Definition:Unit Matrix/Examples/3 x 3

Definition

The $3 \times 3$ unit matrix is as follows:

$\mathbf I_3 = \begin{bmatrix}

1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \\ \end{bmatrix}$

Sources

• 2008: David Joyner: Adventures in Group Theory (2nd ed.) ... (previous) ... (next): Chapter $2$: 'And you do addition?': $\S 2.2$: Functions on vectors: $\S 2.2.2$: $3 \times 3$ matrices: Example $2.2.1$