Diagonal Matrix

Definition

Diagonal matrix is a square matrix in which all the entries off the main diagonal are $0$‘s .

Example

$$\left[\begin{array}{cc}2& 0\\ 0& -5\end{array}\right],\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right],\left[\begin{array}{cccc}6& 0& 0& 0\\ 0& -4& 0& 0\\ 0& 0& 0& 0\\ 0& 0& 0& 8\end{array}\right],\left[\begin{array}{cc}0& 0\\ 0& 0\end{array}\right]$$