ILOG CPLEX 11.0 User's Manual

Use the scaling parameter (ScaInd, CPX_PARAM_SCAIND) to set scaling appropriate foryour model. Table 9.6 summarizes available values for this parameter.Table 9.6 ScaIndParameter Settings for Scaling MethodsScaIndValueMeaning-1 no scaling0 equilibration scaling (default)1 aggressive scalingRefactoring FrequencyILOG CPLEX dynamically decides the frequency at which the basis of a problem isrefactored in order to maximize the speed of iterations. On very large problems,ILOG CPLEX refactors the basis matrix infrequently. Very rarely should you considerincreasing the number of iterations between refactoring. The refactoring interval iscontrolled by the ReInv parameter. The default value of 0 (zero) means ILOG CPLEX willdecide dynamically; any positive integer specifies the user's chosen factoring frequency.CrashIt is possible to control the way ILOG CPLEX builds an initial (crash) basis through theCraInd parameter.In the dual simplex optimizer, the CraInd parameter sets whether ILOG CPLEXaggressively uses primal variables instead of slack variables while it still tries to preserve asmuch dual feasibility as possible. If its value is 1 (one), it indicates the default starting basis;if its value is 0 (zero) or -1, it indicates an aggressive starting basis. These settings aresummarized in Table 9.7.Table 9.7 CraInd Parameter Settings for the Dual Simplex OptimizerCraIndSettingMeaning for Dual Simplex Optimizer1 Use default starting basis guided by coefficients0 Use an aggressive starting basis ignoring coefficients-1 Use an aggressive starting basis contrary to coefficientsIn the primal simplex optimizer, the CraInd setting sets how ILOG CPLEX uses thecoefficients of the objective function to select the starting basis. If its value is 1 (one),ILOG CPLEX uses the coefficients to guide its selection; if its value is 0 (zero),182 ILOG CPLEX 11.0 — USER’ S MANUAL