Period

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The period of a MOS scale is the interval at which the MOS pattern repeats. Another word for the period is the interval of repetition. It is usually the same size as the equave (interval of equivalence) or a fraction thereof. Along with the generator, it is one of the two defining intervals of a MOS. For example:

  • The diatonic scale (LLsLLLs) has period equal to the octave.
  • The diminished scale (sLsLsLsL) has period 1\4, because the MOS pattern sL repeats at every 300 cents.

The same definition applies for a rank-2 temperament, when the temperament is seen as generating a MOS. Every interval of a rank-2 temperament is a sum of some number of the period and some number of the generator of the temperament.