Schisma: Difference between revisions

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: This revision was by author [[User:genewardsmith|genewardsmith]] and made on <tt>2011-08-08 15:40:51 UTC</tt>.<br>
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: The original revision id was <tt>244889805</tt>.<br>
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<h4>Original Wikitext content:</h4>
{{Infobox Interval
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| Ratio = 32805/32768
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| Name = schisma
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| Color name = Ly-2, Layo comma
| Comma = yes
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{{Wikipedia| Schisma }}
 
The '''schisma''', '''32805/32768''', is a small interval about 2 [[cent]]s. It arises as the difference between the [[Pythagorean comma]] and the [[syntonic comma]]. It is equal to ([[9/8]])<sup>4</sup>/([[8/5]]) and to ([[135/128]])/([[256/243]]) and also to ([[9/8]])<sup>3</sup>/([[64/45]]).  
 
== History and etymology ==
''Schisma'' is a borrowing of Ancient Greek, meaning "split". The term was first used by [[Boethius]] (6th century), in his ''De institutione musica'', using it to refer to half of the [[Pythagorean comma]]. The modern sense was introduced by [[Helmholtz]]' ''On the Sensations of Tone'', in particular the translation by [[Alexander Ellis]], where it is spelled ''skhisma''. Since it is extremely close to the [[superparticular]] ratio [[887/886]] {{nowrap|(2<sup>-1</sup> 443<sup>-1</sup> 887)}}, it is used interchangably with this interval in some of Helmholtz' writing.
 
== Temperaments ==
{{main|Schismatic family}}
Tempering out this comma gives a [[5-limit]] microtemperament called [[schismic|schismatic, schismic or helmholtz]], which if extended to larger [[subgroup]]s leads to the [[schismatic family]] of temperaments.
 
== Other intervals ==
 
Commas arising from the difference between a stack of Pythagorean intervals and other primes may also be called schismas. The difference between the [[Pythagorean comma]] and [[septimal comma]] is called the [[septimal schisma]]. Other examples are [[undevicesimal schisma]] and [[Alpharabian schisma]].
 
== Trivia ==
The schisma explains how the greatly composite numbers 1048576 (2<sup>20</sup>) and 104976 (18<sup>4</sup>) look alike in decimal. The largest common power of two between these numbers is 2<sup>5</sup>, (when 1049760 is written to equalize) and when reduced by that, 1049760/1048576 becomes 32805/32768.
 
== See also ==
* [[Pythagorean tuning]]
* [[Unnoticeable comma]]
 
[[Category:Schismatic]]
[[Category:Commas named for their regular temperament properties]]