DXD

diagonal matrix X matrix X diagonal matrix

$$\underset{m\times m}{A}\cdot\underset{m\times n}{X}\cdot\underset{n\times n}{C}= \begin{bmatrix} a_{1}X_{11}c_{1} & a_{1}X_{12}c_{2} &\cdots&\cdots \\ a_{2}X_{21}c_{1} & a_{2}X_{22}c_{2} &\cdots &\cdots\\ \cdots & \cdots &\cdots & a_{m}X_{mn}c_{n}\ \end{bmatrix}$$

* $a_k$ , $c_k$ are $k$th diagonal elements of diagonal matrices A and C.