18/17

Interval information

Ratio	18/17
Subgroup monzo	2.3.17 [1 2 -1⟩
Size in cents	98.95459¢
Name	small septendecimal semitone
Color name	17u1, su unison
FJS name	[math]\displaystyle{ \text{A1}_{17} }[/math]
Special properties	superparticular, reduced
Tenney height (log2 nd)	8.25739
Weil height (log2 max(n, d))	8.33985
Wilson height (sopfr(nd))	25
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In 17-limit just intonation, 18/17 is the small septendecimal semitone of about 99¢. It is very close to 12edo's "half step" of 100¢, and fairly close to the "large septendecimal semitone" of 17/16 (~105¢).

There exists a disagreement in different notation systems on whether 18/17 should be notated as a diatonic semitone or a chromatic semitone. In the Functional Just System, it is a chromatic semitone, whereas in Helmholtz-Ellis notation, it is a diatonic semitone.

See also

• 17/9 – its octave complement
• 17/12 – its fifth complement
• Gallery of just intervals
• List of superparticular intervals
• AS18/17 - its ambitonal sequence