Tools
In order to do accurate performance evaluations for MIP models it may
be useful to obtain more detailed information about a solve than the
end data the trace file gives. We may want to have intermediate
information about the solve for the rootnode, subnodes, and end
results.
The miptrace option allows users to output detailed
solve information of best integer and best bound values for every n
nodes or at every time step. For example, the user may be interested
in the best integer and best bound every 50 nodes and every five
seconds of the solve.
Using the GAMS miptrace option
The miptrace option is invoked by specifying
miptrace (filename)
miptracetime (time step)
miptracenode (node step)
in the solver option file.
The (filename) is the miptrace file that will be created.
The optional command miptracetime specifies the time
interval, and the optional command miptracenode the node
interval.
In this case, the miptrace file will contain information
every 5 seconds and for every 50 nodes.
The default node and time increments are 100 nodes
and 1 second, respectively.
A sample miptrace file is
miptrace.mtr where the file includes statistics of
a GAMS run using the MIP model
blend2 from the Performance Library and the solver
XPRESS.
Miptrace file parameters
The column headers for miptrace files are as follows:
1. lineNum: GAMS index to be able to read in the file as a table.
2. seriesID: S=start, N=Node, T=time information, E=end.
3. node:
4. seconds: time after solve start.
5. bestFound: best integer solution at a given time or node.
6. bestBound: best bound at a given time or node.
