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
Blues scale G, B. The latter is the hexatonic scale (top). The heptatonic, or seven-note, conception of the blues scale is as a diatonic scale (a major scale) with lowered third, fifth, and seventh degrees Blues practice is derived from the "conjunction of 'African scales' and the diatonic western scales". \override Score.TimeSignature #'stencil = ##f \relative c' { </score> Steven Smith argues that, "to assign blue notes to a 'blues scale' is a momentous mistake, then, after all, unless we alter the meaning of 'scale'". An essentially nine-note blues scale is defined by Benward and Saker as a chromatic variation of the