Matrices

3.1 Introduction

A matrix is a rectangular arrangement of numbers (or functions) in rows and columns, enclosed in brackets.

A matrix of order $m \times n$ has $m$ rows and $n$ columns:

$$A = \begin{bmatrix} a_{11} & a_{12} & \cdots & a_{1n} \\ a_{21} & a_{22} & \cdots & a_{2n} \\ \vdots & \vdots & \ddots & \vdots \\ a_{m1} & a_{m2} & \cdots & a_{mn} \end{bmatrix} = [a_{ij}]_{m \times n}$$