Post-processing Graphics

gnuplot can also be used for graphical displays long after execution has terminated. The user parameters gptri, gpsol, and gpconv can be used to request that data files be produced with information about the triangulation ( gptri.dat), solution ( gpsol.dat), and convergence history ( gpconv.dat), respectively. These files are suitable for input to gnuplot . The directory mgghat/graphics contains examples of how to input these files into gnuplot to produce post-processing graphics. The files of the form whatever.gps are gnuplot scripts, or command files. They can be invoked by entering the command load `whatever.gps' at the gnuplot prompt. The following scripts are provided:

contour.gps

Contour plot of the solution.

facets.gps

The solution as facets.

solution.gps

Surface plot of the solution.

triangle.gps

The triangulation.

sol_and_tri.gps

The solution and triangulation on one plot.

converge.gps

Convergence graph of nodes vs. energy error and error estimate.

These scripts are intended to be illustrative examples of how to use gnuplot for post-processing, and are not all inclusive. They are not necessarily compatible with each other, i.e., you might have to exit gnuplot and restart it before loading a second script.

The sample data in this directory is what you should get by running the Poisson example with iorder = 2, gptri = 1, gpconv = 1, and gpsol = 20.