ABSTRACT: Given a symmetric matrix X, we consider the problem of finding a low-rank positive approximant of X. That is, a symmetric positive semidefinite matrix, S, whose rank is smaller than a given ...

College of Mathematics and Information Science, Shangqiu Normal University, Shangqiu, China. In the last decades considerable attention has been paid to upper triangular operator matrices, ...

In this work, the notion of extended eigenvalues of a 2 × 2 lower triangular operator matrix has been researched. More precisely, the relations between the extended spectrum of a 2 × 2 lower ...

The matrix multiplication infix operator (*) produces a new matrix by performing matrix multiplication. The first matrix must have the same number of columns as the second matrix has rows. The new ...