TIle next step is to set up the constraints of the problems by clicking Add in the
Solver Parameters dialogue box. The Add Constraint dialogue box will be displayed
(see the bottom of Figure 2.12) to facilitate entering the elements of the constraints
(left-hand side, inequality type, and right-hand side) ass
$D$6:$D$9=0
Another way to enter the nonnegative constraintsis to click Options on the Solver Parameters dialogue box to access the Solver Options dialogue box (see Figure 2.13) and
then check r;;r AssumeNon-Negative. While you are in the Solver Options box, you
also need to check r;;r Assume Linear Model.
In general, the remaining defaultsettingsin Solver Options need not be changed.
However, the default precision of .000001 may be set too "high" for some problems,
and Solver may return the message "Solver could not find a feasible solution" when in
fact the problem does have a feasible solution. In such cases, the precision needs to be
adjusted to reflect less precision.Ifthe same message persists, then the problemmay be
infeasible.