Microsoft Office Tutorials and References
In Depth Information
Other Solver options
Note that when Excel converts numbers to integers, the program effectively rounds down;
the decimal portion of the number is truncated. The integer solution shows that by placing
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Determine whether you need integer constraints
Adding integer constraints to a Solver problem can geometrically increase the
problem’s complexity, resulting in possibly unacceptable delays. The example discussed
in this chapter is relatively simple and does not take an inordinate amount of time to
solve, but a more complex problem with integer constraints might pose more of a
challenge for the Solver. The Solver can solve certain problems only by using integer
constraints. In particular, integer solutions are useful for problems in which variables can
assume only two values, such as 1 or 0 (yes or no), but if you’re looking for “yes or no”
results, you can also use the bin (binary) option in the list in the middle of the Change
Constraint dialog box.
Other Solver options
In the Solver Parameters dialog box, the Select A Solving Method drop-down list offers
three options: GRG Nonlinear (the default), Simplex LP, and Evolutionary. Simply put, here
are the differences:
GRG Nonlinear The default solving method is optimized for “smooth nonlinear”
problems involving points along a curved (but smooth) line.
Simplex LP This method works best for linear problems that can be defined as
points along a straight line.
Evolutionary This option works best when your model involves “non-smooth,”
or random, discontinuous elements that would not plot along either a straight or
curved line.
Click the Options button in the Solver Parameters dialog box to display the Options dialog
box shown in Figure 18-28, which contains many additional settings. It’s best to leave the
options on the GRG Nonlinear and Evolutionary tabs at their default settings—unless you
understand linear optimization techniques. The following options on the All Methods tab
warrant some explanation:
The Constraint Precision setting determines how closely you want values in the
constraint cells to match your constraints. The closer this setting is to the value 1, the
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