Consistency: Difference between revisions
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Examples on consistency vs. unique consistency: In [[12edo]] the [[7-odd-limit]] intervals 6/5 and 7/6 are both consistently mapped to 3 steps, and although 12edo is consistent up to the [[9-odd-limit]], it is uniquely consistent only up to the [[5-odd-limit]]. Another example or non-unique consistency is given by the intervals [[14/13]] and [[13/12]] in [[72edo]] where they are both mapped to 8 steps. Although 72edo is consistent up to the [[17-odd-limit]], it is uniquely consistent only up to the [[11-odd-limit]]. | Examples on consistency vs. unique consistency: In [[12edo]] the [[7-odd-limit]] intervals 6/5 and 7/6 are both consistently mapped to 3 steps, and although 12edo is consistent up to the [[9-odd-limit]], it is uniquely consistent only up to the [[5-odd-limit]]. Another example or non-unique consistency is given by the intervals [[14/13]] and [[13/12]] in [[72edo]] where they are both mapped to 8 steps. Although 72edo is consistent up to the [[17-odd-limit]], it is uniquely consistent only up to the [[11-odd-limit]]. | ||
== Consistency to distance ''d'' == | == Consistency to distance ''d'' == | ||
Non-technically, a chord is '''consistent to distance''' ''d'' in an edo, if the chord is consistent and you can "walk away" up to distance ''d'' from the chord consistently. So an approximation consistent to some reasonable distance would play more nicely in a regular temperament-style [[subgroup]] context. | Non-technically, a chord is '''consistent to distance''' ''d'' in an edo, if the chord is consistent and you can "walk away" up to distance ''d'' from the chord consistently. So an approximation consistent to some reasonable distance would play more nicely in a regular temperament-style [[subgroup]] context. "Consistent to distance 0" is equivalent to "consistent". | ||
For example, 4:5:6:7 is consistent to distance 2 in [[31edo]]. However, 4:5:6:7:11 is only consistent to distance 0 because 11/5 is mapped too inaccurately (rel error 26.2%). This shows that 31edo is especially strong in the 2.3.5.7 subgroup and weaker in 2.3.5.7.11. | For example, 4:5:6:7 is consistent to distance 2 in [[31edo]]. However, 4:5:6:7:11 is only consistent to distance 0 because 11/5 is mapped too inaccurately (rel error 26.2%). This shows that 31edo is especially strong in the 2.3.5.7 subgroup and weaker in 2.3.5.7.11. | ||
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# every instance of an interval in C is mapped to the same size in C', and | # every instance of an interval in C is mapped to the same size in C', and | ||
# no interval within ''C' '' has [[relative error]] 1/(2(''d''+1)) or more. | # no interval within ''C' '' has [[relative error]] 1/(2(''d''+1)) or more. | ||
(The 1/(2(''m''+1)) threshold is meant to allow stacking ''d'' dyads that occur in the chord without having the sum of the dyads have over 50% relative error.) | (The 1/(2(''m''+1)) threshold is meant to allow stacking ''d'' dyads that occur in the chord without having the sum of the dyads have over 50% relative error.) | ||