“…Over the years, various generalizations and extensions of (4) and ( 5) have been obtained in the literature. For instance, see [23,24] for the equality cases; see [2,15,22,4,7] for the extensions of M -matrices. It is worth noting that Lin [16] recently gave a remarkable extension (Theorem 1.1) of Chen's result (5) for positive definite block matrices.…”