Delta-rational chord: Difference between revisions

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For example, take 0.0570 (the LSD error of 0-2\11-4\11 as +1+1, approximately equalized 7:8:9) as a somewhat arbitrary but reasonable upper limit of acceptable error. Consider Semaphore temperament (i.e. 2.3.7[14 & 19]). Using a gen of 260.346c, 0-679c-940c is a Semaphore tuning of 4:6:7 that is perfectly +2+1, but inverting the chord yields 0-260c-521c as our 6:7:8, with LSD error 0.0681; the 7:8:12 has an even higher error of 0.123. This is also evident by the fact that we had to use an extreme tuning of Semaphore, which has CWE generator 249.311c and CTE generator 248.126c. If we use the CTE generator, all three inversions are barely acceptable to unacceptable as simple-DR approximations: 4:6:7 has LSD error 0.0574 from +2+1, 6:7:8 has LSD error 0.0652 from +1+1, and 7:8:12 has LSD error 0.0570 from +1+4.
For example, take 0.0570 (the LSD error of 0-2\11-4\11 as +1+1, approximately equalized 7:8:9) as a somewhat arbitrary but reasonable upper limit of acceptable error. Consider Semaphore temperament (i.e. 2.3.7[14 & 19]). Using a gen of 260.346c, 0-679c-940c is a Semaphore tuning of 4:6:7 that is perfectly +2+1, but inverting the chord yields 0-260c-521c as our 6:7:8, with LSD error 0.0681; the 7:8:12 has an even higher error of 0.123. This is also evident by the fact that we had to use an extreme tuning of Semaphore, which has CWE generator 249.311c and CTE generator 248.126c. If we use the CTE generator, all three inversions are barely acceptable to unacceptable as simple-DR approximations: 4:6:7 has LSD error 0.0574 from +2+1, 6:7:8 has LSD error 0.0652 from +1+1, and 7:8:12 has LSD error 0.0570 from +1+4.
== Finding approximate DR chords in edos ==
Todo: add more heuristics
Some heuristics for finding delta-rational chords:
* If a chord with a given step numbers in an edo is delta-rational it or similar numbers will usually also be delta-rational in nearby edos.


== Higher-order differences of frequency ==
== Higher-order differences of frequency ==