The Pythagorean comma can be also defined as the difference between a Pythagorean apotome and a Pythagorean limma ( i . e ., between a chromatic and a diatonic semitone, as determined in Pythagorean tuning ), or the difference between twelve just perfect fifths and seven octaves, or the difference between three Pythagorean ditones and one octave ( this is the reason why the Pythagorean comma is also called a " ditonic comma " ).
