Mapping to lattice: Difference between revisions
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Many temperaments documented on the wiki are accompanied with a '''mapping to lattice'''. These use the same [[extended bra-ket notation]] as temperament [[ | Many temperaments documented on the wiki are accompanied with a '''mapping to lattice'''. These use the same [[extended bra-ket notation]] as temperament [[mapping]]s but provide quite different information: they give the coordinates of the primes in a tempered lattice. The lattice for which they give coordinates does not necessarily correspond with the mapping otherwise provided. | ||
== Example == | == Example == | ||
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Consider [[keemic]]. Its mapping to lattice is given as {{rket| {{map| 0 0 -1 3 }} {{map| 0 1 1 0 }} }}. We can read this in four vertical slices; the coordinate (0, 0) is for prime 2, (0, 1) is for prime 3, (-1, 1) is for prime 5, and (3, 0) is for prime 7. | Consider [[keemic]]. Its mapping to lattice is given as {{rket| {{map| 0 0 -1 3 }} {{map| 0 1 1 0 }} }}. We can read this in four vertical slices; the coordinate (0, 0) is for prime 2, (0, 1) is for prime 3, (-1, 1) is for prime 5, and (3, 0) is for prime 7. | ||
Note that | Note that keemic is a rank-3 temperament, meaning it has three generators. Or said another way, it has one period and two (other) generators. This corresponds with the fact that it has three generator maps – or rows – in its mapping matrix, which is given as {{rket| {{map| 1 0 0 5 }} {{map| 0 1 0 3 }} {{map| 0 0 1 -3 }} }}. The reason the mapping to lattice has only two rows while the mapping has three rows is because [[octave equivalence]] has been assumed in the lattice. So the first generator, the special one, the period, which in this case is equal to the octave, is not visualized on this lattice; we use one axis for the first generator, and the other axis of the second generator. | ||
The octave equivalence also explains why prime 2 is found at (0, 0). | The octave equivalence also explains why prime 2 is found at (0, 0). | ||
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[[Category:Regular temperament theory]] | [[Category:Regular temperament theory]] | ||
[[Category:Mapping]] | |||
[[Category:Lattice]] | |||