Optimization Settings
Applying a LP-optimization model in forest management planning, integer solutions are sometimes of interest. A stand is usually regarded as a treatment unit to be completely treated according to a certain treatment in a certain period. This might be of certain interest when it comes to short term-planning, i.e. what to do now and in the next year - couple of years.
The most straightforward way to obtain integer solutions is to allow only integer values of the decision variable, i.e. set the range type of xi, j to "binary". However, this might lead to infeasible solutions. Another way is to round off to closest integer value (0 or 1), hence forcing the results to be a set of complete treatment programmes for each stand in the analysis area. In menu "Optimization" > "Settings...":
- The General-tab allows the user to... By selecting "Integer-round off"... Optimization results can be saved to the result database by selection or by pressing the "Discette"-button in the optimization model builder-window.
- The Lpsolve Settings-tab allows the user to... In "Mip Gap" ..., in "Time Limit"...
- The Cplex Settings-tab...
- Note
- Values, in SEK/ha, can obviously be less than zero (negative) for stands and analysis areas in one or several periods. Make sure that this variable has a "RangeType" set to "All" (and not "Default" that only allows for positive values).