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.

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

(mathematical analysis, algebraic geometry) A function defined by a (multivariable) implicit equation when one of the variables is regarded as the value of the function, especially where said equation is such that the value is not directly calculable from the other variables.

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