When differentiating a matrix by a matrix it is true that dA(X)/dX is the same thing as dvec(A(X))/dvec(X) acorrording to this paper.

So, I compared kronecker product representation with vec operator representation following case.

$\mathbf{Y}=(2,3)$, $\mathbf{X}=(4,2)$

$$ \begin{aligned} \frac{\partial \mathbf{Y}}{\partial \mathbf{X}} &= \frac{\partial }{\partial \mathbf{X}} \otimes \mathbf{Y} \\[10pt] &=\left[\begin{array}{cc} \dfrac{\partial }{\partial X_{11}} & \dfrac{\partial }{\partial X_{12}} \\ \dfrac{\partial }{\partial X_{21}} & \dfrac{\partial }{\partial X_{22}} \\ \dfrac{\partial }{\partial X_{31}} & \dfrac{\partial }{\partial X_{32}} \\ \dfrac{\partial }{\partial X_{41}} & \dfrac{\partial }{\partial X_{42}} \end{array}\right] \otimes \mathbf{Y} \\[10pt] &= \left[\begin{array}{ccc|ccc} \dfrac{\partial Y_{11}}{\partial X_{11}} & \dfrac{\partial Y_{12}}{\partial X_{11}} & \dfrac{\partial Y_{13}}{\partial X_{11}} & \dfrac{\partial Y_{11}}{\partial X_{12}} & \dfrac{\partial Y_{12}}{\partial X_{12}} & \dfrac{\partial Y_{13}}{\partial X_{12}} \\ \dfrac{\partial Y_{21}}{\partial X_{11}} & \dfrac{\partial Y_{22}}{\partial X_{11}} & \dfrac{\partial Y_{23}}{\partial X_{11}} & \dfrac{\partial Y_{21}}{\partial X_{12}} & \dfrac{\partial Y_{22}}{\partial X_{12}} & \dfrac{\partial Y_{23}}{\partial X_{12}} \\[10pt] \hline \dfrac{\partial Y_{11}}{\partial X_{21}} & \dfrac{\partial Y_{12}}{\partial X_{21}} & \dfrac{\partial Y_{13}}{\partial X_{21}} & \dfrac{\partial Y_{11}}{\partial X_{22}} & \dfrac{\partial Y_{12}}{\partial X_{22}} & \dfrac{\partial Y_{13}}{\partial X_{22}} \\ \dfrac{\partial Y_{21}}{\partial X_{21}} & \dfrac{\partial Y_{22}}{\partial X_{21}} & \dfrac{\partial Y_{23}}{\partial X_{21}} & \dfrac{\partial Y_{21}}{\partial X_{22}} & \dfrac{\partial Y_{22}}{\partial X_{22}} & \dfrac{\partial Y_{23}}{\partial X_{22}} \\[10pt] \hline \dfrac{\partial Y_{11}}{\partial X_{31}} & \dfrac{\partial Y_{12}}{\partial X_{31}} & \dfrac{\partial Y_{13}}{\partial X_{31}} & \dfrac{\partial Y_{11}}{\partial X_{32}} & \dfrac{\partial Y_{12}}{\partial X_{32}} & \dfrac{\partial Y_{13}}{\partial X_{32}} \\ \dfrac{\partial Y_{21}}{\partial X_{31}} & \dfrac{\partial Y_{22}}{\partial X_{31}} & \dfrac{\partial Y_{23}}{\partial X_{31}} & \dfrac{\partial Y_{21}}{\partial X_{32}} & \dfrac{\partial Y_{22}}{\partial X_{32}} & \dfrac{\partial Y_{23}}{\partial X_{32}} \\[10pt] \hline \dfrac{\partial Y_{11}}{\partial X_{41}} & \dfrac{\partial Y_{12}}{\partial X_{41}} & \dfrac{\partial Y_{13}}{\partial X_{41}} & \dfrac{\partial Y_{11}}{\partial X_{42}} & \dfrac{\partial Y_{12}}{\partial X_{42}} & \dfrac{\partial Y_{13}}{\partial X_{42}} \\ \dfrac{\partial Y_{21}}{\partial X_{41}} & \dfrac{\partial Y_{22}}{\partial X_{41}} & \dfrac{\partial Y_{23}}{\partial X_{41}} & \dfrac{\partial Y_{21}}{\partial X_{42}} & \dfrac{\partial Y_{22}}{\partial X_{42}} & \dfrac{\partial Y_{23}}{\partial X_{42}} \end{array} \right] \end{aligned} $$


$ \text{vec}(\mathbf{Y})= \mathbf{y}= \begin{bmatrix} y_{11} & y_{21} & y_{12} & y_{22} & y_{13} & y_{23} \end{bmatrix}^T$

$ \text{vec}(\mathbf{X})= \mathbf{x}= \begin{bmatrix} x_{11} & x_{21} & x_{31} & x_{41} & x_{12} & x_{22} & x_{32} & x_{42} \end{bmatrix}^T$

$$ \begin{aligned} \frac{\partial \text{vec}(\mathbf{Y})}{\partial \text{vec}(\mathbf{X})} &= \frac{\partial \mathbf{y}}{\partial \mathbf{x}} \\ &= \left[\begin{array}{cccccc} \dfrac{\partial Y_{11}}{\partial X_{11}} & \dfrac{\partial Y_{21}}{\partial X_{11}} & \dfrac{\partial Y_{12}}{\partial X_{11}} & \dfrac{\partial Y_{22}}{\partial X_{11}} & \dfrac{\partial Y_{13}}{\partial X_{11}} & \dfrac{\partial Y_{23}}{\partial X_{11}} \\[5pt] \dfrac{\partial Y_{11}}{\partial X_{21}} & \dfrac{\partial Y_{21}}{\partial X_{21}} & \dfrac{\partial Y_{12}}{\partial X_{21}} & \dfrac{\partial Y_{22}}{\partial X_{21}} & \dfrac{\partial Y_{13}}{\partial X_{21}} & \dfrac{\partial Y_{23}}{\partial X_{21}} \\[5pt] \dfrac{\partial Y_{11}}{\partial X_{31}} & \dfrac{\partial Y_{21}}{\partial X_{31}} & \dfrac{\partial Y_{12}}{\partial X_{31}} & \dfrac{\partial Y_{22}}{\partial X_{31}} & \dfrac{\partial Y_{13}}{\partial X_{31}} & \dfrac{\partial Y_{23}}{\partial X_{31}} \\[5pt] \dfrac{\partial Y_{11}}{\partial X_{41}} & \dfrac{\partial Y_{21}}{\partial X_{41}} & \dfrac{\partial Y_{12}}{\partial X_{41}} & \dfrac{\partial Y_{22}}{\partial X_{41}} & \dfrac{\partial Y_{13}}{\partial X_{41}} & \dfrac{\partial Y_{23}}{\partial X_{41}} \\[5pt] \dfrac{\partial Y_{11}}{\partial X_{12}} & \dfrac{\partial Y_{21}}{\partial X_{12}} & \dfrac{\partial Y_{12}}{\partial X_{12}} & \dfrac{\partial Y_{22}}{\partial X_{12}} & \dfrac{\partial Y_{13}}{\partial X_{12}} & \dfrac{\partial Y_{23}}{\partial X_{12}} \\[5pt] \dfrac{\partial Y_{11}}{\partial X_{22}} & \dfrac{\partial Y_{21}}{\partial X_{22}} & \dfrac{\partial Y_{12}}{\partial X_{22}} & \dfrac{\partial Y_{22}}{\partial X_{22}} & \dfrac{\partial Y_{13}}{\partial X_{22}} & \dfrac{\partial Y_{23}}{\partial X_{22}} \\[5pt] \dfrac{\partial Y_{11}}{\partial X_{32}} & \dfrac{\partial Y_{21}}{\partial X_{32}} & \dfrac{\partial Y_{12}}{\partial X_{32}} & \dfrac{\partial Y_{22}}{\partial X_{32}} & \dfrac{\partial Y_{13}}{\partial X_{32}} & \dfrac{\partial Y_{23}}{\partial X_{32}} \\[5pt] \dfrac{\partial Y_{11}}{\partial X_{42}} & \dfrac{\partial Y_{21}}{\partial X_{42}} & \dfrac{\partial Y_{12}}{\partial X_{42}} & \dfrac{\partial Y_{22}}{\partial X_{42}} & \dfrac{\partial Y_{13}}{\partial X_{42}} & \dfrac{\partial Y_{23}}{\partial X_{42}} \end{array} \right] \end{aligned} $$

If these results are the same, how do I transpose $\frac{\partial }{\partial \mathbf{X}} \otimes \mathbf{Y}$ to make it equal to $\frac{\partial \text{vec}(\mathbf{Y})}{\partial \text{vec}(\mathbf{X})}$?


The derivative operation is a distraction, so let's omit it.

Given the matrices $$\eqalign{ X &\in {\mathbb R}^{m\times n} \cr Y &\in {\mathbb R}^{p\times q} \cr }$$ and their Kronecker products $$\eqalign{ A &= X\otimes Y &\in {\mathbb R}^{mp\times nq} \cr B &= {\rm vec}(X)\otimes {\rm vec}(Y)^T &\in {\mathbb R}^{mn\times pq}\cr }$$ you want to know how to transform $A \implies B$

The elements in these matrices are identical. The only difference is in the matrix dimensions and in the ordering of the elements.

Vectorizing the matrices yields two vectors related by a permutation. $$\eqalign{ P\,{\rm vec}(A) &= {\rm vec}(B) \cr Pa &= b \cr P_{ij}\,a_j &= b_i \cr }$$ The elements of the permuation are easy to find:
   $P_{ij}$ equals one if the $j^{th}$ element of $a$ maps to the $i^{th}$ element of $b$.

The single-entry matrix $E_{mn}$ has all elements equal to zero, except for the $(m,n)$ element which is equal to one. Replacing $(X,Y)$ by single-entry matrices leads to $(A,B)$ becoming single-entry matrices and $(a,b)$ becoming single-entry vectors.

The non-zero elements of $P$ can be found by iterating through every possible single-entry matrix for the input matrices $X \,{\rm and}\, Y$. Then setting $\,P_{ij}=1$, where the non-zero elements of the output vectors $(b,a)$ are observed at $(b_i,a_j)$.

The permutation depends only on the dimensions of the starting matrices. For your derivative expressions the dimensions are $(m,n,p,q)=(4,2,2,3)$ and the transformation is
$${\rm vec}\Bigg(\frac{\partial{\rm vec}(Y)}{\partial{\rm vec}(X)}\Bigg) = P\,\,{\rm vec}\Bigg(\frac{\partial}{\partial X}\otimes Y\Bigg) $$


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