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2 Solving Math Programs with LINGO

2.1 Introduction

The process of solving a math program requires a large number of calculations and is, therefore, best performed by a computer program. The computer program we will use is called LINGO. The main purpose of LINGO is to allow a user to quickly input a model formulation, solve it, assess the correctness or appropriateness of the formulation based on the solution, quickly make minor modifications to the formulation, and repeat the process. LINGO features a wide range of commands, any of which may be invoked at any time. LINGO checks whether a particular command makes sense in a particular context. LINGO is available in two versions: 1) a Windows-specific version, and 2) a generic, text-based version. The text-based version runs under most popular operating systems, including Unix and Linux. For either version, additional information is available to the user under the Help menu item or Help command. The Windows commands are covered briefly here. After the commands section, we will show you how to enter and solve a simple model.

2.2 LINGO for Windows

When LINGO for Windows starts, it opens a blank window known as a Model Window. The Model Window is where you “do all your work”. Output in LINGO is displayed in a Report Window. LINGO can generate a number of reports pertaining to your model. The following is a list of all the commands that are available to you, mainly in the model window.

2.2.1 File Menu

NEW F2 Use the NEW command from the File menu, press F2, or use the button to create a new Model window. In the Model window, you can enter your model.

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Chapter 2 Solving Math Programs with LINGO

OPEN F3 Use the OPEN command from the File menu, press F3, or use the button to open an existing file, typically a model file. SAVE F4 Use the SAVE command from the File menu, press F4, or use the button to save the active (frontmost) window. You can save any window — Model, Report, or Command— in...