Ploidacot/Alpha-dicot: Difference between revisions

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{{Breadcrumb}}
{{Breadcrumb}}{{Infobox ploidacot|Ploids=1|Shears=1|Cots=2|Pergen=[P8, P4/2]|Forms=5, 9, 14|Title=Alpha-dicot; omega-dicot}}'''Alpha-dicot''' is a temperament archetype where the generator is a [[Interseptimal interval|semitwelfth]], two of which make a perfect twelfth of [[3/1]], and the period is a [[2/1]] octave. Equivalently, the generator could be a semifourth, two of which make a [[4/3]], so '''omega-dicot''' means the same thing and is unused.


'''Alpha-dicot''' is a temperament archetype where the generator is a [[Interseptimal interval|semitwelfth]], two of which make a perfect twelfth of [[3/1]], and the period is a [[2/1]] octave. Equivalently, the generator could be a semifourth, two of which make a [[4/3]].
Alpha-dicot temperaments usually generate the [[5L 4s]] MOS structure, named "semiquartal" after the semifourth generator, as well as the child scale [[5L 9s]]. Alpha-dicot temperaments tend to involve interseptimal intervals, which are in between conventional diatonic intervals.
 
Alpha-dicot temperaments usually generate the [[5L 4s]] MOS structure, named "semiquartal" after the semifourth generator, and the more accurate tunings generate [[5L 9s]]. Alpha-dicot temperaments tend to involve interseptimal intervals, which are in between conventional diatonic intervals.


== Intervals and notation ==
== Intervals and notation ==
Alpha-dicot temperaments can be notated using [[Hemipyth#Notation|hemipyth notation]] with the semiquartal nicknames.
Alpha-dicot notation is complicated as it conventionally requires either the introduction of new "[[hemipythagorean]]" ordinals or the use of scales other than the standard diatonic scale. As such, there is no universally accepted convention. Note and interval names are provided where alpha-dicot intervals align with standard monocot intervals (which use [[Chain-of-fifths notation]]).
 
{| class="wikitable"
<!-- This is the dicot table, not the alpha-dicot one - TODO {| class="wikitable"
|+Alpha-dicot intervals (assuming pure octave and fifth)
|+Dicot intervals (assuming pure fifth and octave)
!#
!#
!Cents
!Cents
!Notation
!Notation
!Name
!Name
|-
| -10
|90.22
|Db
|minor second
|-
|-
| -9
| -9
|441.20
|1041.20
|Fd
|
|semidiminished fourth
|
|-
|-
| -8
| -8
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|-
|-
| -7
| -7
|1,143.16
|543.16
|Cd
|
|semidiminished octave
|
|-
|-
| -6
| -6
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|-
|-
| -5
| -5
|645.11
|45.11
|Gd
|
|semidiminished fifth
|
|-
|-
| -4
| -4
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|-
|-
| -3
| -3
|147.07
|747.07
|Dd
|
|neutral second
|
|-
|-
| -2
| -2
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|-
|-
| -1
| -1
|849.02
|249.02
|Ad
|
|neutral sixth
|
|-
|-
|0
|0
|0
|0
|C
|C
|perfect unison/perfect octave
|perfect unison
|-
|-
|1
|1
|350.98
|950.98
|Ed
|
|neutral third
|
|-
|-
|2
|2
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|-
|-
|3
|3
|1,052.93
|452.93
|Bd
|
|neutral seventh
|
|-
|-
|4
|4
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|-
|-
|5
|5
|554.89
|1154.89
|Ft
|
|semiaugmented fourth
|
|-
|-
|6
|6
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|-
|-
|7
|7
|56.84
|656.84
|Ct
|
|semiaugmented unison
|
|-
|-
|8
|8
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|-
|-
|9
|9
|758.80
|158.8
|Gt
|
|semiaugmented fifth
|
|-
|10
|1,109.78
|B
|major seventh
|}
|}
-->


== Temperament interpretations ==
== Temperament interpretations ==
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=== Bug ===
=== Bug ===
[[Bug]] is an exotemperament, equating the neutral semitwelfth to 5/3. This means that 9/5 is the same interval (tempering out [[27/25]]), and the neutral semifourth represents both 6/5 and 10/9. This is clearly badly inaccurate, but is probably the best 5-limit interpretation of this ploidacot.
[[Bug]] is an exotemperament, equating the semitwelfth generator to 5/3. This means that 9/5 is the same interval (tempering out [[27/25]]), and the semifourth represents both 6/5 and 10/9. This is clearly badly inaccurate, but is probably the best 5-limit interpretation of this ploidacot.


The best tunings tend to be around 940{{c}} for the semitwelfth, with a somewhat flat twelfth. This sets the semifourth to 260{{c}}, which is close to [[7/6]].
The best tunings tend to be around 940{{c}} for the semitwelfth, with a somewhat flat twelfth. This sets the semifourth to 260{{c}}, which is close to [[7/6]].


=== Semaphore ===
=== Semaphore ===
Given that bug sets the neutral semifourth close to 7/6, what happens if it is set equal to 7/6 in the 2.3.7 subgroup? Then, it is equated to [[8/7]], and [[49/48]] is tempered out. The neutral semitwelfth is equated to [[12/7]] and [[7/4]]. This is still an inaccurate temperament, but is on the edge as to whether it counts as exo.
Given that bug sets the semifourth close to 7/6, what happens if it is set equal to 7/6 in the 2.3.7 subgroup? Then, it is equated to [[8/7]], and [[49/48]] is tempered out. The semitwelfth is equated to [[12/7]] and [[7/4]]. This is still an inaccurate temperament, but is on the edge as to whether it counts as exo.


The best tunings tend to be around 950{{c}} here, with a far more accurate twelfth. But, just like how bug's semifourth generator was close to 7/6, this is close to [[26/15]].
The best tunings tend to be around 950{{c}} here, with a far more accurate twelfth. But, just like how bug's semifourth generator was close to 7/6, this is close to [[26/15]].


=== Barbados ===
=== Barbados ===
Here, the generator actually is 26/15, equated with [[45/26]]. This is a rather accurate temperament, tempering out the small comma of [[676/675]], but it is defined in the awkward 2.3.13/5 subgroup. The neutral semifourth here is [[15/13]][[~]][[52/45]].
Here, the generator actually is 26/15, equated with [[45/26]]. This is an accurate temperament, tempering out the unnoticeable comma of [[676/675]], but it is defined in the awkward 2.3.13/5 subgroup. The semifourth here is [[15/13]][[~]][[52/45]].


As the comma is so small, the best tunings are close to just. The semitwelfth is around 951{{c}}, leading to a near-just twelfth.
As the comma is so small, the best tunings are close to just. The semitwelfth is around 951{{c}}, leading to a near-just twelfth.
{{Todo| unify precision }}