Re: [Help-glpk] Branch and Bound trace

[Brady Hunsaker]

On Fri, 2004-01-30 at 11:08, Nicolo' Giorgetti wrote:
> Dear all,
> 
> Would it be possible to get some trace information of the Branch and
> Bound algorithm ? I would like to use this trace to plot the search tree
> explored by the algorithm.
> Do you know whether it is possible ?
> 
> Regards,
> Nicolo'.
> 

Nicolo',

I don't think this is currently possible for GLPK.  If you're willing to
change the code yourself, it might not be too hard (then again, it
might).  You would want to look at the function show_progress in
glpios3.c.  You may be able to modify this to show the number of the
current node and its parent.  Then you have to make sure this routine is
called at each node.  Setting the message level parameter to 3 might do
that--I'm not sure.  Otherwise you'd have to go call it each time a node
is solved.

Then you'll get a lot of output and will have to sort through the output
to recreate the b&b tree based on which node is a parent of which other
node.  It isn't too hard to automate that part of it.

Of course, everything would run a lot slower, so this is just good for
finding out about the tree.

Brady