GAMS/PATH User Guide Version 4.3

problem is restarted from the initial point supplied in the GAMS file with
a different set of options. These restarts give the flexibility to change the
algorithm in the hopes that the modified algorithm leads to a solution. The
ordering and nature of the restarts were determined by empirical evidence
basedupontestsperformedonreal-worldproblems.
The exact options set during the restart are given in the restart log, part
of which is reproduced below.
Restart Log
proximal_perturbation 0
crash_method none
crash_perturb yes
nms_initial_reference_factor 2
proximal_perturbation 1.0000e-01
If a particular problem solves under a restart, a modeler can circumvent the
wasted computation by setting the appropriate options as shown in the log.
Note that sometimes an option is repeated in this log. In this case, it is the
last option that is used.
2.1.6 Solution Log
A solution report is now given by the algorithm for the point returned. The
first component is an evaluation of several different merit functions. Next, a
display of some statistics concerning the final point is given. This report can
be used detect problems with the model and solution as detailed in Chapter 3.
At the end of the log file, summary information regarding the algorithm’s
performance is given. The string “** EXIT - solution found.” is an indication
that PATH solved the problem. Any other EXIT string indicates a
termination at a point that may not be a solution. These strings give an
indication of what modelstat and solstat will be returned to GAMS. After
this, the “Restarting execution” flag indicates that GAMS has been restarted
and is processing the results passed back by PATH.
2.2 Status File
If for some reason the PATH solver exits without writing a solution, or the
sysout flag is turned on, the status file generated by the PATH solver will
be reported in the listing file. The status file is similar to the log file, but
27