We obtain a necessary and sufficient condition for a matrix A to be Birkhoff-James orthogonal to any subspace W of Mn(C). Using this we obtain an expression for the distance of A from any unital C*- subalgebra of Mn(C). © 2013 Elsevier Inc. All rights reserved.

Priyanka Grover

Mathematics

(SoNS) School of Natural Sciences

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