28/25: Difference between revisions

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55edo directly approximates this very closely, but maps it inconsistently
 
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'''28/25''', the '''(septimal) middle whole tone''', is the interval between [[5/4]] and [[7/5]], and is intermediate in size between [[10/9]], of which it is [[126/125]] sharp, and [[9/8]], of which it is [[225/224]] flat. It's actually the [[mediant]] of [[19/17]] and [[9/8]]. A [[meantone]] where the tone is tuned to be exactly 28/25 has a fifth of size 2√14/5, or 698.099{{cent}}, which is closely approximated by [[55edo]].
'''28/25''', the '''(septimal) middle whole tone''', is the interval between [[5/4]] and [[7/5]], and is intermediate in size between [[10/9]], of which it is [[126/125]] sharp, and [[9/8]], of which it is [[225/224]] flat. It's actually the [[mediant]] of [[19/17]] and [[9/8]]. A [[meantone]] where the tone is tuned to be exactly 28/25 has a fifth of size 2√14/5, or 698.099{{cent}}, which is closely approximated by [[55edo]] (however, 55edo in its patent val maps this interval inconsistently to 8\55 instead of 9\55; 55d is required for proper mapping).


== Approximation ==
{{Interval edo approximation|28/25}}
== See also ==
== See also ==
* [[25/14]] – its [[octave complement]]
* [[25/14]] – its [[octave complement]]

Latest revision as of 02:27, 2 June 2026

Interval information
Ratio 28/25
Factorization 22 × 5-2 × 7
Monzo [2 0 -2 1
Size in cents 196.1985¢
Names (septimal) middle major second,
(septimal) middle whole tone
Color name zgg3, zogugu 3rd
FJS name [math]\displaystyle{ \text{d3}^{7}_{5,5} }[/math]
Special properties reduced
Tenney norm (log2 nd) 9.45121
Weil norm (log2 max(n, d)) 9.61471
Wilson norm (sopfr(nd)) 21

[sound info]
Open this interval in xen-calc

28/25, the (septimal) middle whole tone, is the interval between 5/4 and 7/5, and is intermediate in size between 10/9, of which it is 126/125 sharp, and 9/8, of which it is 225/224 flat. It's actually the mediant of 19/17 and 9/8. A meantone where the tone is tuned to be exactly 28/25 has a fifth of size 2√14/5, or 698.099 ¢, which is closely approximated by 55edo (however, 55edo in its patent val maps this interval inconsistently to 8\55 instead of 9\55; 55d is required for proper mapping).

Approximation

Edo approximations for 28/25 (196.20 ¢)
≤ 80edo, relative error ≤ 10%
Edo Step size Cents (¢) Absolute error (¢) Relative error (%)
6 1\6 200.00 +3.80 +1.90
12 2\12 200.00 +3.80 +3.80
18 3\18 200.00 +3.80 +5.70
24 4\24 200.00 +3.80 +7.60
25 4\25 192.00 -4.20 -8.75
30 5\30 200.00 +3.80 +9.50
31 5\31 193.55 -2.65 -6.85
37 6\37 194.59 -1.60 -4.95
43 7\43 195.35 -0.85 -3.04
49 8\49 195.92 -0.28 -1.14
55 9\55 196.36 +0.17 +0.76
61 10\61 196.72 +0.52 +2.66
67 11\67 197.01 +0.82 +4.56
73 12\73 197.26 +1.06 +6.46
74 12\74 194.59 -1.60 -9.89
79 13\79 197.47 +1.27 +8.36
80 13\80 195.00 -1.20 -7.99

See also