  The stability of astrophysical jets in the linear regime is investigated by
presenting the methodology to find the growth rates of the various
instabilities. We perturb a cylindrical axisymmetric steady jet, linearize the
relativistic ideal magnetohydrodynamic (MHD) equations, and analyze the
evolution of the eigenmodes of the perturbation by deriving the differential
equations that need to be integrated subject to the appropriate boundary
conditions, in order to find the dispersion relation. We also apply the WKBJ
approximation and additionally give analytical solutions in some subcases
corresponding to unperturbed jets with constant bulk velocity along the
symmetry axis.
