Rotation number for almost periodic Dirac operators (Q1103766)

The system of the Dirac equations \((Bd/dx+\Omega (x))\vec y=\lambda \vec y\) on \({\mathbb{R}}\) with \[ B=\left[\begin{matrix} 0&1\\ -1&0\end{matrix} \right],\quad \Omega (x)=\left[ \begin{matrix} p(x)^r(x)\\ r(x)&-p(x)\end{matrix} \right] \] is considered. It is assumed that p, r are real almost periodic functions. The author presents some properties of the rotation number for this system.