Sturm-Schroedinger equations $H\psi=E W\psi$ with $H\neq H^\dagger$ and $W\neq W^\dagger \neq I$ are considered, with a weak point of the theory lying in the purely numerical matrix-inversion form of the double-series definition of the necessary metric operator $\Theta$ in the physical Hilbert space of states [M. Znojil, J. Phys. A: Math. Theor. 41 (2008) 215304]. This shortcoming is removed here via an amended, single-series definition of $\Theta$.
Categories: quant-ph