2187/1250: Difference between revisions

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| Color name = g<sup>4</sup>7, quadgu 7th
| Color name = g<sup>4</sup>7, quadgu 7th
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'''2187/1250''', the '''tetraptolemaic diminished seventh''' or '''ragismic 5-limit harmonic seventh''', is a [[5-limit]] interval very closely approximating [[7/4]]. It is a [[4375/4374|ragisma]] below 7/4, a [[15625/15552|kleisma]] below the marvel 5-limit harmonic seventh [[225/128]], and [[250/243]] below [[9/5]]. In the [[ragismic]] temperament, it is equated with 7/4.
'''2187/1250''', the '''tetraptolemaic diminished seventh''' or '''ragismic 5-limit harmonic seventh''', is a [[5-limit]] interval very closely approximating [[7/4]]. It can be created by stacking two [[27/25]] and [[3/2]]. It is a [[4375/4374|ragisma]] below 7/4, a [[15625/15552|kleisma]] below the marvel 5-limit harmonic seventh [[225/128]], and [[250/243]] below [[9/5]]. In the [[ragismic]] temperament, it is equated with 7/4.


==Approximation==
==Approximation==

Revision as of 13:29, 15 January 2026

Interval information
Ratio 2187/1250
Factorization 2-1 × 37 × 5-4
Monzo [-1 7 -4
Size in cents 968.4302¢
Names tetraptolemaic diminished seventh,
ragismic 5-limit harmonic seventh
Color name g47, quadgu 7th
FJS name [math]\displaystyle{ \text{d7}_{5,5,5,5} }[/math]
Special properties reduced
Tenney norm (log2 nd) 21.3824
Weil norm (log2 max(n, d)) 22.1895
Wilson norm (sopfr(nd)) 43
Open this interval in xen-calc

2187/1250, the tetraptolemaic diminished seventh or ragismic 5-limit harmonic seventh, is a 5-limit interval very closely approximating 7/4. It can be created by stacking two 27/25 and 3/2. It is a ragisma below 7/4, a kleisma below the marvel 5-limit harmonic seventh 225/128, and 250/243 below 9/5. In the ragismic temperament, it is equated with 7/4.

Approximation

57edo contains a very accurate approximation of 2187/1250 at its 46th step (46\57), which is only 0.009 ¢ flat of 2187/1250.