243/242: Difference between revisions

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More accurate description of the ragisma's function
m Temperaments: Specify Rastmic as rank-4 temperament
 
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{{interwiki
| de = 243/242
| en = 243/242
| es =
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{{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
[[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 ==
[[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.


'''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|cents]]. 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]] as well as the difference between [[11/9]] and [[27/22]], and, the difference between [[45/44]] and [[55/54]]. Tempering it out leads to a form of '''[[rastmic temperaments|rastmic temperament]]''' or '''neutral temperament'''. When not tempered out, the rastma serves as the difference between nearby 11-limit chromas– a property that becomes especially apparent when one works extensively with 33/32 quartertones.  
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 chords]]
* [[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]]