On eigenvalues of rectangular matrices

Julius Borcea, Boris Shapiro, Michael Shapiro

Given a $(k+1)$-tuple $A,B_1,...,B_k$ of $(m\times n)$-matrices with $m\le n$ we call the set of all $k$-tuples of complex numbers $\{\la_1,...,\la_k\}$ such that the linear combi…