## Differential Equations and Linear Algebra (4th Edition)

One example is $\begin{bmatrix} 1&0&0\\ 0&2&0\\ 0&0&3 \end{bmatrix}$
Diagonal matrix is a square matrix in which all its non diagonal elements are zero. There will be 3 rows and 3 columns in a 3×3 matrix. An example for a 3×3 diagonal matrix is $\begin{bmatrix} 1&0&0\\ 0&2&0\\ 0&0&3 \end{bmatrix}$.