Note on subdirect sums of SDD(p) matrices
Qilong Liu, Jianfeng He, Lei Gao, Chaoqian Li · Linear and Multilinear Algebra · 2020
Some sufficient conditions ensuring that the subdirect sum of p-norm strictly diagonally dominant [or, for short, SDD(p)] matrices is in the class of SDD(p) matrices, are given. In particular, it is shown that the subdirect sum of overlapping principal submatrices of an SDD(p) matrix is also an SDD(p) matrix. Some examples are also given that illustrate the conditions presented.