Inequalities Involving Hadamard Products of Positive Semidefinite Matrices

An inequality established by G. P. H. Styan 1973, Linear Algebra Appl., 6, 217]240. is on the Hadamard product and a correlation matrix. An inequality obtained by B.-Y. Wang and F. Zhang 1997, Linear and Multilinear Algebra, 43, 315]326. involves the Hadamard product and Schur complements. These two inequalities hold in the positive definite matrix case. Based on Albert’s theorem, we present their extensions to cover the positive semidefinite matrix case. We also give relevant inequalities.