Subdirect sums of doubly diagonally dominant matrices
Yan Ping Zhu, Ting‐Zhu Huang · Electronic Journal of Linear Algebra · 2007
The problem of when the k-subdirect sum of a doubly diagonally dominant matrix(DDD matrix) is also a DDD matrix is studied. Some sufficient conditions are given. The samesituation is analyzed for diagonally dominant matrices and strictly diagonally dominant matrices.Additionally, some conditions are also derived when card(S)>card(S1) which was not studied by Bru, Pedroche and Szyld [Electron. J. Linear Algebra, 15:201-209, 2006]. Examples are given to illustrate the conditions presented