Data Check and Modeling Assistance

Type

Selection

Range

The settings listed below

Default

Off

This option decides whether data should be checked for consistency and whether CPLEX should offer modeling assistance. Possible values of this option are:

  • Off

  • Warn

  • Assist

When this option is set to ‘Warn’, CPLEX performs an extensive checking of data as passed to CPLEX, such as checking that indices are within range, that there are no duplicate entries, and that values are valid for the type of data or are valid numbers. This checking is useful for debugging applications.

When the value of this option is set to ‘Assist’, CPLEX turns on both data consistency checking and modeling assistance. At this level, CPLEX issues warnings at the start of the optimization about coefficients, bounds, and right-hand-side values (RHS) that are inappropriately large or small (in absolute sense). With this setting, when CPLEX solves a model then CPLEX examines features of the model that can impede performance or produce numerical instability (even if the features are otherwise valid). When CPLEX detects such detrimental or unstable features as it solves your model, it issues a warning and suggests possible improvements. For example, the following warnings are typical of such situations:

CPLEX Warning 1040: Detected a big coefficient for a binary

variable in a constraint. In constraint c171832, variable

x490416 has a coefficient 1000.21 times larger than second

largest. Consider turning constraint into an indicator.

CPLEX Warning 1041: Detected big-M constraint that could be

turned into an indicator. In constraint c8095, variable x354

has a bigM of 1000 and could be turned into indicator.

CPLEX Warning 1042: Detected a variable bound constraint with

large coefficients. Constraint c8101, links binary variable

x934 with variable x2642 and the ratio between the two is

1e+06. Consider turning constraint into an indicator for

better performance and numerical stability.

These message are printed in the Messages Window, and the CPLEX log file (if enabled).