Matrix dimensions

The dimensions of a matrix are the number of rows and columns it has.

Dimensions of a matrix

We write the dimensions of a matrix as , where is the number of rows and is the number of columns.

For example, this matrix has 2 rows and 3 columns, so its dimensions are :

Dimensions of a row vector

A row vector only has one, well, row. So a row vector with 4 columns has dimensions .

A row vector might look something like this:

Dimensions of a column vector

A column vector only has one column. So that means that a column vector with 3 rows has dimensions .

Column vectors look like this, for example:

Dimensions of a square matrix

If we have a square matrix, it has the same number of rows and columns. So a square matrix with 4 rows and 4 columns has dimensions .

A square matrix might look like this, a matrix:

Or, like this, a matrix: