As "Modal Color Theory" (pp. 31ff.) describes, it can be useful to know whether two colors are adjacent to each other in the MCT space. That is, can one scalar color be continuously modified until it becomes the other, without crossing through any third color? For instance, the 5-limit just diatonic scale is a two-dimensional color that is adjacent to the 1-d line of meantone diatonic scales. This means, in some sense, that the meantone structure is a good approximation of the 5-limit just structure.
comparesignvecs(signvecX, signvecY)Integer: 0 if the sign vectors represent the same color,
1 if they are adjacent, and -1 if they are neither adjacent nor
identical.
A pair of sign vectors to be compared. Note that these must be sign vectors, not scales themselves.
meantone_major_sv <- signvector(c(0, 2, 4, 5, 7, 9, 11))
meantone_dorian_sv <- signvector(c(0, 2, 3, 5, 7, 9, 10))
just_major <- j(dia)
just_dorian <- sim(just_major)[,2]
just_major_sv <- signvector(just_major)
just_dorian_sv <- signvector(just_dorian)
comparesignvecs(meantone_major_sv, just_major_sv)
comparesignvecs(meantone_dorian_sv, just_major_sv)
comparesignvecs(meantone_dorian_sv, just_dorian_sv)
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