If you don't know JavaPlot, it's a Java library which 'connects' Java with the popular gnuplot providing a set of classes. When it runs, it searches for the gnuplot binary in your system. Anyway, some months ago I've been through the awful experience of installing gnuplot under Mac OS and now all my data are gone, so gnuplot is not on my system anymore. If you don't know JavaPlot, it's a Java library