Plot of the Gamma function ${\displaystyle \Gamma (x)}$. The plot was produced running Gnuplot on the following code:

set terminal svg
set output "Gamma_plot.svg"
set title "Gamma function"
set xrange [-10:10]
set yrange [-10:10]
set key off
set xzeroaxis linetype -1 linewidth 0.5
set yzeroaxis linetype -1 linewidth 0.5
set xtics axis
set ytics axis
plot "gamma.dat" using 1:2 with lines linewidth 2

the file "gamma.dat" contains the values of the Gamma function and can be produced with the following Matlab commands (it is meant to work in Octave, too, but it returns an error in version 2.1.64):

t = -5:0.01:5;
G = [ t; gamma(t) ];
G = G';
save -ascii "gamma.dat" G;