Gnuplot and informations can be found here.
A small editor to start with Gnuplot
With this short formula you can generate a output, which you can use with gnuplot. Gnuplot is a program, that you can get from the internet for free.
You choose your desired options and then you pressOutput. In the text flied at the bottom of the document now you see a text, who the orders for gnuplot contain. You copy the text. The copied text now inserted in a editor. This will be saved as a normal textfile e. g. my_plot.dem.
This file you can open with gnuplot either with help of a menu or with the order load 'my_plot.dem'. Eventually you must change the directory, if gnuplot and my_plot.dem are not in the same directory. To do this use cd 'directory'.