CPLEX 11

CPLEX 11 157 GAMS/Cplex Log FileCplex reports its progress by writing to the GAMS log file as the problem solves. Normally the GAMS log file isdirected to the computer screen.The log file shows statistics about the presolve and continues with an iteration log.For the primal simplex algorithm, the iteration log starts with the iteration number followed by the scaledinfeasibility value. Once feasibility has been attained, the objective function value is listed instead. At thedefault value for option simdisplay there is a log line for each refactorization. The screen log has the followingappearance:Tried aggregator 1 time.LP Presolve eliminated 2 rows and 39 columns.Aggregator did 30 substitutions.Reduced LP has 243 rows, 335 columns, and 3912 nonzeros.Presolve time = 0.01 sec.Using conservative initial basis.Iteration log . . .Iteration: 1 Scaled infeas = 193998.067174Iteration: 29 Objective = -3484.286415Switched to devex.Iteration: 98 Objective = -1852.931117Iteration: 166 Objective = -349.706562Optimal solution found.Objective : 901.161538The iteration log for the dual simplex algorithm is similar, but the dual infeasibility and dual objective arereported instead of the corresponding primal values:Tried aggregator 1 time.LP Presolve eliminated 2 rows and 39 columns.Aggregator did 30 substitutions.Reduced LP has 243 rows, 335 columns, and 3912 nonzeros.Presolve time = 0.01 sec.Iteration log . . .Iteration: 1 Scaled dual infeas = 3.890823Iteration: 53 Dual objective = 4844.392441Iteration: 114 Dual objective = 1794.360714Iteration: 176 Dual objective = 1120.183325Iteration: 238 Dual objective = 915.143030Removing shift (1).Optimal solution found.Objective : 901.161538The log for the network algorithm adds statistics about the extracted network and a log of the network iterations.The optimization is finished by one of the simplex algorithms and an iteration log for that is produced as well.Tried aggregator 1 time.LP Presolve eliminated 2 rows and 39 columns.