Definition:Determinant/Matrix/Order 1

Definition
Let $\mathbf A = \sqbrk a_1$ be a square matrix of order $1$.

That is, let:
 * $\mathbf A = \begin {bmatrix} a_{11} \end {bmatrix}$

Then the determinant of $\mathbf A$ is defined as:
 * $\begin {vmatrix} a_{11} \end {vmatrix} = a_{1 1}$

Thus the determinant of an order $1$ matrix is that element itself.