729/640: Difference between revisions

From Xenharmonic Wiki
Jump to navigation Jump to search
Aura (talk | contribs)
No edit summary
Sectioning
Line 4: Line 4:
}}
}}


'''729/640''', the '''retroptolemaic whole tone''', is the interval that results from stacking [[16/15]] (classical diatonic semitone) and [[2187/2048]] (Pythagorean apotome), or [[27/25]] (large limma) and [[135/128]] (major limma). It is equal to [[9/8]] raised by a [[syntonic comma]], about 225.4 [[cent]]s in size, and well approximated by three steps of [[16edo]], and 16 of them exceed three octaves by the comma (729/640)<sup>16</sup>/2<sup>3</sup> = 3<sup>96</sup>/(2<sup>115</sup>×5<sup>16</sup>) = {{monzo|-115 96 -16}} (lela-quadquadgu negative 6th, ~6.66 cents).  In addition, this interval differs from [[256/225]] (Neapolitan diminished third) by the [[schisma]].
'''729/640''', the '''retroptolemaic whole tone''', is the interval that results from stacking [[16/15]] (classical diatonic semitone) and [[2187/2048]] (Pythagorean apotome), or [[27/25]] (large limma) and [[135/128]] (major limma). It is equal to [[9/8]] raised by a [[syntonic comma]], about 225.4 [[cent]]s in size.
 
== Approximation ==
This interval is well approximated by three steps of [[16edo]], and 16 of them exceed three octaves by the comma (729/640)<sup>16</sup>/2<sup>3</sup> = 3<sup>96</sup>/(2<sup>115</sup>×5<sup>16</sup>) = {{monzo|-115 96 -16}} (lela-quadquadgu negative 6th, ~6.66 cents).  In addition, this interval differs from [[256/225]] (Neapolitan diminished third) by the [[schisma]].


== See also ==
== See also ==

Revision as of 11:19, 2 January 2025

Interval information
Ratio 729/640
Factorization 2-7 × 36 × 5-1
Monzo [-7 6 -1
Size in cents 225.4163¢
Names acute whole tone,
retroptolemaic whole tone
Color name Lg2, lagu 2nd
FJS name [math]\displaystyle{ \text{M2}_{5} }[/math]
Special properties reduced
Tenney norm (log2 nd) 18.8317
Weil norm (log2 max(n, d)) 19.0196
Wilson norm (sopfr(nd)) 37
Open this interval in xen-calc

729/640, the retroptolemaic whole tone, is the interval that results from stacking 16/15 (classical diatonic semitone) and 2187/2048 (Pythagorean apotome), or 27/25 (large limma) and 135/128 (major limma). It is equal to 9/8 raised by a syntonic comma, about 225.4 cents in size.

Approximation

This interval is well approximated by three steps of 16edo, and 16 of them exceed three octaves by the comma (729/640)16/23 = 396/(2115×516) = [-115 96 -16 (lela-quadquadgu negative 6th, ~6.66 cents). In addition, this interval differs from 256/225 (Neapolitan diminished third) by the schisma.

See also