Subdirect sums of doubly diagonally dominant matrices
Subdirect sums of doubly diagonally dominant matrices
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 …