Delta-rational chord: Difference between revisions
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== Notation == | == Notation == | ||
=== Linear signature === | === Linear signature === | ||
Some, but not all, delta-rational chords can be described with | Some, but not all, delta-rational chords can be described with a ''linear signature'' or ''lis'' which has integer ratios, i.e. a list of increments between successive notes, their ratios showing the simple rational relationships and ? for no relationship (or no obvious one). For example saying that a tetrad is "+1 +? +1" means the first two notes and the last two notes have almost equal frequency difference (thus the ratio between the differences is 1/1), but the middle two notes are not in any simple relationship with the two outer dyads. The example 13edo chord is approximately +1 +? +1. Note that this notation only considers dyads between successive notes, what we call ''increments''. | ||
If you have some sets of increments related to each other but not to other sets of increments, you could write the related sets with variables a, b, c or use one fewer letter by writing one set with positive integers without variables: an +a +b +a +b chord can also be written +1 +a +1 +a. | If you have some sets of increments related to each other but not to other sets of increments, you could write the related sets with variables a, b, c or use one fewer letter by writing one set with positive integers without variables: an +a +b +a +b chord can also be written +1 +a +1 +a. | ||