How to plot this function I want to plot functions (using some software, any recommendations?) that looks like this below. Could someone suggest equations of functions that would look like the graph below? 


Besides the excellent suggestions made by Johannes Kloos 

Have you tried: gnuplot (free), mathematica, matlab, ...? The functions you list could be more or less anything - how about $b(x)=(x/10)^2$, $h(x)=1+b(x)$, $g(x)=2+b(x)$, $f(x)=3+b(x)$? 

I'll add that fooplot is free, runs in a browser, and is very easy to use: 

