(computing) Any character used to specify a function of a piece of software or hardware (such as carriage return of a printer)

(mathematics) Any function of a complex variable that is holomorphic throughout the complex plane

(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.

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

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

(mathematics) Any function in which an independent variable is in the form of an exponent; they are the inverse functions of logarithms