An optimization model can be linear or nonlinear, depending on the form of the mathematical relationships used to model the objective and constraints. Figure 69, Comparison of linear and nonlinear relationships, following, illustrates linear and nonlinear relationships. In a linear relationship, all terms in the formulas only contain a single variable multiplied by a constant. For example, 3x - 1.2y is a linear relationship since both the first and second term only involve a constant multiplied by a variable. Terms such as x2, xy, 1/x, or 3.1x make nonlinear relationships. Any models that contain such terms in either the objective or a constraint are classified as nonlinear.
Crystal Ball can handle both linear and nonlinear objectives and constraints. For information on defining linear or nonlinear constraints, see Specifying Constraints .