Subdirect sums of nonsingular M-matrices and of their inverses
Rafael Bru, Francisco Pedroche, Daniel B. Szyld · Electronic Journal of Linear Algebra · 2005
The question of when the subdirect sum of two nonsingular M -matrices is a nonsingular M -matrix is studied. Sufficient conditions are given. The case of inverses of M -matrices isalso studied. In particular, it is shown that the subdirect sum of overlapping principal submatricesof a nonsingular M -matrix is a nonsingular M -matrix. Some examples illustrating the conditionspresented are also given.