Octave complement: Difference between revisions

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The '''octave complement''' or '''inverse interval''' of an [[interval]] is its interval distance from the [[octave]]. The '''octave complement''' can be seen as a binary symmetric relation over intervals. The concept important in musical practice and most musical theories. Its use is typically restricted to [[octave-reduced]] intervals (including the octave).
{{Wikipedia|Complement (music)}}
{{Wikipedia|Inversion (music) #Intervals}}
The '''octave complement''' or '''inverse interval''' of an [[interval]] is its difference with the [[octave]]. It can be seen as a binary symmetric relation over intervals. The concept is important in musical practice and most musical theories. Its use is typically restricted to [[octave-reduced]] intervals (including the octave).
 
The octave complement is often simply called '''complement''' in the context of octave-[[equivalent]] scales, but the broader concept of ''complement'' can also apply to other intervals, such as the [[fifth complement]], the [[fourth complement]] and the [[tritave complement]].


== Calculation ==
== Calculation ==
Depending on the interval representation (name, ratio, monzo, edo steps, cents), it's more or less easy to retrieve the complementary interval from a given interval.
Depending on the interval representation (name, [[ratio]], [[monzo]], [[edo]] steps, [[cent]]s), it's more or less easy to retrieve the complementary interval from a given interval.


=== Classical interval names ===
=== Classical interval names ===
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=== Monzo ===
=== Monzo ===
Intervals represented as [[Monzos]] can be transformed into their octave complement by inverting all arguments and increasing the 2-argument.
Intervals represented as monzos can be transformed into their octave complement by inverting all arguments and increasing the 2-argument.


; Examples
; Examples
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=== Edo steps ===
=== Edo steps ===
Octave-complement intervals represented as ''s\n'' meaning ''s'' steps of ''n''-EDO follow this relation <code>s1 + s2 = n</code>. For given s and n, the unknown x can be calculated by the formula <code>x := n-s</code>.
Octave-complement intervals represented as ''s''\''n'' meaning ''s'' steps of ''n''-EDO follow this relation <code>s1 + s2 = n</code>. For given ''s'' and ''n'', the unknown ''x'' can be calculated by the formula <code>x := n -s</code>.


; Examples
; Examples
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=== Cents ===
=== Cents ===
Octave-complement intervals represented as ''s&cent;'' follow this relation <code>s1 + s2 = 1200</code>. For given s, the unknown x can be calculated by the formula <code>x := 1200-s</code>.
Octave-complement intervals represented as ''s''¢ follow this relation <code>s1 + s2 = 1200</code>. For given s, the unknown x can be calculated by the formula <code>x := 1200 - s</code>.


; Examples
; Examples
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== See also ==
== See also ==
* [[Ratio math]]


* [[Fifth complement]]
[[Category:Terms]]
* [[Octave reduction]]
* [https://en.wikipedia.org/wiki/Inversion_(music)#Intervals Inversion (music) &#45; Wikipedia #Intervals]
* [[Tritave complement]] -- the analogue for [[tritave|tritave (3/1)]]
 
[[Category:Term]]
[[Category:Theory]]
[[Category:Interval]]
[[Category:Interval]]
[[Category:Octave]]
[[Category:Octave]]
[[Category:Method]]
[[Category:Method]]