405/392

405/392, the greenwoodma, is a medium 7-limit comma. It is the difference between 8/5 and a stack of two 9/7's. In terms of commas, it is the product of the syntonic comma (81/80) and the jubilisma (50/49).

Interval information

Ratio	405/392
Factorization	2-3 × 34 × 5 × 7-2
Monzo	[-3 4 1 -2⟩
Size in cents	56.4819 ¢
Names	greenwoodma, smaller breedsmic half-apotome
Color name	rry-2, ruruyo negative 2nd
FJS name	[math]\displaystyle{ \text{d}{-2}^{5}_{7,7} }[/math]
Special properties	reduced
Tenney norm (log2 nd)	17.2765
Weil norm (log2 max(n, d))	17.3236
Wilson norm (sopfr(nd))	37
Comma size	medium
Open this interval in xen-calc

In the 11-limit, it factors into simpler commas as (45/44)⋅(99/98).

Temperaments

Tempering out this comma leads to the rank-3 greenwoodmic temperament. This temperament splits a ~5/2 in two, each representing ~14/9. See Greenwoodmic temperaments for a collection of rank-2 temperaments where it is tempered out.

Tempering out instead 2401/2400 equates this with 1323/1280 and sets both equal to sqrt(2187/2048).

Notation

Sagittal notation

In the Sagittal system, the downward version of this comma (possibly tempered) is represented by the sagittal  and is called the 49/5 medium diesis, or 49/5M for short, because the simplest interval it notates is 49/5 = 7×7/5 (equiv. 49/40), as for example in C-E⁠ ⁠. The upward version is called 5/49M or 49/5M up and is represented by .