100/99: Difference between revisions

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[[de:100/99]]
[[de:100/99]]
{{Infobox Interval
{{Infobox Interval
| Icon =
| Ratio = 100/99
| Ratio = 100/99
| Monzo = 2 -2 2 0 -1
| Monzo = 2 -2 2 0 -1
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In [[just intonation]], '''100/99''', the '''Ptolemy's comma''' or '''ptolemisma''', is a [[superparticular]] interval of around 17.4¢ which makes the difference between [[11/10]], the greater undecimal neutral second of about 165¢, and [[10/9]], the 5-limit minor whole tone of about 182.4¢. Temperaments in which 100/99 is tempered out include [[22edo]], [[41edo]] and others; in such systems, 11/10 and 10/9 are equated. This is in contrast to the more familiar tempering out of [[81/80]], which results in meantone and other temperaments, in which 10/9 is equated, not with 11/10, but with [[9/8]]. Along with being the difference between 11/10 and 10/9, 100/99 is the amount by which an [[11/8]] and two [[6/5]]s fall short of an octave, so that tempering out 100/99 allows for the [[ptolemismic triad]] which has intervals of 11/8, 6/5, 6/5.
In [[just intonation]], '''100/99''', the '''Ptolemy's comma''' or '''ptolemisma''', is a [[superparticular]] interval of around 17.4¢ which makes the difference between [[11/10]], the greater undecimal neutral second of about 165¢, and [[10/9]], the 5-limit minor whole tone of about 182.4¢. Temperaments in which 100/99 is tempered out include [[22edo]], [[41edo]] and others; in such systems, 11/10 and 10/9 are equated. This is in contrast to the more familiar tempering out of [[81/80]], which results in meantone and other temperaments, in which 10/9 is equated, not with 11/10, but with [[9/8]]. Along with being the difference between 11/10 and 10/9, 100/99 is the amount by which an [[11/8]] and two [[6/5]]s fall short of an octave, so that tempering out 100/99 allows for the [[ptolemismic triad]] which has intervals of 11/8, 6/5, 6/5.


== See Also ==
== See also ==
 
* [[Ptolemismic triad]]
* [[Rank-4 temperament #Ptolemismic (100/99)]]
* [[Ptolemismic clan]], the clan of rank-3 temperaments where it is tempered out
* [[Small comma]]
* [[List of superparticular intervals]]
* [[Gallery of just intervals]]
* [[Gallery of just intervals]]


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[[Category:Small comma]]
[[Category:Small comma]]
[[Category:Superparticular]]
[[Category:Superparticular]]
[[Category:Ptolemismic]]

Revision as of 10:28, 1 March 2022

Interval information
Ratio 100/99
Factorization 22 × 3-2 × 52 × 11-1
Monzo [2 -2 2 0 -1
Size in cents 17.39948¢
Names Ptolemy's comma,
ptolemisma
Color name 1uyy1, luyoyo comma
FJS name [math]\displaystyle{ \text{A1}^{25}_{11} }[/math]
Special properties square superparticular,
reduced
Tenney norm (log2 nd) 13.2732
Weil norm (log2 max(n, d)) 13.2877
Wilson norm (sopfr(nd)) 31
Open this interval in xen-calc

In just intonation, 100/99, the Ptolemy's comma or ptolemisma, is a superparticular interval of around 17.4¢ which makes the difference between 11/10, the greater undecimal neutral second of about 165¢, and 10/9, the 5-limit minor whole tone of about 182.4¢. Temperaments in which 100/99 is tempered out include 22edo, 41edo and others; in such systems, 11/10 and 10/9 are equated. This is in contrast to the more familiar tempering out of 81/80, which results in meantone and other temperaments, in which 10/9 is equated, not with 11/10, but with 9/8. Along with being the difference between 11/10 and 10/9, 100/99 is the amount by which an 11/8 and two 6/5s fall short of an octave, so that tempering out 100/99 allows for the ptolemismic triad which has intervals of 11/8, 6/5, 6/5.

See also