gnuplot is a free, open source plotting program that has been in wide use since 1986.
It's used as the graphics backend by many other programs, so plenty of people use gnuplot
without knowing it. If you've used Octave, Maxima, statist, gretl, or the Emacs graphing
calculator, you've already used gnuplot.
gnuplot was originally designed to visualize scientific data, but its use has expanded to
encompass every domain where sophisticated and accurate plotting is required. gnuplot
is used in science, engineering, sociology, mapping, business, finance, and computer
systems and network monitoring.
gnuplot excels at complex 3D graphing with hidden-line removal and at the rendering
of surfaces and contours. It can produce almost any type of graph imaginable (except for
pie-charts—but it can be convinced to do this, too, as we'll show later!) for a dizzying array
of output devices, and can save plots in almost any type of common file format (and some
uncommon ones). It can be installed on any type of computer system you are likely to
encounter; there are binaries available for Windows and the sources can be compiled on
most reasonably modern machines. I have compiled the latest version (4.4) of gnuplot on
both Linux and Macintosh (OS X) computers and verified that all of its advanced features are
fully available on both of these architectures. The recipes in this book that illustrate features
newly appearing in version 4.4 are marked with [new].
gnuplot can easily be automated. It has its own scripting language and can be controlled from
many general-purpose programming languages. gnuplot can also be incorporated into various
publishing and document creation workflows to help create professional books, papers, and