Mapped interval: Difference between revisions

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* A 'y' also looks like a 'g', which is fitting because <math>\mathbf{y}</math> is a generator-count vector, associated with the generator tuning map <math>𝒈</math>, in the sense that intervals are associated with (tempered-prime) tuning maps <math>𝒕</math>, or in other words, <math>𝒕\textbf{i} = 𝒈\textbf{y}</math>.

A "mapped interval" could also be called a "tempered interval", however, "tempered interval" is more ambiguous; "tempered interval" could also refer to a [[span|size]] resulting from mapping an interval by a [[tuning map]] for a temperament (in the same sense that "interval" is used to refer to a "(just) interval's (size)", or it could even refer to a [[projected interval]] such as the {{ket|0 0 1/4}} generator of quarter-comma meantone. Only "''mapp''ed interval" unambiguously refers to an interval that has been transformed only by the ''mapp''ing matrix for a temperament.

A mapped interval therefore refers not to any particular JI interval, but to an equivalence class of JI intervals separated by any combination of the [[comma]]s that are [[tempered out]] by a given temperament. Thus, a regular temperament can be seen as a sort of [[monzo|vector]] generalization of the "modulus" in {{w|modular arithmetic}} - that is, 100/81, 5/4, 81/64, 6561/5120, etc., belong to the same equivalence class "modulo" 81/80 (and in fact, due to the [[Prime number|fundamental theorem of arithmetic]], this can be seen as an actual modulus in logarithmic space, though this uses constructions involving real numbers rather than integers).

== Terminology ==

A "mapped interval" could also be called a "tempered interval"; however, "tempered interval" is more ambiguous: "tempered interval" could also refer to a [[span|size]] resulting from mapping an interval by a [[tuning map]] for a temperament (in the same sense that "interval" is used to refer to a "(just) interval's (size)", or it could even refer to a [[projected interval]] such as the {{ket|0 0 1/4}} generator of quarter-comma meantone. Only "''mapp''ed interval" unambiguously refers to an interval that has been transformed only by the ''mapp''ing matrix for a temperament.

== See also ==

@@ Line 11: / Line 11: @@
 * A 'y' also looks like a 'g', which is fitting because <math>\mathbf{y}</math> is a generator-count vector, associated with the generator tuning map <math>𝒈</math>, in the sense that intervals are associated with (tempered-prime) tuning maps <math>𝒕</math>, or in other words, <math>𝒕\textbf{i} = 𝒈\textbf{y}</math>.
-A "mapped interval" could also be called a "tempered interval", however, "tempered interval" is more ambiguous; "tempered interval" could also refer to a [[span|size]] resulting from mapping an interval by a [[tuning map]] for a temperament (in the same sense that "interval" is used to refer to a "(just) interval's (size)", or it could even refer to a [[projected interval]] such as the {{ket|0 0 1/4}} generator of quarter-comma meantone. Only "''mapp''ed interval" unambiguously refers to an interval that has been transformed only by the ''mapp''ing matrix for a temperament.
+A mapped interval therefore refers not to any particular JI interval, but to an equivalence class of JI intervals separated by any combination of the [[comma]]s that are [[tempered out]] by a given temperament. Thus, a regular temperament can be seen as a sort of [[monzo|vector]] generalization of the "modulus" in {{w|modular arithmetic}} - that is, 100/81, 5/4, 81/64, 6561/5120, etc., belong to the same equivalence class "modulo" 81/80 (and in fact, due to the [[Prime number|fundamental theorem of arithmetic]], this can be seen as an actual modulus in logarithmic space, though this uses constructions involving real numbers rather than integers).
+== Terminology ==
+A "mapped interval" could also be called a "tempered interval"; however, "tempered interval" is more ambiguous: "tempered interval" could also refer to a [[span|size]] resulting from mapping an interval by a [[tuning map]] for a temperament (in the same sense that "interval" is used to refer to a "(just) interval's (size)", or it could even refer to a [[projected interval]] such as the {{ket|0 0 1/4}} generator of quarter-comma meantone. Only "''mapp''ed interval" unambiguously refers to an interval that has been transformed only by the ''mapp''ing matrix for a temperament.
 == See also ==