21/13: Difference between revisions

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-'''21/13''', the '''tridecimal supraminor sixth''', is ''ca''. 830 [[cent]]s in size. It has a very good approximation in [[13edo]].
+'''21/13''', the '''tridecimal supraminor sixth''', is ''ca''. 830 [[cent]]s in size. It has a very good approximation in [[13edo]] (and in [[5ed11]]).
-This interval is a ratio of two consecutive Fibonacci numbers, therefore it approximates the [[golden ratio]], specifically [[acoustic phi]]. In this case, 21/13 is ~2.8 [[cent|¢]] flat of the golden ratio.
+This interval is a ratio of two consecutive {{w|Fibonacci numbers}} and thus a convergent to [[acoustic phi]] (the interval of a [[golden ratio]]). In this case, 21/13 is ~2.8{{cent}} flat of acoustic phi. It differs from [[13/8]], the previous such convergent, by [[169/168]], and from the following convergent [[34/21]] by [[442/441]].
 == See also ==