X- factor: A modified relaxation factor to accelerate the convergence rate of the radiative transfer equation with high-order resolution schemes using the Normalized Weighting-Factor method. - Jesús Xamán; Irving Hernández-López; Javier Uriarte-Flores; Iván Hernández-Pérez; Ivett Zavala-Guillén; Pedro Moreno-Bernal; Jesús Fernando Hinojosa (Comput. Phys. Commun., 2018)