English
BlockDiag is submatrix-compatible: (blockDiagonal' M).submatrix equals blockDiagonal M.
Русский
BlockDiagonal' сохраняет подматрицу: (blockDiagonal' M).submatrix = blockDiagonal M.
LaTeX
$$$ (blockDiagonal' M).submatrix (Prod.toSigma \circ Prod.swap) (Prod.toSigma \circ Prod.swap) = blockDiagonal M $$$
Lean4
@[simp]
theorem blockDiag_sub [AddGroup α] (M N : Matrix (m × o) (n × o) α) : blockDiag (M - N) = blockDiag M - blockDiag N :=
map_sub (blockDiagAddMonoidHom m n o α) M N