User:Eliora/Concoctic scale: Difference between revisions
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The length of a maximum evenness scale's generator can be determined through a '''modular multiplicative inverse''' of the note amount and the tuning size<ref>https://individual.utoronto.ca/kalendis/leap/index.htm</ref>: | The length of a maximum evenness scale's generator can be determined through a '''modular multiplicative inverse''' of the note amount and the tuning size<ref>https://individual.utoronto.ca/kalendis/leap/index.htm</ref>: | ||
<math>ax \equiv 1 \mod N</math>, | <math>ax \equiv 1\mod N</math>, | ||
where N is the period, and a is the note count. Therefore, a concoctic scale is defined for a given N: | where N is the period, and a is the note count. Therefore, a concoctic scale is defined for a given N: | ||
<math>aa \equiv 1 \mod N</math>, | <math>aa \equiv 1\mod N</math>, | ||
which simply becomes | which simply becomes | ||
<math>a^2 \equiv 1 \mod N</math>. | <math>a^2 \equiv 1\mod N</math>. | ||
There are also paraconcoctic scales, or chroma-negative concoctic scales. The formula for such a scale is | |||
<math>a^2 \equiv -1 \mod N</math> | <math>a^2 \equiv -1\mod N</math>. | ||
Since octave-inverting the MOS generator has no impact on the scale, paraconcoctic scales are identical to their usual, orthoconcoctic counterparts. However, the difference is pronounced in keyboard making - in terms of chroma direction, the white keys' generator will be the amount of black keys and vice versa. | |||
=== Example === | |||
12edo keyboard layout predominantly in use in the world today features 7 white keys and 5 black keys. The diatonic scale of 7 keys is obtained by stacking the generator, 7\12 fifth 7 times. Likewise, the pentatonic of black keys is obtained by stacking it 5 times. | |||
== List == | == List == | ||