「パテントヴァル」の版間の差分
Dummy index (トーク | 投稿記録) 編集の要約なし |
Dummy index (トーク | 投稿記録) 編集の要約なし |
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| ja = 特徴的なヴァル | | ja = 特徴的なヴァル | ||
}} | }} | ||
ある[[オクターブ平均律]]における'''パテントヴァル'''(patent val、特徴的なヴァル)または'''最近傍マッピング'''(nearest edomapping)とは、その平均律チューニング(純正律との対応を定めていないただの等間隔ピッチ集合。以下''n''-等分律と書く)において各素数音程を[[直接近似|最近接丸め]]して得られる[[ヴァル]] | ある[[オクターブ平均律]]における'''パテントヴァル'''(patent val、特徴的なヴァル)または'''最近傍マッピング'''(nearest edomapping)とは、その平均律チューニング(純正律との対応を定めていないただの等間隔ピッチ集合。以下 ''n''-等分律と書く)において各素数音程を[[直接近似|最近接丸め]]して得られる[[ヴァル]]のことである。この際[[オクターブ]]は純正(誤差なし)とする。これの基本的な使い方は素数音程をステップ数に丸めて、それをもとに任意の純正音程のステップ数を求めることである。 | ||
The '''patent val''' (a.k.a. '''nearest edomapping''') for an [[edo]] is a list of numbers you obtain by finding the closest rounded approximation to each [[prime harmonic]] in the tuning, assuming [[2/1|octaves]] are pure (or in other words, assuming the edo number is an integer). The basic application of a patent val is that you round prime harmonics to edosteps, and then deduce the number of steps of an arbitrary just interval based on its [[prime factorization]]. | The '''patent val''' (a.k.a. '''nearest edomapping''') for an [[edo]] is a list of numbers you obtain by finding the closest rounded approximation to each [[prime harmonic]] in the tuning, assuming [[2/1|octaves]] are pure (or in other words, assuming the edo number is an integer). The basic application of a patent val is that you round prime harmonics to edosteps, and then deduce the number of steps of an arbitrary just interval based on its [[prime factorization]]. | ||
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There are other vals worth considering besides the patent val. Consider the case of 5-limit 17et. {{val| 17 27 39}} is the patent val, meaning each prime individually is as closely approximated as possible (again, assuming pure octaves). However, if that constraint is lifted, and we're allowed to choose the next-closest approximations for prime 5, the overall damage to the consonances we care about can be reduced; in other words, even though 39 steps can take you just a tiny bit closer to prime 5 than 40 steps can, this is a naïve choice which does not take into account whether the errors tend to cancel or reinforce in simple ratios that combine different primes. Considering the problem more deeply in this manner may lead to choosing {{val|17 27 40}} instead. And there are other harmonic reasons to choose {{val| 17 27 40 }} over {{val| 17 27 39 }} as well; it tempers different commas. | There are other vals worth considering besides the patent val. Consider the case of 5-limit 17et. {{val| 17 27 39}} is the patent val, meaning each prime individually is as closely approximated as possible (again, assuming pure octaves). However, if that constraint is lifted, and we're allowed to choose the next-closest approximations for prime 5, the overall damage to the consonances we care about can be reduced; in other words, even though 39 steps can take you just a tiny bit closer to prime 5 than 40 steps can, this is a naïve choice which does not take into account whether the errors tend to cancel or reinforce in simple ratios that combine different primes. Considering the problem more deeply in this manner may lead to choosing {{val|17 27 40}} instead. And there are other harmonic reasons to choose {{val| 17 27 40 }} over {{val| 17 27 39 }} as well; it tempers different commas. | ||
{{val| 17 27 40 }} は17.1edoのパテントヴァルつまり一般化パテントヴァルであり、17.1 × log2(5) = 39.705 は 40 に切り上げられる。本質的にそこにはあるジェネレーターの存在があり、そのサイズは 2<sup>1/17.1</sup> である。これには 17、27、40 ステップがそれぞれ素数 2、3、5 の最良近似になるという事実が伴う。これはつまり、我々は素数を真実に一番近いものにしないように「強制」しているわけではないということである。そうでない(している)例が {{val| 17 27 41 }} である。2 を 17 ステップに、かつ 5 を 41 ステップにマップするジェネレーターサイズを見つけることはできるが、それは必ず 3 を 28 ステップにマップするものになる。(今のは雑な例だが、ミーントーンであって1/2コンマミーントーンに近い {{val| 59 93 136 163 }} (59bcddddd) | {{val| 17 27 40 }} は17.1edoのパテントヴァルつまり一般化パテントヴァルであり、17.1 × log2(5) = 39.705 は 40 に切り上げられる。本質的にそこにはあるジェネレーターの存在があり、そのサイズは 2<sup>1/17.1</sup> である。これには 17、27、40 ステップがそれぞれ素数 2、3、5 の最良近似になるという事実が伴う。これはつまり、我々は素数を真実に一番近いものにしないように「強制」しているわけではないということである。そうでない(している)例が {{val| 17 27 41 }} である。2 を 17 ステップに、かつ 5 を 41 ステップにマップするジェネレーターサイズを見つけることはできるが、それは必ず 3 を 28 ステップにマップするものになる。(今のは雑な例だが、ミーントーンであって1/2コンマミーントーンに近い {{val| 59 93 136 163 }} (59bcddddd) なども一般化パテントヴァルでは表せない。)(可能な組み合わせは右図から容易に読み取れる。) | ||
We can show that {{val| 17 27 40 }} is a generalized patent val because it would be the patent val for 17.1et: 17.1 × log<sub>2</sub>5 = 39.705, which rounds up to 40. Essentially this is showing that there does exist some generator size, 2<sup>1/17.1</sup>, for which it is truly the case that 17, 27, and 40 are the respective best approximations of primes 2, 3, and 5. That is, we are not "forcing" an interpretation of a prime which is not closest to the truth. A counterexample would be {{val| 17 27 41 }}: it is possible to find a generator that maps 2 to 17 steps and 5 to 41 steps, but it would require 3 to be 28 steps (this type of information can be read easily off the nearby visualization). | We can show that {{val| 17 27 40 }} is a generalized patent val because it would be the patent val for 17.1et: 17.1 × log<sub>2</sub>5 = 39.705, which rounds up to 40. Essentially this is showing that there does exist some generator size, 2<sup>1/17.1</sup>, for which it is truly the case that 17, 27, and 40 are the respective best approximations of primes 2, 3, and 5. That is, we are not "forcing" an interpretation of a prime which is not closest to the truth. A counterexample would be {{val| 17 27 41 }}: it is possible to find a generator that maps 2 to 17 steps and 5 to 41 steps, but it would require 3 to be 28 steps (this type of information can be read easily off the nearby visualization). | ||
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Another name for generalized patent val is [[uniform map]] (and an [[integer uniform map]], or [[simple map]], is another name for patent val). | Another name for generalized patent val is [[uniform map]] (and an [[integer uniform map]], or [[simple map]], is another name for patent val). | ||
== | == 詳細な説明 == | ||
[[リミット|''p''-リミット]]の[[ヴァル]]は ''p'' までの素数それぞれを何ステップで表すかを示す数値を並べたものである。 | |||
A [[harmonic limit|''p''-limit]] [[val]] contains the number of steps it takes to get to each prime number up to ''p'', in prime number order: | A [[harmonic limit|''p''-limit]] [[val]] contains the number of steps it takes to get to each prime number up to ''p'', in prime number order: | ||
{{val| [2/1] [3/1] [5/1] [7/1] … [''p''/1] }} | {{val| [2/1] [3/1] [5/1] [7/1] … [''p''/1] }} | ||
与えられた ''N''-edo、つまりオクターブを ''N'' 等分する等分律について、特定のステップ数と素数との間をマップするヴァルを定義することができる。 | |||
Given ''N''-edo, the equal division of the octave into ''N'' parts, we may define vals that map a specific number of N-edo steps to these primes. | Given ''N''-edo, the equal division of the octave into ''N'' parts, we may define vals that map a specific number of N-edo steps to these primes. | ||
任意の素数 ''p'' について対応する ''p''-リミットのヴァルを次の規範的な方法で見つけることができる: {{val| 1 log<sub>2</sub>3 log<sub>2</sub>5 … log<sub>2</sub>''p'' }} を ''N'' 倍({{w|スカラー倍}})してから各要素を整数に丸め(四捨五入す)る。一般的にはこれは可能な中で最も正確なヴァルであることを保証されないが、''N''-edo が ''p''-リミットに応じて十分正確であるならば、そうなるであろう。''patent''という名前はその意味の一つが "obvious" と同義語であることからくる。パテントヴァルはベストチョイスだったりそうでなかったりするが、簡明で明白な選択肢である。 | |||
For any prime ''p'' we can find a corresponding ''p''-limit val in a canonical manner by [[Wikipedia: Scalar multiplication|scalar multiplying]] {{val| 1 log<sub>2</sub>3 log<sub>2</sub>5 … log<sub>2</sub>''p'' }} by ''N'' and rounding to the nearest integer. In general this is not guaranteed to be the most accurate available val, but if ''N''-edo has enough relative accuracy in the ''p''-limit, it will be. The name ''patent'' comes from the fact that "patent" in one sense of the word is a synonym for "obvious"; the patent val may or may not be the best choice but it's the obvious choice. | For any prime ''p'' we can find a corresponding ''p''-limit val in a canonical manner by [[Wikipedia: Scalar multiplication|scalar multiplying]] {{val| 1 log<sub>2</sub>3 log<sub>2</sub>5 … log<sub>2</sub>''p'' }} by ''N'' and rounding to the nearest integer. In general this is not guaranteed to be the most accurate available val, but if ''N''-edo has enough relative accuracy in the ''p''-limit, it will be. The name ''patent'' comes from the fact that "patent" in one sense of the word is a synonym for "obvious"; the patent val may or may not be the best choice but it's the obvious choice. | ||
この工程の考え方の一つが次の問いを立てることである、「各素数を得るのにいくつの 1200 セントなステップ(つまりオクターブ)が必要だろうか?」 2/1 を得るのに 1 個の完全なオクターブが必要で、3/1 を得るのに log<sub>2</sub>3 個分が必要で、5/1 を得るのに log<sub>2</sub>5 個分が必要で、以下同様。これにより {{val| 1 1.585 2.322 2.807 3.459 … log<sub>2</sub>''p'' }} を得る。 | |||
One way to think of this process is to first ask, "How many 1200-cent steps (octaves) does it take to get to each prime?" It takes one full-octave step to get to 2/1, log<sub>2</sub>3 steps to get to 3/1, log<sub>2</sub>5 to get to 5/1, and so on. This gives us {{val| 1 1.585 2.322 2.807 3.459 … log<sub>2</sub>''p'' }}. | One way to think of this process is to first ask, "How many 1200-cent steps (octaves) does it take to get to each prime?" It takes one full-octave step to get to 2/1, log<sub>2</sub>3 steps to get to 3/1, log<sub>2</sub>5 to get to 5/1, and so on. This gives us {{val| 1 1.585 2.322 2.807 3.459 … log<sub>2</sub>''p'' }}. | ||
次の問いは、「それらの同じ場所にいくつの ''N''-edoのステップで到達できるだろうか?」 例えば12edoだったらオクターブを12等分するので先ほどの「オクターブ何個分」を 12 倍すればよい。31edoだったら 31 倍すればよい。 | |||
Then ask, "How many more ''N''-edo steps does it take to get to the same places?" One 12edo step is 1/12th of an octave, by definition; therefore, you need 12 times as many steps to reach 2/1, 3/1, 5/1, … Similarly, one 31edo step is 1/31 of an octave, so you need 31 times as many steps to reach 2/1, 3/1, 5/1, … | Then ask, "How many more ''N''-edo steps does it take to get to the same places?" One 12edo step is 1/12th of an octave, by definition; therefore, you need 12 times as many steps to reach 2/1, 3/1, 5/1, … Similarly, one 31edo step is 1/31 of an octave, so you need 31 times as many steps to reach 2/1, 3/1, 5/1, … | ||
なので、''N''-edoのための ''p''-リミットのパテントヴァルは {{val| 1 1.585 2.322 2.807 … log<sub>2</sub>''p'' }} を ''N'' 倍し、そういえば等分律のステップをさらに細かくするようなことはできないので、結果を一番近い整数に丸める。 | |||
Thus, the way to get the ''p''-limit patent val for ''N''-edo is to multiply {{val| 1 1.585 2.322 2.807 … log<sub>2</sub>''p'' }} by ''N''. Then, since you can't take fractional steps in an edo, you round the results to the nearest integers. | Thus, the way to get the ''p''-limit patent val for ''N''-edo is to multiply {{val| 1 1.585 2.322 2.807 … log<sub>2</sub>''p'' }} by ''N''. Then, since you can't take fractional steps in an edo, you round the results to the nearest integers. | ||