Let $A \in \mathbb{R}^{N \times N}$ be a D6160: Real square matrix such that
(i) | \begin{equation} A = \begin{bmatrix} A_{1, 1} & 0 & \cdots & 0 \\ 0 & A_{2, 2} & \vdots & 0 \\ \vdots & \cdots & \ddots & \vdots \\ 0 & 0 & \cdots & A_{N, N} \end{bmatrix} \end{equation} |
Then
\begin{equation}
\text{Det} A
= \prod_{n = 1}^N A_{n, n}
\end{equation}