Author proved that diagonally schur complement of I-block strictly diagonally dominant matrices was still I-block strictly diagonally dominant matrices,and proved that the diagonally schur complements of I-BDD was still I-BDD by a continuity argument.

• 利用矩阵分块的思想,主要证明了I-块严格对角占优阵的对角schur补仍然是I-块严格对角占优阵,同时利用连续性证明了I-BDD的对角schur补还是I-BDD。