Octave is FOSS matlab. It can read .m files and .mat variables.

Open a text file octaveplot and type an m file octaveplot.m

x=0:10;y=exp(x); [x' y']
plot(x,y,'-ok')
pause

pipe it to octave with the quiet option -q

cat octaveplot.m | octave -q

That will print a table of the values of the exponential function and plots it. The beauty of this is that you can draw plots in a text environment (such as Termux), too. That used to work on my phone but now is giving me a “bus error”. Octave uses gnuplot for its plotting under the hood.