How big a problem can AMPL solve?
Certain low-cost versions of AMPL have built-in limits on problem size. The student edition bundled with the AMPL book is limited to 300 variables and a total of 300 objectives and constraints, for example, and several packages having higher limits are offered by AMPL vendors. The professional edition of AMPL has no intrinsic limit on problem size, however; it is limited only by the resources available to the computer that is running AMPL. In practice, memory is most often the limiting resource. The amount of memory used by AMPL necessarily depends on the numbers of variables and constraints, and on the number and complexity of the terms in the constraints — or in the case of linear programs, on the number of nonzero coefficients in the constraints. Memory use also depends on the size and complexity of the model’s sets and parameters. AMPL’s presolve phase may require additional memory to execute (though it may accomplish problem reductions that allow savings of memory later). AMPL’s
