Suppose I have a block diagonal matrix that looks like this
$$C = \begin{bmatrix} A & 0\\ 0 & B\end{bmatrix}$$
then I would write $C = \mbox{diag} (A, B)$, however, what if I have a block diagonal matrix that is mirrored, i.e.
$$D = \begin{bmatrix} 0 & A\\ B & 0\end{bmatrix}$$
How can I express $D$ in mathematical notation?
Best Answer
You may write $D=\operatorname{antidiag}(A,B)$ but this is by no means a standard notation.