Averaged intensity variation a) and residuals (relative percentage difference) compared to those calculated by the Feautrier method b) in different layers in the test model atmosphere. Solid and dashed lines in a) correspond to our calculations with the Feautrier and the short characteristics solution of radiative transfer equation. The solid line in b) describes the difference between the Feautrier and short characteristics solutions. Different symbols correspond to values of J(r) obtained by different authors: (crosses) are from Mihalas et al. (1975), (stars) – from Rogers (1982), (squares) – from Avrett & Loeser (1984), (diamonds) – from Gros et al. (1997), (triangles) – from Atanackovic-Vukmanovic (2003).