# Function - Invariant

> Code - (Programming|Computer) Language > (Function | Operator | Map | Mapping | Transformation | Method | Rule | Task | Subroutine)

### Table of Contents

## 1 - About

A function (or property) is invariant under a certain family of transformations if its value does not change when a transformation from this family is applied to its argument.

See also: Function - Covariant

## 2 - Articles Related

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## 3 - Example

The area of a 2D surface is invariant under 2D rotations, since rotating a 2D surface does not make it any smaller or bigger.