A function is a core concept in math and computing. In math, a basic function usually takes a number as input and returns a number as output.

For example, a simple function which takes in a number as input and returns twice the number as output is shown below.

In plain language, this represents the function which has one input variable and returns the value expression . Shown below is a table of input and output of the function.

Input | Output |
---|---|

1 | 2 |

2 | 4 |

3 | 6 |

4 | 8 |

Functions are often visualized in the cartesian coordinate system by plotting their values in 2D space. Shown below is the graph of the example function.

The input of the function is denoted with the variable and the output of the function is denoted with the variable .

Points on the function, like the three labeled on the plot are written using the notation below.

See the function reference for a list of math functions.