Real Functions: Identity Function
An identity function is a function that always returns the same value as its argument. In other words, the identity function is the function f(x) = x.
A sampling of data for the identity function is presented in tabular form below:
| x | −999 | −10 | 0 | π | 5 | 100 | 9999 |
| f (x) | −999 | −10 | 0 | π | 5 | 100 | 9999 |
Additionally, graphical representation of the identity function is depicted below:
As visible above, the graph of the identity function consists of a 45o line through the origin. Any point of the identity function may be written as (x, x) since f(x) = x.