There are two functions commonly denoted , each of which is defined in terms of integrals. Another
unrelated mathematical function represented using the Greek letter is the Möbius function.
where is the gamma
function (Erdélyi et al. 1981a, p. 388; Prudnikov et al.
1990, p. 798; Gradshteyn and Ryzhik 2000, p. 1109), while the three-argument
-function is defined by
(Prudnikov et al. 1990, p. 798; Gradshteyn and Ryzhik 2000, p. 1109).