243/242: Difference between revisions

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Added neutral temperament to this page as well- for now.
m Temperaments: Specify Rastmic as rank-4 temperament
 
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{{interwiki
| de = 243/242
| en = 243/242
| es =
| ja =
}}
{{Infobox Interval
{{Infobox Interval
| Icon =
| Name = rastma, neutral third comma
| Ratio = 243/242
| Color name = 1uu1, lulu 1sn,<br>Lulu comma
| Monzo = -1 5 0 0 -2
| Comma = yes
| Cents = 7.13912
| Name = rastma, <br>neutral third comma
| Color name =
| FJS name = A1<sub>121</sub>
| Sound =  
}}
}}
 
'''243/242''', the '''rastma''' or the '''neutral third comma''', is a [[small comma|small]] [[11-limit]] (also [[2.3.11 subgroup|2.3.11-subgroup]]) [[comma]] with a value of roughly 7.1 [[cent]]s. It is significant in [[just intonation]] as the amount by which a stack of two [[11/9]] neutral thirds (that is an Alpharabian narrow fifth
'''243/242''', the '''rastma''' or the '''neutral third comma''', is an [[11-limit]] (also 2.3.11 subgroup) comma with a value of roughly 7.1 [[cent]]s. It is significant in Just Intonation as the amount by which a stack of two [[33/32]] quartertones falls short of an [[2187/2048|apotome (2187/2048)]] as well as the difference between [[11/9]] and [[27/22]], and, the difference between [[45/44]] and [[55/54]]. The last makes the theory where the rastma serves as the [[Diatonic, Chromatic, Enharmonic, Subchromatic|subchroma]] that separates greater and lesser 11-limit chromas – a property that becomes especially apparent when one works extensively with the 11-limit.  
[[121/81]]) fall short of [[3/2]] just perfect fifth as well as the amount by which a stack of two [[27/22]] neutral thirds (that is an Alpharabian wide fifth [[729/484]]) exceeds a 3/2 just perfect fifth, the amount by which a stack of two [[33/32]] quartertones falls short of an [[2187/2048|apotome (2187/2048)]] as well as the difference between 11/9 and 27/22, and the difference between [[45/44]] and [[55/54]]. The last makes the theory where the rastma serves as the [[subchromatic|subchroma]] that separates greater and lesser 11-limit chromas – a theory that becomes especially useful when one works extensively with high-fidelity renditions of the 11-limit.


== Temperaments ==
== Temperaments ==
Tempering it out in the full 11-limit leads to the rastmic temperament, enabling [[rastmic chords]], or, in the 2.3.11 subgroup, the [[Subgroup temperaments #Neutral|neutral]] temperament, enabling [[Neutral tetrad|neutral chords]].
[[Tempering out]] this comma in the full 11-limit leads to the [[rastmic]] rank-4 temperament, or in the 2.3.11 subgroup, the [[neutral (temperament)|neutral]] temperament, enabling [[rastmic chords]] in either case.  
 
=== Rastmic temperament ===
 
Subgroup: 2.3.5.7.11
 
[[Comma list]]: 243/242
 
[[Mapping]]: [{{val| 1 1 0 0 2 }}, {{val| 0 2 0 0 5 }}, {{val| 0 0 1 0 0 }}, {{val| 0 0 0 1 0}}]
 
[[POTE generator]]s: ~11/9 = 350.5254, ~5/4 = 386.1653, ~7/4 = 968.6464
 
{{Val list|legend=1| 7d, 10, 14c, 17c, 24, 27e, 31, 41, 58, 72, 130, 202 }}
 
[[Badness]]: 0.05088 × 10<sup>-6</sup>
 
=== Neutral temperament ===
 
Subgroup: 2.3.11
 
[[Comma list]]: 243/242
 
[[Lp_tuning|POL2 generator]]: ~11/9 = 350.525
 
Gencom: [2 11/9; 243/242]
 
Gencom mapping: [&lt;1 1 0 0 2|, &lt;0 2 0 0 5|]
 
Map: [&lt;1 1 2|, &lt;0 2 5|]
 
EDOs: 7, 10, 17, 24, 41, 65, 89, 202, 291, 380


[[Tp_tuning#T2 tuning|RMS error]]: 0.3021 cents
See [[Rastmic clan]] for the clan of rank-2 temperaments where it is tempered out. See [[Rastmic rank three clan|Rastmic rank-3 clan]] for the clan of rank-3 temperaments where it is tempered out.


== See also ==
== See also ==
* [[Rastmic temperaments]], a collection of rank-3 temperaments where it is tempered out
* [[Rastmic chords]]
* [[Small comma]]
* [[List of superparticular intervals]]
* [[List of superparticular intervals]]


[[Category:11-limit]]
[[Category:Small comma]]
[[Category:Superparticular]]
[[Category:Rastmic]]
[[Category:Rastmic]]
[[Category:Neutral]]
[[Category:Neutral]]
[[Category:Commas named after musical traditions]]
[[Category:Commas named for the generator of their temperament]]

Latest revision as of 14:14, 13 July 2025

Interval information
Ratio 243/242
Factorization 2-1 × 35 × 11-2
Monzo [-1 5 0 0 -2
Size in cents 7.13912¢
Names rastma,
neutral third comma
Color name 1uu1, lulu 1sn,
Lulu comma
FJS name [math]\displaystyle{ \text{A1}_{11,11} }[/math]
Special properties superparticular,
reduced
Tenney height (log2 nd) 15.8437
Weil height (log2 max(n, d)) 15.8496
Wilson height (sopfr(nd)) 39
Comma size small
S-expression S9 / S11
Open this interval in xen-calc

243/242, the rastma or the neutral third comma, is a small 11-limit (also 2.3.11-subgroup) comma with a value of roughly 7.1 cents. It is significant in just intonation as the amount by which a stack of two 11/9 neutral thirds (that is an Alpharabian narrow fifth 121/81) fall short of 3/2 just perfect fifth as well as the amount by which a stack of two 27/22 neutral thirds (that is an Alpharabian wide fifth 729/484) exceeds a 3/2 just perfect fifth, the amount by which a stack of two 33/32 quartertones falls short of an apotome (2187/2048) as well as the difference between 11/9 and 27/22, and the difference between 45/44 and 55/54. The last makes the theory where the rastma serves as the subchroma that separates greater and lesser 11-limit chromas – a theory that becomes especially useful when one works extensively with high-fidelity renditions of the 11-limit.

Temperaments

Tempering out this comma in the full 11-limit leads to the rastmic rank-4 temperament, or in the 2.3.11 subgroup, the neutral temperament, enabling rastmic chords in either case.

See Rastmic clan for the clan of rank-2 temperaments where it is tempered out. See Rastmic rank-3 clan for the clan of rank-3 temperaments where it is tempered out.

See also