The message indicates that the CPLEX presolve procedures has declared a model infeasible before the selected optimization algorithm begins. This early declaration saves considerable execution time in most cases. The log file will give you more information:
... Primal unbounded due to dual bounds, variable 'GFACAP(d2005.2020)'. Presolve time = 7.92 sec. Presolve found the problem infeasible or unbounded. Rerunning with presolve turned off. ...
scaind 1
) or a manual scaling (Chapter 17.3 of the GAMS User's Guide) could improve tolerance issues. You may also try to solve the model with another LP solver.GFACAP(d2005.2020)
. You may have to increase the default level for limrow (default is 3) to see the complete equation listing in the GAMS listing file.Primal unbounded …
). A more systematic approach is to set the GAMS/CPLEX option Reduce
(Default 3) to 2 which will only detect unboundedness in the presolve, while a setting of 1 will only detect infeasibility. These settings of the Reduce
parameter are intended for diagnostic use only.