1729/1728: Difference between revisions

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{{Infobox Interval
{{Infobox Interval
| Icon =  
| Name = ramanujanisma
| Ratio = 1729/1728
| Color name = 19o3oz2, nothozo 2nd,<br>Nothozo comma
| Monzo = -6 -3 0 1 0 1 0 1
| Comma = yes
| Cents = 1.00158
| Name = massma, <br>ramanujanisma, <br>dodecentisma
| Color name =
| FJS name =
| Sound =  
}}
}}
'''1729/1728''' is a [[19-limit]] (more accurately, 2.3.7.13.19 subgroup) [[superparticular]] interval and an [[unnoticeable comma]]. '''Massma'''<ref>referring to number 1728 being known as the ''Maß'' in German. </ref>, '''ramanujanisma'''<ref>referring to the anecdotal story of [[Wikipedia: Ramanujan|Ramanujan]] finding 1729 an interesting number. </ref>, and '''dodecentisma'''<ref>referring to the size being close to the cent relative to 12edo. </ref> have been proposed as the name. The comma forms the difference between the [[octave]] and a stack of [[7/6]], [[13/12]] and [[19/12]].
'''1729/1728''', known as the '''ramanujanisma''', is a [[19-limit]] (more accurately, 2.3.7.13.19 [[subgroup]]) [[superparticular]] interval and an [[unnoticeable comma]] that is remarkably close to one cent in size. It forms the difference between the [[octave]] and a stack of [[7/6]], [[13/12]] and [[19/12]], and less likely, the difference between [[19/18]] and [[96/91]], which in turn is [[8/7]] less [[13/12]] or [[16/13]] less [[7/6]].  


Both the numerator and denominator of this interval are famous in mathematics. [[Wikipedia: 1728 (number)|1728]], being 12 to the 3rd power, is also known as mass. [[Wikipedia:1729 (number)|1729]] is known for being Ramanujan's number and the first number that can be expressed as the sum of two cubes in two different ways (1729 = 1<sup>3</sup> + 12<sup>3</sup> = 9<sup>3</sup> + 10<sup>3</sup>).
Both the numerator and denominator of this interval are famous in mathematics. [[Wikipedia: 1728 (number)|1728]], being 12 to the 3rd power, is also known as mass. [[Wikipedia:1729 (number)|1729]] is known for being Ramanujan's number and the first number that can be expressed as the sum of two cubes in two different ways (1729 = 1<sup>3</sup> + 12<sup>3</sup> = 9<sup>3</sup> + 10<sup>3</sup>).


Remarkably, this comma is very close to one cent.  
== Commatic relations ==
This comma is the difference between the following superparticular pairs:
* [[91/90]] and [[96/95]]
* [[133/132]] and [[144/143]]
* [[273/272]] and [[324/323]]
* [[325/324]] and [[400/399]]
* [[361/360]] and [[456/455]]
* [[385/384]] and [[495/494]]
* [[513/512]] and [[729/728]] *
* [[1001/1000]] and [[2376/2375]]
* [[1216/1215]] and [[4096/4095]]
* [[1225/1224]] and [[4200/4199]]
* [[1521/1520]] and [[12636/12635]]
* [[1540/1539]] and [[14080/14079]]
* [[1701/1700]] and [[104976/104975]]
* [[1716/1715]] and [[228096/228095]]
<nowiki>*</nowiki> all is within the 2.3.7.13.19 subgroup


Tempering out this comma enables the related essentially tempered chords in the 19-odd-limit.  
It factors into the following superparticular pairs:
* [[2926/2925]] and [[4225/4224]]
* [[2431/2430]] and [[5985/5984]]
* [[2401/2400]] and [[6175/6174]]
* [[2080/2079]] and [[10241/10240]]
 
== Temperaments ==
Tempering out this comma in the 19-limit leads to the rank-7 '''ramanujanismic temperament''', or in the 2.3.7.13.19 subgroup, the rank-4 '''ramanujanic temperament'''. In either case it enables the [[ramanujanismic chords]], the [[essentially tempered chord]]s in the 19- or 21-odd-limit. The basic equivalence related to all these chords can be expressed as (7/6)(13/12)(19/12)~2/1, similar to (7/5)(11/10)(13/10)~2/1 as is enabled by the [[1001/1000|sinbadma (1001/1000)]]. Futhermore, [[8/7]] is short of a stack consisting of 19/18 and 13/12, [[16/13]] short of a stack consisting of 19/18 and 7/6, and [[32/19]] short of a stack consisting of 7/6 and 13/9, all by the ramanujanisma, so that any accurate tuning of the 2.3.13.19, 2.3.7.19, or 2.3.7.13 subgroup will naturally have an accurate approximation to [[7/1|7]], [[13/1|13]], or [[19/1|19]], respectively.
 
== Terminology ==
The name ''ramanujanisma'' was first proposed by [[User:Fredg999|Frédéric Gagné]] in reference to the anecdotal story of [[Wikipedia: Ramanujan|Ramanujan]] finding 1729 an interesting number. Alternative names include ''lesser massma'', proposed by [[User:Eliora|Eliora]], in reference to the number 1728 being known as the ''Maß'' in German, and ''dodecentisma'', proposed by [[User:Godtone|Godtone]], in reference to the size being close to the relative ''cent'' of ''12''edo (''dodeca'') (12 × 100 = 1200 and this comma is a low [[prime limit]] superparticular approximating 1/1200 of an octave) and in reference to 1728 being a power of 12 (''dodeca'').  


== See also ==
== See also ==
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* [[Unnoticeable comma]]
* [[Unnoticeable comma]]


== Notes ==
[[Category:Ramanujanismic]]
 
[[Category:Commas named after mathematicians]]
[[Category:19-limit]]
[[Category:Commas referencing a famous use of a number]]
[[Category:Unnoticeable comma]]
[[Category:Superparticular]]