Computing matrix–vector products with centrosymmetric and centrohermitian matrices

AbstractAn algorithm proposed recently by Melman reduces the costs of computing the product Ax with a symmetric centrosymmetric matrix A as compared to the case of an arbitrary A. We show that the same result can be achieved by a simpler algorithm, which requires only that A be centrosymmetric. However, if A is hermitian or symmetric, this can be exploited to some extent. Also, we show that similar gains are possible when A is a skew-centrosymmetric or a centrohermitian matrix