Definitions and Notation

A matrix is an array of numbers or symbols. We usually designate a matrix with an uppercase letter:

The size of a matrix is indicated by specifying the number of rows and columns.

For example, matrix A has 3 rows and 1 column, so we say it is a 3 X 1 matrix (pronounced "3 by 1").

Matrix B is a 2 X 3 and matrix C above is a 2 X 2, or a square matrix.

The numbers in the matrix are called elements. Their position is indicated by specifying the row and column they are in using subscripts.

For example, in matrix B: