Sankhya: The Indian Journal of Statistics

1994, Volume 56, Series A, Pt. 2 , pp. 347--357

EP PERTURBATIONS

By

ROBERT E. HARTWIG, *University of Bradford*

SUMMARY. Necessary and sufficient conditions are given for the block matrix perturbation $M=\left[\begin{array}{cc} A & C \\B & D \end{array} \right]$ and the rank-one perturbation **x =A-cb***, of a square matrix **A**, to be EP.

*AMS subject classification.* 15A57,15A09.

*Key words and phrases.* EP matrices.