User:CompactStar/Ordinal interval notation: Difference between revisions

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m CompactStar moved page User:CompactStar/Binary search notation to User:CompactStar/Indexed interval notation over redirect: Yeah I really can't make up my mind on which variant
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'''Binary search notation''' is a notation for [[just intonation]] devised by [[User:CompactStar|CompactStar]].
Indexed interval notation is a notation for [[just intonation]] in which all intervals are represented by a normal interval classification combined with a ordinal number or index. An index of 1 is used for the simplest interval in an interval class (such as [[6/5]] for minor thirds), an index of 2 is used for the second-simplest, an index of 3 is used for the third-simplest, and so on.


Intervals are represented by a conventional interval category with a stack of lefts and rights (abbreviated as L and R) added before. To get the category of an interval, multiply the categories of the prime harmonics which it factors into, which are predefined as follows:
== Definition ==
To get the classification for an interval, multiply the interval classes of the prime harmonics which it factors into, which are predefined as follows:
{|class="wikitable"
{|class="wikitable"
|-
|-
!Prime harmonic
!Prime harmonic
!colspan="3"|Notation
!colspan="2"|Interval classification
|-
|-
|[[2/1]]
|[[2/1]]
|P8
|P8
|perfect octave
|perfect octave
|C
|-
|-
|[[3/2]]
|[[3/2]]
|P5
|P5
|perfect 5th
|perfect fifth
|G
|-
|-
|[[5/4]]
|[[5/4]]
|M3
|M3
|major 3rd
|major third
|E
|-
|-
|[[7/4]]
|[[7/4]]
|m7
|m7
|minor 7th
|minor seventh
|Bb
|-
|-
|[[11/8]]
|[[11/8]]
|P4
|P4
|perfect 4th
|perfect fourth
|F
|-
|-
|[[13/8]]
|[[13/8]]
|m6
|m6
|minor 6th
|minor sixth
|Ab
|-
|-
|[[17/16]]
|[[17/16]]
|m2
|m2
|minor 2nd
|minor second
|Db
|-
|-
|[[19/16]]
|[[19/16]]
|m3
|m3
|minor 3rd
|minor third
|Eb
|-
|-
|[[23/16]]
|[[23/16]]
|A4
|A4
|augmented 4th
|augmented fourth
|F#
|-
|-
|[[29/16]]
|[[29/16]]
|m7
|m7
|minor 7th
|minor seventh
|Bb
|-
|-
|[[31/16]]
|[[31/16]]
|P8
|P8
|perfect octave
|perfect octave
|C
|-
|-
|[[37/32]]
|
|M2
|major 2nd
|D
|-
|[[41/32]]
|M3
|major 3rd
|E
|-
|[[43/32]]
|P4
|perfect 4th
|F
|-
|[[47/32]]
|P5
|perfect 5th
|G
|-
|[[53/32]]
|M6
|major 6th
|A
|-
|[[61/32]]
|M7
|major 7th
|B
|-
|[[67/64]]
|m2
|minor 2nd
|Db
|-
|[[71/64]]
|M2
|major 2nd
|D
|-
|[[73/64]]
|M2
|major 2nd
|D
|-
|[[79/64]]
|M3
|major 3rd
|E
|-
|[[83/64]]
|P4
|perfect 4th
|F
|-
|[[89/64]]
|d5
|diminished 5th
|Gb
|-
|[[97/64]]
|P5
|perfect 5th
|G
|}
|}
The simplest (with respect to [[Tenney height]]) interval inside a category does not use any lefts or rights (or is "central"), for example [[6/5]] for minor 3rd. The simplest interval which is flatter than the central interval is left ([[7/6]] for minor 3rd), and the simplest interval which is sharper is right ([[11/9]] for minor 3rd). Then the simplest interval which is flatter than the left is leftleft, the simplest interval between left and central is leftright , the simplest interval which is between central and right is rightleft, and the simplest interval which is sharper than right is rightright. This process of bisection with lefts/rights can be continued infinitely to name all just intervals that are in a category. Interval arithmetic is preserved (e.g. M2 * M2 is always M3), however the lefts and rights do not combine like accidentals do.

Revision as of 08:49, 30 December 2023

Indexed interval notation is a notation for just intonation in which all intervals are represented by a normal interval classification combined with a ordinal number or index. An index of 1 is used for the simplest interval in an interval class (such as 6/5 for minor thirds), an index of 2 is used for the second-simplest, an index of 3 is used for the third-simplest, and so on.

Definition

To get the classification for an interval, multiply the interval classes of the prime harmonics which it factors into, which are predefined as follows:

Prime harmonic Interval classification
2/1 P8 perfect octave
3/2 P5 perfect fifth
5/4 M3 major third
7/4 m7 minor seventh
11/8 P4 perfect fourth
13/8 m6 minor sixth
17/16 m2 minor second
19/16 m3 minor third
23/16 A4 augmented fourth
29/16 m7 minor seventh
31/16 P8 perfect octave
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