Annemarie Luger: Poles and zeros of matrix functions

For matrix valued functions the concept of poles and zeros is a bit more complicated than for scalar valued functions, basically since poles can appear in certain directions only. Moreover, a point can be both pole and zero.

In this talk we review the concept of poles and the — in this context very useful — tool of pole-cancellation functions and, in particular, present recent results on the characterization of multiplicities of (generalized) poles.