Heptatonic scale are considered subsets of a twelve-pitch scale roughly analogous to the Western chromatic scale. The first and fifth melakarta tones, corresponding to the first and eighth chromatic tones, are invariable in inflection, and the fourth melakarta tone, corresponding to the sixth or seventh chromatic tone, is allowed one of two inflections only, a natural ("shuddah") position and a raised ("tivra") position. The second and third melakarta tones can be picked from the 4 chromatic tones (second through fifth), and similarly for the sixth and seventh. Thus the number of possible forms is equal to twice the square of the number
Diatonic scale the ancient Greeks. In musical set theory, Allen Forte classifies diatonic scales as set form 7–35. This article does not concern alternative seven-note diatonic scales such as the harmonic minor or the melodic minor. Western music from the Middle Ages until the late 19th century (see common practice period) is based on the diatonic scale and the unique hierarchical relationships created by this system of organizing seven notes. There is one claim that the 45,000-year-old Divje Babe Flute uses a diatonic scale, but there is no proof or consensus it is even a musical instrument. There is evidence that the