Does a "vector of vectors" exist, and how would one formulate such a thing?
I have a vector $\vec{a} \in \mathbb{R}^N$ that I would like to divide into 4 vectors of equal length to make notation easier lateron. I would like to use those parts in matrix multiplication later on, e.g.
$$ \begin{bmatrix} \vec{b}_0 \mathbf{A} & \vec{b}_1 \mathbf{B} \\ \vec{b}_2 \mathbf{C} & \vec{b}_3 \mathbf{D} \end{bmatrix} $$
where $\vec{b}_n \in \mathbb{R}^{\frac{N}{4}}$ is the $n$-th part of the original vector $\vec{a}$.
In the NumPy world, I would think of $\vec{b}$ as an $\mathbb{R}^{4 \times \frac{N}{4}}$ matrix and would extract the $n$-th row, but I don't think this would be possible or helpful here.