Neutral and interordinal intervals in MOS scales: Difference between revisions
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# Given 1 ≤ ''k'' ≤ a + b − 1, the '''neutral''' ''k''-mosstep or ''k''-step (abbrev. n''k''ms, n''k''s) is the interval exactly halfway between the smaller ''k''-step and the larger ''k''-step of the mos. When the mos is generated by a (perfect) ''k''-step, this may instead be called the '''semiperfect''' ''k''-step (abbrev. sP''k''s), since it is halfway between the perfect and imperfect (either diminished or augmented, depending on whether the generator is bright or dark) ''k''-step. The following ''always'' holds for a given interval class of ''k''-steps between 1-steps and (a + b − 1)-steps, inclusive: | # Given 1 ≤ ''k'' ≤ a + b − 1, the '''neutral''' ''k''-mosstep or ''k''-step (abbrev. n''k''ms, n''k''s) is the interval exactly halfway between the smaller ''k''-step and the larger ''k''-step of the mos. When the mos is generated by a (perfect) ''k''-step, this may instead be called the '''semiperfect''' ''k''-step (abbrev. sP''k''s), since it is halfway between the perfect and imperfect (either diminished or augmented, depending on whether the generator is bright or dark) ''k''-step. The following ''always'' holds for a given interval class of ''k''-steps between 1-steps and (a + b − 1)-steps, inclusive: | ||
#: neutral ''k''-step = smaller ''k''-step + c/2 = larger ''k''-step − c/2, where c = L − s is the [[chroma]] of the mos. | #: neutral ''k''-step = smaller ''k''-step + c/2 = larger ''k''-step − c/2, where c = L − s is the [[chroma]] of the mos. | ||
# Given 1 ≤ ''k'' ≤ a + b − 2, and assuming that the larger ''k''-step < the smaller (''k'' + 1)-step, the '''interordinal''' between ''k''-steps and (''k'' + 1)-steps, denoted ''k''x(''k'' + 1)(m)s or ''k''X(''k'' + 1)(m)s (read "''k'' cross (''k'' + 1) (mos)step" or "''k'' inter (''k'' + 1) (mos)step"), is the interval exactly halfway between the larger ''k''-step and the smaller (''k'' + 1)-step. | # Given 1 ≤ ''k'' ≤ a + b − 2, and assuming that the larger ''k''-step < the smaller (''k'' + 1)-step, the '''interordinal''' between ''k''-steps and (''k'' + 1)-steps, denoted ''k''x(''k'' + 1)(m)s or ''k''X(''k'' + 1)(m)s (read "''k'' cross (''k'' + 1) (mos)step" or "''k'' inter (''k'' + 1) (mos)step"), is the interval exactly halfway between the larger ''k''-step and the smaller (''k'' + 1)-step. | ||
#: If the smaller (''k'' + 1)-step is ''strictly larger'' than the larger ''k''-step in ''basic'' aLbs, ''k''X(''k'' + 1) is called a '''proper interordinal'''. The following holds for any proper interordinal interval ''k''-inter-(''k'' + 1)-step: | |||
#: ''k''-inter-(''k'' + 1)-step = larger ''k''-step + s/2 = smaller (''k'' + 1)-step − s/2. | #: ''k''-inter-(''k'' + 1)-step = larger ''k''-step + s/2 = smaller (''k'' + 1)-step − s/2. | ||
Neutral ''k''-steps generalize neutral interval categories based on the diatonic mos, which are: | Neutral ''k''-steps generalize neutral interval categories based on the diatonic mos, which are: | ||