28/15
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Ratio
28/15
Factorization
22 × 3-1 × 5-1 × 7
Monzo
[2 -1 -1 1⟩
Size in cents
1080.557¢
Name
septimal grave major seventh
Color name
zg8, zogu octave
FJS name
[math]\text{d8}^{7}_{5}[/math]
Special properties
reduced
Tenney height (log2 nd)
8.71425
Weil height (log2 max(n, d))
9.61471
Wilson height (sopfr(nd))
19
Harmonic entropy
(Shannon, [math]\sqrt{nd}[/math])
~4.22382 bits
[sound info]
open this interval in xen-calc
| Interval information |
(Shannon, [math]\sqrt{nd}[/math])
[sound info]
28/15 is a 7-limit just intonation interval of about 1080.6 cents. It is well approximated by 10edo (9\10).
Terminology
Despite being approximated by the major seventh in systems like septimal meantone, and even being called the septimal grave major seventh by some musicians, 28/15 is a diminished octave in just intonation notation systems such as Sagittal notation, Helmholtz-Ellis notation and the Functional Just System, viewed as the Pythagorean diminished octave (4096/2187) altered by 5120/5103.