  The present paper is focused on the analysis of the one-dimensional
relativistic gas dynamics equations. The studied equations are considered in
Lagrangian description, making it possible to find a Lagrangian such that the
relativistic gas dynamics equations can be rewritten in a variational form.
Complete group analysis of the Euler-Lagrange equation is performed. The
symmetries found are used to derive conservation laws in Lagrangian variables
by means of Noether's theorem. The analogs of the newly found conservation laws
in Eulerian coordinates are presented as well.
