Plot of the Bessel functions of first kind ${\displaystyle J_{0}(x)}$ in red, ${\displaystyle J_{1}(x)}$ in green and ${\displaystyle J_{2}(x)}$ in blue. The plot was produced running Gnuplot

the file "besselJ.dat" contains the values of the Bessel functions and can be produced with the following Octave commands:

t = 0:0.01:20;
J = [ t; besselj(0,t); besselj(1,t); besselj(2,t) ];
J = J';
save -ascii "besselJ.dat" J;