The perturbation of the Drazin inverse and oblique projection Original Research Article

Let A and E be n × n matrices and B = A+E. Denote the Drazin inverse of A by View the MathML source. We present bounds for View the MathML source, View the MathML source, View the MathML source, and View the MathML source under the weakest condition core rank B = core rankA. The hard problem due to Campbell and Meyer in [1] is completely solved.