250/243: Difference between revisions

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a medium comma
Approximation: 24edo itself does not qualify as a chromium tuning
 
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[[de:250/243]]
{{Interwiki
'''250/243''', known as the '''porcupine [[Comma|comma]]''' or maximal diesis, is an interval of size 49.166 [[cent|cents]]. It is the amount by which two [[10/9|minor whole tones]] exceed a minor third, that is, (10/9)^2/(6/5). Tempering it out leads to [[5-limit|5-limit]] [[Porcupine_family|porcupine temperament]].
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{{Infobox Interval
| Name = porcupine comma, maximal diesis
| Color name = y<sup>3</sup>1, triyo 1sn,<br>y<sup>3</sup>M, triyoma
| Comma = yes
}}
'''250/243''' is known as the '''porcupine comma''' or the '''maximal diesis'''. Measuring about 49{{cent}}, it is a [[medium comma]]. It is the amount by which two [[10/9|minor whole tones]] exceed a minor third, that is, (10/9)<sup>2</sup>/(6/5). It is also the difference between [[25/24]] and [[81/80]], the two smallest [[5-limit]] [[superparticular]] ratios, and between three syntonic commas and the [[2187/2048|Pythagorean apotome]], putting it on the [[Syntonic&ndash;chromatic equivalence continuum]].
 
== Temperaments ==
Tempering it out leads to the [[5-limit]] [[porcupine]] temperament. See [[porcupine family]] for the family of rank-2 temperaments where it is tempered out.
 
== Approximation ==
250/243 is very close to one step of [[24edo]], which is the quarter tone that is exactly the half of [[12edo]] semitone. Therefore, if 250/243 is not tempered and instead is treated as an identity where it is equated with 1/24th of the octave, it serves as the period in the [[chromium]] temperament. (However, note that 24edo itself maps 250/243 inconsistently, and so chromium temperament starts at [[72edo]].) Thus in the framework of this temperament and the tuning systems associated with it, [[Eliora]] proposes the name ''chromium quartertone''.  


[[Category:5-limit]]
[[Category:Medium comma]]
[[Category:Porcupine]]
[[Category:Porcupine]]
 
[[Category:Commas named after compositions]]
[[Category:Todo:improve layout]]