Add a range constraint to a model. A range constraint states that the
value of the input expression must be between the specified
upper bounds in any solution.
Note that range constraints are stored internally as equality
constraints. We add an extra variable to the model to capture the
range information. Thus, the
attribute on a range
constraint will always be
lower: Lower bound for linear expression.
upper: Upper bound for linear expression.
name: Name for new constraint.
New constraint object.
# 1 <= x + y <= 2 model.addRange(x + y, 1.0, 2.0, "range0")