Microsoft Office Tutorials and References
In Depth Information
Solver is a fairly complex software program. This section helps you address common problems you may
encounter when attempting to run Solver.
Using Whole Numbers in Changing Cells
Before you run your first Solver model or rerun a previous model, always enter a positive whole number in
each of the Changing Cells. If you have not already defined maximum and minimum constraints for the
values in the Changing Cells, enter 1 in each cell before running Solver.
Getting Negative or Fractional Answers
If you receive negative or fractional answers when running Solver, you may have neglected to specify one or
more of the Changing Cells as non-negative integers. Alternatively, if you are working on a cost minimization
problem and you fail to specify the Optimization Cell as non-negative, you may receive a negative answer for
the cost. Sometimes Solver will also warn you that you have one or more unbounded constraints (see
Solver has an “unbounded” objective function because you did not specify non-negative integer
Creating Overconstrained Models
If Solver cannot find a solution because it cannot meet the constraints you defined, you will receive an error
message. When this happens, Solver may even violate the integer constraints you defined in an attempt to
find an answer, as shown in Figure D-50.