Some invariants of $U(1,1;\mathbb{H})$ and diagonalization

Cailing Yao, Bingzhe Hou, Xiaoqi Feng

Denote by $\mathbb{H}$ the set of all quaternions. We are interested in the group $U(1,1;\mathbb{H})$, which is a subgroup of $2\times 2$ quaternionic matrix group and is sometimes…