Distributional evenness: Difference between revisions
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Formally, consider an ''r''-ary periodic scale ''S'' with length ''n'' (i.e. ''S''(''kn'') = ''kP'' where ''P'' is the period), with step sizes ''x''<sub>1</sub>, ..., ''x''<sub>''r''</sub>, i.e. such that Δ''S''(''i'') := ''S''(''i''+1) − ''S''(''i'') ∈ {''x''<sub>1</sub>, ..., ''x''<sub>''r''</sub>} ∀''i'' ∈ '''Z'''. For each ''i'' ∈ {1, ..., ''r''}, define ''T''<sub>''i''</sub> = (Δ''S'')<sup>−1</sup>(''x''<sub>''i''</sub>), naturally viewed as a subset of '''Z'''/''n'''''Z'''. The scale ''S'' is ''distributionally even'' if for every ''i'' ∈ {1, ..., ''r''}, ''T''<sub>''i''</sub> is a rotation of the [[maximally even]] MOS of |''T''<sub>i</sub>| notes in '''Z'''/''n'''''Z'''. (For the original definition of DE, simply set ''r'' = 2.) | Formally, consider an ''r''-ary periodic scale ''S'' with length ''n'' (i.e. ''S''(''kn'') = ''kP'' where ''P'' is the period), with step sizes ''x''<sub>1</sub>, ..., ''x''<sub>''r''</sub>, i.e. such that Δ''S''(''i'') := ''S''(''i''+1) − ''S''(''i'') ∈ {''x''<sub>1</sub>, ..., ''x''<sub>''r''</sub>} ∀''i'' ∈ '''Z'''. For each ''i'' ∈ {1, ..., ''r''}, define ''T''<sub>''i''</sub> = (Δ''S'')<sup>−1</sup>(''x''<sub>''i''</sub>), naturally viewed as a subset of '''Z'''/''n'''''Z'''. The scale ''S'' is ''distributionally even'' if for every ''i'' ∈ {1, ..., ''r''}, ''T''<sub>''i''</sub> is a rotation of the [[maximally even]] MOS of |''T''<sub>i</sub>| notes in '''Z'''/''n'''''Z'''. (For the original definition of DE, simply set ''r'' = 2.) | ||
Using this definition, an ''r''-ary scale word in ''x''<sub>1</sub>, ..., ''x''<sub>''r''</sub> is DE if and only if for every ''i'' ∈ {1, ..., ''r''}, the binary scale obtained by equating all step sizes except ''x''<sub>i</sub> is DE. | Using this definition, an ''r''-ary scale word in ''x''<sub>1</sub>, ..., ''x''<sub>''r''</sub> is DE if and only if for every ''i'' ∈ {1, ..., ''r''}, the binary scale obtained by equating all step sizes except ''x''<sub>''i''</sub> is DE. | ||
[[Category:Terms]] | [[Category:Terms]] | ||
[[Category:Scale]] | [[Category:Scale]] |