(mathematics) Any function in which an independent variable appears in the form of a logarithm; they are the inverse functions of exponential functions

(mathematics) Any function whose value may be directly calculated from the independent variable.

(mathematics) Any function that is composed of algebraic functions, trigonometric functions, exponential functions and/or logarithmic functions, combined using addition, subtraction, multiplication and/or division

An electronic analog computing device that accepts as input two periodic functions and outputs their mathematical product

(computing) Any of a set of keys on a personal computer or terminal keyboard used to activate a predefined or programmable function.

(computing) A program, module or subroutine etc that returns the value of a defined function

(physics) An approximation to a wave function made by taking a linear combination of simpler functions

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

(mathematics) The function whose value is zero if its independent variable is negative, and one otherwise.

(mathematics) Any function of a complex variable which is periodic in two directions.