# Relation and Function

Not all relations are function but all functions are relation. A good example of a relation that is not a function is a point in the Cartesian coordinate system, say (2, 3). Though 2 and 3 in (2, 3) are related to each other, neither is a function of the other.

Function is a relation between two variables that inhibits an apparent connection. If the variables are *x* and *y*, then *y* can be determined for some range of values of *x*. We call this, *y* as a function of *x* denoted by *y* = *f* (*x*). Differential Calculus is limited only to those relations that are functions defined by equations.