  The determination of the luminosity function (LF) in gamma ray bursts (GRBs)
depends on the adopted cosmology, each one characterized by its corresponding
luminosity distance. Here we analyse three cosmologies: the standard cosmology,
the plasma cosmology, and the pseudo-Euclidean universe. The LF of the GRBs is
firstly modeled by the lognormal distribution and the four broken power law,
and secondly by a truncated lognormal distribution. The truncated lognormal
distribution fits acceptably the range in luminosity of GRBs as a function of
the redshift.
