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

(mathematics) An orthogonal function whose inner product with itself is unity

(mathematics) Any function whose value changes sign if the independent variable changes sign i.e. f(-x) = -f(x)

(mathematics) Either of a pair of functions whose inner product is zero

(mathematics) An ordinary trigonometric function

(mathematics) Any function whose value is the solution of a polynomial; an element of a subring of the ring of all functions over an integral domain, which subring is the smallest to contain all the constant functions and also the identity function. (If the polynomial is multivariate then there is a different identity function corresponding to each variable.)

(mathematics) A function where the independent variable is raised to a particular real number power.

(mathematics) Any function that applies constraints to a maximum or minimum problem

(computing) Any of a set of subroutines that perform standard mathematical functions included in a programming language; either included in a program at compilation time, or called when a program is executed

(mathematics) Any function whose values are points