Fast QR iterations for unitary plus low rank matrices

Roberto Bevilacqua, Gianna M. Del Corso, Luca Gemignani

Some fast algorithms for computing the eigenvalues of a block companion matrix $A=U+X{Y}^H$, where $U\in {\mathbb{C}}^{n\times n}$ is unitary block circulant and $X, Y \in\mathbb{C}…