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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]\text{45d}{-31}^{5}[/math]
Special properties reduced
Tenney height (log2 nd) 1000
Weil height (log2 max(n, d)) 1000
Wilson height (sopfr (nd)) 1947
Harmonic entropy
(Shannon, [math]\sqrt{n\cdot d}[/math])
~2.39764 bits
Comma size unnoticeable
open this interval in xen-calc

Counterquectisma, alternately deltapion comma, is an unnoticeable 5-limit comma.


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.


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.