# What is a unit matrix?

Dec 17, 2014

The unit matrix is every $n$x $n$ square matrix made up of all zeros except for the elements of the main diagonal that are all ones.
For example:

It is indicated as ${I}_{n}$ where $n$ representes the size of the unit matrix.

The unity matrix in linear algebra works a little bit like the number 1 in normal algebra so that if you multiply a matrix by the unit matrix you get the same initial matrix!