Making C code plot a graph automatically.

Question

I have written a program which writes a list of data to a '.dat' file with the intention of then plotting it separately using gnuplot. Is there a way of making my code plot it automatically? My output is of the form:

x-coord    analytic    approximation
x-coord    analytic    approximation
x-coord    analytic    approximation
x-coord    analytic    approximation
x-coord    analytic    approximation
 ....

Ideally, when I run the code the graph would also be printed with an x-label, y-label and title (which could be changed from my C code). Many thanks.

Answer 1

You can either create a gnuplot script and spawn a process running gnuplot to plot this script from the commandline, or you may use one of the provided interfaces. For C, there is a POSIX pipe-based interface from Nicolas Devillard available here: http://ndevilla.free.fr/gnuplot/ ...and an iostream-based C++ version is available via git (see: http://www.stahlke.org/dan/gnuplot-iostream/ )

The most portable and probably the easiest way would still be calling gnuplot to plot a script, though. As sje397 mentioned, check your documentation for the system() call in stdlib.h.

On a sidenote, there is also GNU plotutils, which offers libplot, a library for plotting datasets, which you could use in your application. See: http://www.gnu.org/software/plotutils/