Counterquectisma

Interval information

Factorization	2-500 × 3314 × 5
Monzo	[-500 314 1⟩
Size in cents	0.1839856¢
Names	counterquectisma, deltapion comma,
Color name	Quintritrilayo comma
FJS name	[math]\displaystyle{ \text{45d}{-31}^{5} }[/math]
Special properties	reduced, reduced harmonic
Tenney norm (log2 nd)	1000
Weil norm (log2 max(n, d))	1000
Wilson norm (sopfr(nd))	1947
Comma size	unnoticeable
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Counterquectisma, alternately deltapion comma, is an unnoticeable 5-limit comma.

Temperaments

It is associated with systems which have a precise perfect fifth, such as 359edo and 665edo. Tempering it out in the 5-limit produces rank-2 counterquectismic temperament. Equal tempereaments tempering out this comma include 359, 665, 1024, 1689, 3684, 4349, 7368, 8033.

Etymology

The comma was named by Eliora. First name derives from comma's monzo, number 500 being D in roman numerals, and phonetic alphabet for D is "delta", to which "pi" is added to signify 314, the decimal expansion of pi. The second name is by analogy with quectisma, meaning that both are the same commas that reach 5/4 from a different angle, with two mappings converging from opposite ends in 665edo.