Some versions of LINGO limit one or more of the following model properties: total variables, integer variables, nonlinear variables, global variables and constraints. The total variable limit is on the total number of optimizable variables in your model (i.e., variables LINGO was unable to determine as being fixed at a particular value). The integer variable limit applies to the total number of optimizable variables restricted to being integers with either the @BIN or @GIN functions. The nonlinear variable limit applies to the number of optimizable variables that appear nonlinearly in the model’s constraints. As an example, in the expression: X + Y, both X and Y appear linearly. However, in the expression: X ^ 2 + Y, X appears nonlinearly while Y appears linearly. Thus, X would count against the nonlinear variable limit. In some cases, nonlinear variables are allowed only if you have purchased the nonlinear option for your LINGO software. The global variable limit is the limit on the number of nonlinear variables when the global solver is used.  The constraint limit refers to the number of formulas in the model that contain one or more optimizable variables. Keep in mind that a single @FOR function may generate many constraints.

The maximum sized problem your LINGO can handle depends on the version you have. The current limits for the various versions are:

You can also determine the limits of your version by selecting the About LINGO command from the Help menu in Windows, or by typing HELP at the command-line prompt on other platforms. If you determine you need a larger version of LINGO, upgrades are available from LINDO Systems. Please feel free to contact us for pricing and availability.