640/637

Interval information

Ratio	640/637
Factorization	27 × 5 × 7-2 × 13-1
Monzo	[7 0 1 -2 0 -1⟩
Size in cents	8.134239¢
Name	huntma
Color name	3urry-2, thururuyo negative 2nd, Thururuyo comma
FJS name	[math]\displaystyle{ \text{d}{-2}^{5}_{7,7,13} }[/math]
Special properties	reduced
Tenney norm (log2 nd)	18.6371
Weil norm (log2 max(n, d))	18.6439
Wilson norm (sopfr(nd))	46
Comma size	small
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640/637, the huntma, is a [[small] comma|small] 13-limit comma. It is the amount by which two 8/7's exceed 13/10. By tempering it out is defined the huntmic temperament, which enables the huntmic chords.

It can be expressed in terms of other commas in a number of ways, but three notable ways that correspond to a product or ratio of two S-commas are noted here:

• S15⋅S64 = (225/224)⋅(4096/4095)
• S8/S9⋅S27 = (5120/5103)⋅(729/728)
• S8/(S13⋅S14) = (64/63)/(91/90)