Modified gravity for surveys
  We present a new parameterization for the equation of state (EoS)
$\omega_X=P_X/\rho_X$, which can reproduce a $f(R)$-like evolution with a
precision between $[0.5\%-0.8\%]$ over the numerical solutions. Also, our
proposal can render a variety of popular $f(R)$ models that are considered as
viable candidates for the cosmic late time acceleration. By using observational
data from baryonic acoustic oscillations, supernovae and cosmic chronometers we
investigate the constraints on the new EoS parameters. This proposal set a EoS
formulation which can be used in an efficient way and makes a good candidate to
be implemented in a variety of surveys in order to test the $f(R)$ generic
behaviour.
