Val: Difference between revisions
Vals in non-prime-limit spaces are part of generalizations |
Consolidate discussions on wart notation and others. It makes no sense to separate them. |
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Also note that in practice vals are ''very far'' from just any list of positive integers; rather, they are generally equal to or one off from the lists of integers that correspond to a ''patent val''. | Also note that in practice vals are ''very far'' from just any list of positive integers; rather, they are generally equal to or one off from the lists of integers that correspond to a ''patent val''. | ||
=== | === Generalized patent vals === | ||
{{Main| Generalized patent val }} | {{Main| Generalized patent val }} | ||
{{See also| patent val }} | {{See also| patent val }} | ||
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This works by instead of doing log<sub>2</sub>(''p'') (where ''p'' is prime) we use log<sub>2.01…</sub>(''p'') or something to that effect, where 2.01/1 is our altered version of 2/1. The ''val'' produced by a slight alteration is usually the same, so there are actually continuous ranges where the val produced is the same. | This works by instead of doing log<sub>2</sub>(''p'') (where ''p'' is prime) we use log<sub>2.01…</sub>(''p'') or something to that effect, where 2.01/1 is our altered version of 2/1. The ''val'' produced by a slight alteration is usually the same, so there are actually continuous ranges where the val produced is the same. | ||
For example, let us say we want to interpret [[104edo]] (104-tone equal temperament) as a [[19-limit]] temperament; there is two possible mappings to use for 5; all primes up to and including 19 are sharp except for 5 which is quite flat, which causes a lot of inconsistencies; therefore a more natural val to use than the patent val is using the second-best mapping for 5, as log<sub>2</sub>(5) × 104 = 241.4805 is very close to exactly off anyways, and given the precision of 104edo, using the second-best mapping is very reasonable, as usually the sharpness of prime 5 cancels out with the sharpness of other primes when constructing ratios from them | For example, let us say we want to interpret [[104edo]] (104-tone equal temperament) as a [[19-limit]] temperament; there is two possible mappings to use for 5; all primes up to and including 19 are sharp except for 5 which is quite flat, which causes a lot of inconsistencies; therefore a more natural val to use than the patent val is using the second-best mapping for 5, as log<sub>2</sub>(5) × 104 = 241.4805 is very close to exactly off anyways, and given the precision of 104edo, using the second-best mapping is very reasonable, as usually the sharpness of prime 5 cancels out with the sharpness of other primes when constructing ratios from them. | ||
== Applications == | == Applications == | ||
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If for some strange reason you'd instead like to say that 900 cents is 7/4, then that would be represented by the {{val| 12 19 28 33 }} val (notated 12d), and if you'd like to say that 1100 cents is 7/4, that would be represented by the {{val| 12 19 28 35 }} (12dd) val. | If for some strange reason you'd instead like to say that 900 cents is 7/4, then that would be represented by the {{val| 12 19 28 33 }} val (notated 12d), and if you'd like to say that 1100 cents is 7/4, that would be represented by the {{val| 12 19 28 35 }} (12dd) val. | ||
== | == Shorthand notations == | ||
{{ | If we basically always want to use the patent val except for a slight modification to a second-best mapping for a handful of primes, it will be tedious to specify the full val every time, so the following shorthand notations are developed to address that. | ||
=== Wart notation === | |||
In this notation, we can specify the patent val of ''n''-edo as just ''n'', then we can specify each prime we want to map to the second best approximation by appending a letter, called a ''wart'', after the number: | |||
* adding a means you make the mapping of 2 worse | |||
* adding b means you make the mapping of 3 worse | |||
* adding c means you make the mapping of 5 worse | |||
* adding d means you make the mapping of 7 worse | |||
* etc. | |||
So we can refer to {{val| 17 27 40 }} by "17c" (not to be confused with 17{{cent}} (cents)), where we mnemonically think "a, b, '''c'''; 3rd letter; 3rd prime is 2, 3, '''5'''; there is one 'c' so we make the mapping of prime 5 worse (further from just) once compared to patent". | |||
The general rules: | The general rules: | ||
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In 2022 [[User:Mike Battaglia|Mike Battaglia]] proposed '''SOV notation''' as a way to be explicit about which primes are being affected and in which direction. In 2024 it was further refined by him and [[User:Frostburn|Lumi Pakkanen]] to be more analogous to [[Ups and downs notation]]. | In 2022 [[User:Mike Battaglia|Mike Battaglia]] proposed '''SOV notation''' as a way to be explicit about which primes are being affected and in which direction. In 2024 it was further refined by him and [[User:Frostburn|Lumi Pakkanen]] to be more analogous to [[Ups and downs notation]]. | ||
In this notation, patent vals are notated using the number of divisions followed by square brackets e.g. 17[] for {{val| 17 27 39 }}. To indicate a wider mapping for a prime, it is prefixed with a carret (^) e.g. 17[^5] for {{val| 17 27 40 }}. To indicate a narrower mapping for a prime it is prefixed with a vee (v) e.g. 17[v5] for {{val| 17 27 38 }}. The prefixes stack e.g. 17[^^5] corresponds to {{val| 17 27 41 }}. Multiple modifications are separated by commas (and optionally spaces) e.g. 17[v3, ^5] for {{val| 17 26 40 }}. | |||
To indicate a wider mapping for a prime it is prefixed with a carret (^) e.g. 17[^5] for {{val| 17 27 40 }}. | |||
To indicate a narrower mapping for a prime it is prefixed with a vee (v) e.g. 17[v5] for {{val| 17 27 38 }}. | |||
The prefixes stack e.g. 17[^^5] corresponds to {{val| 17 27 41 }}. | |||
Multiple modifications are separated by commas (and optionally spaces) e.g. 17[v3, ^5] for {{val| 17 26 40 }}. | |||
The interval of equivalence may be prefixed in square brackets e.g. [3]13[] for {{val| 8 13 19 }} (subgroup 2.3.5). | The interval of equivalence may be prefixed in square brackets e.g. [3]13[] for {{val| 8 13 19 }} (subgroup 2.3.5). | ||
The subgroup may be made explicit separated by an "at" sign (@) at the end e.g. 46[]@2.3.7.13/5 for {{val| 46 73 129 63 }} (subgroup 2.3.7.13/5). | The subgroup may be made explicit separated by an "at" sign (@) at the end e.g. 46[]@2.3.7.13/5 for {{val| 46 73 129 63 }} (subgroup 2.3.7.13/5). Formal primes are treated the same way as actual primes e.g. 46[^13/5]@2.3.7.13/5 for {{val| 46 73 129 64 }} (subgroup 2.3.7.13/5) | ||
Formal primes are treated the same way as actual primes e.g. 46[^13/5]@2.3.7.13/5 for {{val| 46 73 129 64 }} (subgroup 2.3.7.13/5) | |||
For patent vals the empty square brackets are optional when using an "at" sign. The subgroup itself is optional if its obvious from context e.g. 12@ for {{val|12 19 28 }} (subgroup 2.3.5). | For patent vals the empty square brackets are optional when using an "at" sign. The subgroup itself is optional if its obvious from context e.g. 12@ for {{val| 12 19 28 }} (subgroup 2.3.5). | ||
The 2022 version used a plus sign (+) in place of the caret and a minus sign (-) in place of the vee. | The 2022 version used a plus sign (+) in place of the caret and a minus sign (-) in place of the vee. [https://sintel.pythonanywhere.com Sintel's temperament calculator] is a notable implementation of this notation. | ||
== Vals vs. mappings == | == Vals vs. mappings == | ||