Direct approximation: Difference between revisions

Line 27:

== Problems ==

~~Although~~ direct approximation ~~is perhaps easier to understand than mapping through [[val]]s, it~~ is not always practical in harmony. For example, it is impossible to construct a major triad using the direct approximations of 3/2, 5/4, and 6/5 in [[17edo]] since the step numbers do not add up (5 steps + 4 steps ≠ 10 steps).

Unless one sticks to one or two notes at a time, direct approximation is not always practical in harmony. For example, it is impossible to construct a [[4:5:6|just major triad]] using the direct approximations of 3/2, 5/4, and 6/5 in 17edo since the step numbers do not add up (5 steps + 4 steps ≠ 10 steps). The closest 3/2 and 5/4 imply the second closest 6/5; the closest 3/2 and 6/5 imply the second closest 5/4; and the closest 5/4 and 6/5 imply the second closest 3/2. We see one of the direct approximations must be given up. This is called [[consistency|inconsistency]], and chords like this exists in every edo.

In [[regular temperament theory]], intervals are mapped through [[val]]s. Although more complex, it recognizes the fact that intervals like 3/2, 5/4, and 6/5 are related, as the number of steps of one interval is determined once the other two have been determined. The three situations in the above example correspond to using vals {{val| 17 27 39 }}, {{val| 17 27 40 }}, and {{val| 17 26 39 }}, respectively.

[[Category:Terms]]

[[Category:Method]]

@@ Line 27: / Line 27: @@
 == Problems ==
-Although direct approximation is perhaps easier to understand than mapping through [[val]]s, it is not always practical in harmony. For example, it is impossible to construct a major triad using the direct approximations of 3/2, 5/4, and 6/5 in [[17edo]] since the step numbers do not add up (5 steps + 4 steps ≠ 10 steps).
+Unless one sticks to one or two notes at a time, direct approximation is not always practical in harmony. For example, it is impossible to construct a [[4:5:6|just major triad]] using the direct approximations of 3/2, 5/4, and 6/5 in 17edo since the step numbers do not add up (5 steps + 4 steps ≠ 10 steps). The closest 3/2 and 5/4 imply the second closest 6/5; the closest 3/2 and 6/5 imply the second closest 5/4; and the closest 5/4 and 6/5 imply the second closest 3/2. We see one of the direct approximations must be given up. This is called [[consistency|inconsistency]], and chords like this exists in every edo.
+In [[regular temperament theory]], intervals are mapped through [[val]]s. Although more complex, it recognizes the fact that intervals like 3/2, 5/4, and 6/5 are related, as the number of steps of one interval is determined once the other two have been determined. The three situations in the above example correspond to using vals {{val| 17 27 39 }}, {{val| 17 27 40 }}, and {{val| 17 26 39 }}, respectively.
 [[Category:Terms]]
 [[Category:Method]]