Diagonal matrix/Action/Exercise

Let

${}D={\begin{pmatrix}d_{11}&0&\cdots &\cdots &0\\0&d_{22}&0&\cdots &0\\\vdots &\ddots &\ddots &\ddots &\vdots \\0&\cdots &0&d_{n-1\,n-1}&0\\0&\cdots &\cdots &0&d_{nn}\end{pmatrix}}\,$

be a diagonal matrix, and ${}M$ an ${}n\times n$-matrix. Describe

${}DM$ and ${}MD$.

Create a solution