Solution of the radiative transfer equation in the separable approximation

The radiative transfer equation in plane-parallel media with coherent isotropic scattering and finite optical depth is solved analytically, utilizing the formalism of meromorphic functions. The solution obtained is well suited for applications to accretion disks due to the imposed property of the slab, such as the presence of the plane of symmetry. The practical performance of the method is discussed and its correctness is checked by comparing the results obtained with those of other methods.