Matrices: Lecture Notes

A matrix (plural: matrices) is a two-dimensional rectangular data structure. Examples:

1. $\begin{bmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \end{bmatrix}$

2. $\begin{bmatrix} 😀 \\ 😁 \\ 😎 \\ 😜 \end{bmatrix}$

3. $\begin{bmatrix} \text{Bla} \end{bmatrix}$

4. $\begin{bmatrix} a & b \\ c & d \\ e & f \\ g & h \\ i & j \end{bmatrix}$

$\begin{bmatrix} 65.7 & 62.4 & 73.8 & 76.6 & 75.0 \end{bmatrix}$

6. $\begin{bmatrix} 1 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 0 & 0 & 1 \end{bmatrix}$

Notation: Just as for other data container we've seen (sets and sequences,) matrices will be named using capital letters, such as $A$ (

$A$

), $B$, or $M$. Many textbooks also use boldfaced letters, such as $\textbf{A}$ (

$\textbf{A}$

), $\textbf{B}$, or $\textbf{M}$. Example:

7. $A = \begin{bmatrix} \text{Foo} & \text{Bar} & \text{Baz} \end{bmatrix}$ (

$A = \begin{bmatrix} \text{Foo} & \text{Bar} & \text{Baz} \end{bmatrix}$

)