GAMS: Modeling and Optimization Software
The General Algebraic Modeling System (GAMS release 2.25) is a software
system designed for modeling linear, nonlinear and mixed integer
optimization problems. The system, available on Strauss and Mahler,
is especially useful for large
complex models. GAMS allows you to model problems in a highly compact
and natural way. After formulating the model, you can easily invoke
several solvers to determine the solution to the problem. GAMS also
provides an easy-to-use report writer to display the results of the
solver in a useful format. At the University of Delaware, you can
use any of three solvers:
- BDMLP: a built-in linear programming solver
- MINOS: the widely-used Modular In-core Nonlinear Optimization System
- ZOOM: an integrated Zero-One Optimization Method and XMP
implementation for solving mixed-integer problems.
How to Run GAMS
- Construct a GAMS model by typing the GAMS commands into a file having
the filename extension ".gms". For example, a transportation model
might be stored in a file named transport.gms. The library of on-line
sample models is described in a subsequent section.
- To run GAMS on this model, type
gams "filename"
where "filename" is replaced by the name of the file without the .gms
extension. For the transport.gms example, type
gams transport
- The output file will have the extension ".lst". For the transport.gms
example, the output file is named transport.lst.
(The "gams" command is stored in the directory /opt/bin.)
The GAMS Sample Model Library
The GAMS documentation describes approximately 100 models that serve as
examples of simple and complex linear, nonlinear, and mixed integer
formulations. These are stored on-line and can be copied and modified if
you know either the name or the reference number of the model. For
example, there is a blending problem known by the name "blend" and the
reference number 47, in the GAMS printed documentation. To copy this
model to your current working directory, type either of the following:
gamslib blend
or
gamslib 47
(The "gamslib" command is stored in the directory "/opt/bin".)
Additional Documentation
- The on-line documentation is in the directory /opt/lib/gams/doc.
- gamsinfo is a general introduction to the package.
- gams.doc is a complete description of the commands and optional
keywords that can be used on the command line or in the
command file.
- gamsparm.doc is a list of GAMS parameters that can be used on the
GAMS command line or included in the GAMSPARM.TXT file
to customize the default values for GAMS.
- To obtain on-line help, type
gams -h
- Before using the "man gams" command to view the man pages, you must
first add the following command to your .localenv file.
setenv MANPATH ${MANPATH}:/opt/lib/gams/doc/man
The .localenv file is a special
configuration file
(dotfile) like .cshrc and .login
that is stored in your home directory.
- The manual for the package is "GAMS: A User's Guide", by A. Brooke and
A. Meeraus. It is available from the University Bookstore and the
User Services Reference Library (in the RDMS Lab, 002c Smith Hall).
Last modified: February 3, 2002
This page maintained by
Richard Sacher.
Copyright (c) University of Delaware, 2002
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