Once the necessary inputs and formulas are entered, the optimization routine is invoked. In Excel Version 5.0 the Solver (under the Tools menu) is used. The cell to be optimized is designated (the width of the interval in this case), the type of optimization is chosen (minimize in this case), and the decision variables or variables to change are input (θ_L and θ_H here). Next the constraints shown in (3b)-(3d) are added. Once all of these are entered, the solver routine is begun, and the spreadsheet changes θ_L and θ_H until an optimal solution is reached. Once a solution is found, a sensitivity report can be generated, if desired, that will show the Lagrange multipliers.