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Using the Interactive Graph Drawing Software
The Interactive Graph Drawing (IGD) software package is included with
SYMPHONY and SYMPHONY facilitates its use through interfaces with the
package. The package, which is a Tcl/Tk application, is extremely
useful for developing and debugging applications involving graph-based
problems. Given display coordinates for each node in the graph, IGD
can display support graphs corresponding to fractional solutions with or
without edge weights and node labels and weights, as well as other
information. Furthermore, the user can interactively modify the graph
by, for instance, moving the nodes apart to ``disentangle'' the
edges. The user can also interactively enter violated cuts through the
IGD interface.
To use IGD, you must have installed PVM since the drawing window runs
as a separate application and communicates with the user's routines
through message passing. To compile the graph drawing application,
type ``make dg'' in the SYMPHONY root directory. The user
routines in the file user_dg.c can be filled in, but it is not
necessary to fill anything in for basic applications.
After compiling dg, the user must write some subroutines that
communicate with dg and cause the graph to be drawn.
Regrettably, this is currently a little more complicated than it needs
to be and is not well documented. However, by looking at the sample
application, it should be possible to see how it is done. To
enable graph drawing, put the line do_draw_graph 1 into the
parameter file or use the -d command line option. It can be difficult to
get IGD to work. If you are interested in using it and cannot get it to work,
feel free to contact me.
Next: Other Debugging Techniques
Up: Debugging Your Application
Previous: Checking the Validity of
Ted Ralphs
2003-10-16