Crawma

Interval information

Ratio	83521/83486
Subgroup monzo	2.13.17.19 [-1 -3 4 -1⟩
Size in cents	0.7256366¢
Name	crawma
Color name	19u17o43u32, nuquadso-atrithu 2nd, Nuquadso-atrithu comma
FJS name	[math]\displaystyle{ \text{m2}^{17,17,17,17}_{13,13,13,19} }[/math]
Special properties	reduced
Tenney norm (log2 nd)	32.6991
Weil norm (log2 max(n, d))	32.6997
Wilson norm (sopfr(nd))	128
Comma size	unnoticeable
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Crawma, known as the crawma, is a 19-limit (more precisely, 2.17/13.19/13 subgroup) unnoticeable comma. It forms the difference between a stack of four 17/13's and a stack of one octave and one 19/13.

Temperaments

Tempering out this comma in the 19-limit leads to the rank-7 crawmic temperament, or in the 2.17/13.19/13 subgroup, the rank-2 crawic temperament generated by a tempered 17/13. 31edo's 12\31 = 464.516¢ is the first generator to tune crawic accurately, with 17/13, 19/13, and 19/17 respectively having errors +0.088¢, +1.079¢, and +0.991¢. The CTE generator of crawic temperament, 464.236¢, is extremely well-approximated by 53\137 = 464.234¢.

Terminology

The name crawma was proposed by groundfault as a more distinctive-sounding crow-themed name for the comma than "cawma". The word craw has an archaic sense 'to caw, to croak, to crow'.

See also

• Unnoticeable comma