(astronomy) A relative measure of the relationship between stellar magnitude and the distribution of stars between magnitudes

(mathematics) An ordinary trigonometric function

(mathematical analysis) Any smooth (infinitely differentiable) function f, defined on an open set D⊆ℂ( textit or⊆ℝ), whose value in some neighbourhood of any given point x_0∈D is given by the Taylor series ∑ₙ₌₀ ᪲(f⁽ⁿ⁾(x_0))/(n!)(x-x_0)ⁿ.

(mathematics) Any function that is a solution of the hypergeometric equation; usually an expansion of an hypergeometric series

(mathematics) A function whose value is always the same as its independent variable, and for which the codomain equals the domain.

(mathematics) A printed tabulation of selected values of a function corresponding to selected independent variables; e.g. a table of logarithms.

(mathematics) For a given function f, another function, denoted f⁻¹, that reverses the mapping action of f; (formally) given a function f:X→Y, a function g:Y→X such that, ∀x∈X,f(x)=y⟹g(y)=x.

(mathematics) Any function, in the calculus of variations, that satisfies the Euler equations

(mathematics) A function of two, three or n variables which is a solution to any of Laplace's equations

(mathematics) Any function whose values are points