1. Faculty of Mathematics and Sciences , University of Ni? , Vi?egradska 33, 18000 Ni?, Serbia;2. Department of Mathematics and Statistics , University of Melbourne , Melbourne, VIC 3010, Australia
Abstract:
We obtain new representations for the general positive and real-positive solutions of the equation axa*=c in a C*-algebra using the characterization of positivity based on a matrix representation of an element and the generalized Schur complement. Applications to the equation AXA*=C for operators between Hilbert spaces and for finite matrices are given.