There are a number of functions in mathematics commonly denoted with a Greek letter lambda. Examples of one-variable functions denoted 
with a lower case lambda include the Carmichael functions, Dirichlet lambda function, elliptic lambda function, and Liouville function. Examples of one-variable functions denoted 
with an upper case lambda 
include the Mangoldt function and the lambda function defined by Jahnke and Emden (1945).
The triangle function, illustrated above, is commonly denoted 
.
The lambda function defined by Jahnke and Emden (1945) is
 | (1) |
where 
is a Bessel function of the first kind and 
is the gamma function. 
, and taking 
gives the special case
 | (2) |
where 
is the jinc function.
A two-variable lambda function is defined as
 | (3) |
where 
is the gamma function (McLachlan et al. 1950, p. 9; Prudnikov et al. 1990, p. 798; Gradshteyn and Ryzhik 2000, p. 1109).
, 
, 
, 
, 
." §9.64 in