21/13: Difference between revisions

@@ Line 1: / Line 1: @@
-'''21/13'''
+{{Infobox Interval
-| 0 1 0 1 0 -1&gt;
+| Name = tridecimal supraminor sixth
+| Color name = thuzo 6th, 3uz6
+| Sound = ji-21-13-csound-foscil-220hz.mp3
+}}
-.25325 cents
+'''21/13''', the '''tridecimal supraminor sixth''', is ''ca''. 830 [[cent]]s in size. It has a very good approximation in [[13edo]], and notably, 5 of these intervals differ from [[11/1]] by 4084223/4084101, a comma of a mere 0.052{{cent}}.
-[[File:ji-21-13-csound-foscil-220hz.mp3]] [[:File:ji-21-13-csound-foscil-220hz.mp3|sound sample]]
+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]].
-The '''tredecimal minor sixth'''. Its inverse is the tredecimal major third [[26/21|26/21]].
+== See also ==
+* [[26/21]] – its [[octave complement]]
+* [[Gallery of just intervals]]
-See [[Gallery_of_Just_Intervals|Gallery of Just Intervals]]
+[[Category:Sixth]]
+[[Category:Supraminor sixth]]
+[[Category:Golden ratio approximations]]