Octatonic scale scale" . The twelve tones of the chromatic scale are covered by three disjoint diminished seventh chords. The notes from two such seventh-chords combination form an octatonic collection. Because there are three ways to select two from three, there are three octatonic scales in the twelve-tone system. Each octatonic scale has exactly two modes: the first begins its ascent with a whole step, while the second begins its ascent with a half step (semitone). These modes are sometimes referred to as the "whole step/half-step diminished scale" and the "half-step/whole step diminished scale", respectively. Each of the three distinct scales can
Diatonic scale Pythagorean tuning: Six of the "fifth" intervals (C–G, D–A, E–B, F–C', G–D', A–E') are all = 1.5, but B–F' is the discordant tritone, here ≈ 1.423828125. Extending the series of fifths to eleven fifths would result into the Pythagorean Chromatic scale. It would add pitches for the five "piano black key" notes, for instance A–E–B–F–C–G–D–A–E–B–F–C–G. A and G are commonly thought of as being the same note, but as worked out in this way, G is higher pitch than A by about 1.01364 (, the Pythagorean comma, about 24% of a semitone, = ). Depending on whether one chooses A