# Functions

A function is a well-behaved relation. Just as with members of our own family, with some members the relation is different than others. Remember, all functions are relations, but not all relations are functions. Mathematically,f:A->B is a function if the relation f associates to every member of the set A ,a unique member of the set B. Set A is known as the domain and set B is known as Codomain . The image set {f(a)\a belongs to B} is the range set.

Example: Every person has a unique finger impression.
If we denote the set of persons as the domain set and the finger impressions the other set (codomain), then this relation is a function.

Some functions:
Periodic functions-- Cosine function , sine function;
Exponential functions;
Logrithmic function.