Function (music)
In music, function (also harmonic function or tonal function) denotes the relationship of a chord or scale degree to a tonal centre. Two main theories of tonal functions exist today: The German theory created by Hugo Riemann in his Vereinfachte Harmonielehre of 1893, which soon became an international success (English and Russian translations in 1896, French translation in 1899), and which is the theory of functions properly speaking.