Use this parameter to set the style of derivative computation. Set DERCMP to 0 (Solver Decides) to allow LINGO to select the method, 1 for backward analytical derivatives, 2 for forward analytical derivatives, 3 for numerical derivatives using central differences, and 4 for numerical derivatives using forward differences.

LINGO defaults to the Solver Decides setting, which presently involves using backward analytical derivatives.   However, we suggest you try the various derivative options to see which works best for your particular models.