Is there a more compact notation for representing a block-diagonal matrix than
$\left[\begin{array}{cccc}
\mathbf{W}_1 & 0 & … & 0\\
0 & \mathbf{W}_2 & … & 0\\
0 & 0 & \ddots & 0\\
0 & 0 & … & \mathbf{W}_n
\end{array}\right]
$
Something as simple as replacing
$\left[\begin{array}{c}
\mathbf{m}_1\\
\mathbf{m}_2\\
\vdots\\
\mathbf{m}_n
\end{array}\right]
$
with
$\left[\mathbf{m}_1^T~\mathbf{m}_2^T~…~\mathbf{m}_n^T\right]^T$
for vectors? I'm just trying to reduce the space required for a manuscript. Is
$
diag\left\{\mathbf{W}_1~ \mathbf{W}_2~…~\mathbf{W}_n \right\}
$
acceptable notation?
Best Answer
$ \text{blkdiag} \left( \left\{ \mathbf{W}_i \right\}_{i=1}^n \right) $