(mathematics) Any function whose domain is a vector space and whose value is its scalar field

(mathematics, logic) A Boolean function whose value is interpreted as truth or falsity

(management) Any secondary business activity that supports the line functions of a business, but does not directly affect customers or profits

(mathematical analysis) Any complex-valued measurable function whose range is finite.

(mathematics) Any function whose value is the solution of a quadratic polynomial

(mathematics) Any function, of multiple variables, whose value is independent of the order of the variables, i.e. f(a,b) = f(b,a).

(mathematics, computing) A function whose value is chosen at random from its domain / (mathematics) A function chosen at random from a set of functions

(physics) The minimum energy needed to remove an electron from the surface of a material

(computing) Any function that uses recursion and can call itself until a certain condition is met

(mathematics, complex analysis, algebraic geometry) Any function expressible as the quotient of two (coprime) polynomials (and which thus has poles at a finite, discrete set of points which are the roots of the denominator).