Function
In Mathematics, a means of associating two (or more) quantities (or variables). Each variable has a disinctive role.
The independent variable is a value selected from a set called the domain of the function.
The dependent variable is a value (in a set called the range of the function) which is determined by the value of the independent variable.
A function may be specified by giving an algorithm (or rule) which yields the value of the dependent variable when the value of the independent variable is provided as input.
A function may be specified by a of ordered pairs of values.
A function may be described by a graph of points in two dimensions presenting (conventionally) the independent variable as the horizontal component and the dependent variable as the vertical component.
The concept of a function has been generalized to include arbitrary domains and ranges, the most common on which is the vector valued function in which the range is a set, not of numbers, but of n-tuples or vectors.
Dick Beldin
