The old-school Unix way of generating graphs from numeric data. It has very verbose documentation, but unfortunately it lacks in practical examples.
By default, gnuplot creates X11 windows and draws the graphs to your XServer. But that's no good for embedding it into a report, so do:
set output "filename.ps" set term postscript color [...] plot [your plot command]
If you use LaTeX, you can get gnuplot to output a LaTeX picture instead of embedding a graphic in your report:
set output "foo.tex" set term latex [...] plot [your plot command]
Note that your latex file should "\usepackage{latexsym}" so that it knows about several shapes that gnuplot outputs (such as \Diamond and \Box). Try "help set term latex" for more info.
The default is to give a function that calculates "y" for various values of "x", but that makes it difficult to get a vertical line. Do
set parametric # vertical line plot 0, t # horizontal plot t, 0 # or just plain old plot 5
set pointsize 2 # plot [xrange] [yrange] function, function, .... # do columns 3,4 and 6, using the first column for x plot [0:2] [0:100] "input" using 1:3 with linespoints title "3rd", \ "input" u 1:4 w lp t "4th", "input" u 1:6 w lp t "6th"
As you see, command names can be shortened, which can make it hard to understand what is happening :)
One page links to GnuPlot: