gnuplot at the command prompt.
plot and the syntax is this:
plot [var=a:b] f1(var), f2(var), ...Some examples probably will clarify things:
plot [n=1:100] n*n, 0.5*n*n, 2*n*n plot [x=-3:3] sin(x), sin(2*x), sin(x*x)Consult the gnuplot documentation to learn more about options, or to learn what mathematical functions you can use when definine your functions to plot, etc. Note: In gnuplot you don't have ^ for exponentiation!