  We study the luminosity function of long gamma-ray bursts (LGRBs) using the
peak flux obtained from three LGRB samples with known redshifts: (a) a sample
of 251 LGRBs from the \textit{Swift/BAT} satellite/instrument; (b) a sample of
37 LGRBs from the \textit{Fermi/GBM} telescope; (c) a sample of 152 GRBs from
the \textit{Konus-Wind} instrument. For the \textit{Swift/BAT} and
\textit{Fermi/GBM} samples, we use data available on the Swift Burst Analyser
websites (\url{http://www.swift.ac.uk/burst_analyser}; \citep{Evans:2010}) and
(\url{http://swift.gsfc.nasa.gov/archive/grb/table/}) and on the Fermi website
(\url{https://heasarc.gsfc.nasa.gov/}\url{W3Browse /fermi /fermigbrst.html};
\citep{{Gruber_2014}, {von_Kienlin_2014}, {Bhat_2016}}) to calculate the
luminosity at the peak of the flux by using a cut-off power-law spectrum (CPL).
For the \textit{Konus-Wind} sample, we use the Yonetoku correlation
relationship \citep{Yonetoku:2010} to determine the isotropic luminosity from
the energy at the peak of the flux measured in the source frame
\citep{Minaev:2019}. With these three samples (totalling 439 GRBs), we use the
Monte Carlo method to synthesize 10,000 "artificial" GRBs similar to each real
GRB by considering that each physical quantity observed obeys a normal
distribution, where the tabulated value and uncertainty represent the mean and
the $3\sigma$ error. The results obtained for the luminosity function from our
data samples are consistent with those published in previous works.
