Stacking: Difference between revisions

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In the context of tuning theory, '''stacking''' is the group operation of a [[free abelian group]] of [[interval]]<nowiki/>s. It corresponds to multiplying or dividing the pitch [[ratio]]<nowiki/>s corresponding to the intervals, or adding or subtracting their [[cent]] values. In a rank-n [[temperament]], there are n [[Generator|generators]] which can be stacked to produce any interval in the group.  
In the context of tuning theory, '''stacking''' is the group operation of a [[free abelian group]] of [[interval]]s. It corresponds to multiplying or dividing the pitch [[ratio]]s corresponding to the intervals, or adding or subtracting their [[cent]] values. Depending on context, [[octave reduction]] (or the analogue for other [[equave]]s) is sometimes assumed. In a [[rank]]-''n'' [[temperament]], there are ''n'' [[generator]]s which can be stacked to produce any interval in the group.  


A simple example of stacking can be seen in [[Pythagorean]] tuning, or 3-limit JI, a [[rank-2 temperament]] that [[Tempering out|tempers out]] no c[[Comma|ommas]], which is generated by stacking (multiplying or dividing by) the primes 3 and 2. For example, the interval [[531441/524288]] can be produced by multiplying by 3 twelve times, and then dividing by 2 nineteen times. Its descending counterpart, 524288/531441, can be produced by multiplying by 2 nineteen times, then dividing by 3 twelve times. In terms of cent values, this corresponds to adding or subtracting steps of 1200 cents or log2(3)*1200 ≈ 1901.955 cents.
A simple example of stacking can be seen in [[Pythagorean]] tuning, or [[3-limit]] [[JI]], a [[rank-2 temperament]] that [[Tempering out|tempers out]] no [[comma]]s, which is generated by stacking (multiplying or dividing by) the primes 3 and 2. For example, the interval [[531441/524288]] can be produced by multiplying by 3 twelve times, and then dividing by 2 nineteen times. Its descending counterpart, 524288/531441, can be produced by multiplying by 2 nineteen times, then dividing by 3 twelve times. In terms of cent values, this corresponds to adding or subtracting steps of 1200 cents or log2(3)*1200 ≈ 1901.955 cents.


Stacking is used to explain [[Regular temperament|regular temperaments]], which are often described in terms of stacking an interval to produce another interval.
Stacking is used to explain [[regular temperament]]s, which are often described in terms of stacking multiple instances of a single interval to produce another interval, and commas, which are describable as the difference between a stack of one interval and a stack of a different interval.
 
[[Category:Method]]