| # A two-dimensional toy optimization problem As a toy example of an optimization problem in two variables, consider the problem (Note that the term ‘‘subject to’’ has been replaced with the shorthand colon notation.) The problem can be put in standard form where: the decision variable is ; the objective function , takes values the constraint functions , take values is the optimal value, which turns out to be . See also: Geometric view of the toy problem. Nomenclature for the toy problem.