:====
7/6 = 266.871... cents; 8 degrees of 21edf = 267.4114... cents.
7/6 = 266.871... cents; 8 degrees of 21edf = 267.4114... cents.


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63/32 = 1172.736... cents; 35 degrees of 21edf = 1169.925... cents.
63/32 = 1172.736... cents; 35 degrees of 21edf = 1169.925... cents.


==Intervals==
The following table gives an overview of all degrees of 36edo.
The following table gives an overview of all degrees of 36edo.
{| class="wikitable"
{| class="wikitable mw-collapsible"
|+ Intervals of 21edf
|-
|-
! |Degree
! |Degree
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|}
|}
{{todo|expand}}