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Interval information
Ratio 33/25
Factorization 3 × 5-2 × 11
Monzo [0 1 -2 0 1
Size in cents 480.64552¢
Names ptolemismic fourth,
undecimal imperfect fourth,
5edo-esque fourth
Color name 1ogg4, logugu 4th
FJS name [math]\text{d4}^{11}_{5,5}[/math]
Special properties reduced
Tenney height (log2 nd) 9.68825
Weil height (log2 max(n, d)) 10.0888
Wilson height (sopfr (nd)) 24
Harmonic entropy
(Shannon, [math]\sqrt{n\cdot d}[/math])
~4.46726 bits

[sound info]
open this interval in xen-calc

33/25, the ptolemismic fourth, the undecimal imperfect fourth or the 5edo-esque fourth, is an 11-limit interval. It is flat of 4/3, the perfect fourth, by 100/99, the ptolemisma, hence the name. It is also sharp of 21/16, the subfourth, by 176/175, the valinorsma. Being 11/8 diminished by 25/24, it is technically a semidiminished fourth aka paraminor fourth.


Measuring about 480.6 ¢, 33/25 is very well approximated by 5edo and its supersets.

See also