Harmonic limit: Difference between revisions
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A positive rational number ''q'' belongs to the '''''p''-limit''', called the '''''p'' harmonic''' or '''prime limit''', for a given [[prime number]] ''p'' if and only if it can be factored into primes (with positive or negative integer exponents) of size less than or equal to ''p''. For any prime number ''p'', the set of all rational numbers in the ''p''-limit defines a [[Wikipedia: Free_abelian_group|finitely generated free abelian group]]. The rank of this group is equal to π (''p''), the number of prime numbers less than or equal to ''p''. Hence, for example, the rank of the [[7-limit]] is 4, as it is generated by 2, 3, 5 and 7. Another way to express the ''p''-limit is that it consists of the ratios of [[Wikipedia: Smooth number|''p''-smooth numbers]], where a ''p''-smooth number is an integer with prime factors no larger than ''p''. | A positive rational number ''q'' belongs to the '''''p''-limit''', called the '''''p'' harmonic''' or '''prime limit''', for a given [[prime number]] ''p'' if and only if it can be factored into primes (with positive or negative integer exponents) of size less than or equal to ''p''. For any prime number ''p'', the set of all rational numbers in the ''p''-limit defines a [[Wikipedia: Free_abelian_group|finitely generated free abelian group]]. The rank of this group is equal to π (''p''), the number of prime numbers less than or equal to ''p''. Hence, for example, the rank of the [[7-limit]] is 4, as it is generated by 2, 3, 5 and 7. Another way to express the ''p''-limit is that it consists of the ratios of [[Wikipedia: Smooth number|''p''-smooth numbers]], where a ''p''-smooth number is an integer with prime factors no larger than ''p''. | ||
== | == Examples of p-limits == | ||
With increasing limits, the tonal space becomes more dense. | With increasing limits, the tonal space becomes more dense. | ||
* [[2-limit]] contains only multiples of the [[ | * [[2-limit]] contains only multiples of the [[octave]] (2/1), see [[1edo]] | ||
* [[3-limit]] contains [[3/2]], the [[just perfect fifth]] | * [[3-limit]] contains [[3/2]], the [[just perfect fifth]] | ||
* [[5-limit]] contains [[5/4]], the perfect major third | * [[5-limit]] contains [[5/4]], the perfect major third | ||
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* [[29-limit]] | * [[29-limit]] | ||
* [[31-limit]] | * [[31-limit]] | ||
* [[47-limit]] | * [[47-limit]] | ||
* [[61-limit]] | * [[61-limit]] | ||