  The equation derived by F. Rohrlich (Phys. Rev. E 77, 046609 (2008)) has been
known for 60 years (C. J. Eliezer, Proc. Royal Soc. London. Ser. A 194, 543
(1948)). For a long time this equation has been considered to be incorrect. If
there is any need to revisit this issue, the only relevant consideration is
that the Eliezer equation is very difficult to solve numerically: the
acceleration being expressed in terms of a function that, itself, depends on
the acceleration.
