Information about CPLEX and AMPL
CPLEX is free for students and academics
Follow
this link.
You can run CPLEX in standalone mode, or you can call it from
C or C++ or Matlab or Python.
If you are an RPI student, you may be able to get our 2008 version of AMPL
to work with the current version of CPLEX.
Background information and reading
AMPL
is a mathematical programming and optimization modeling language
which can be used to solve linear, integer, and nonlinear
programming problems.
You can input your model into AMPL in a reasonably intuitive
way and it will use a solver (such as MINOS or CPLEX) for solving
the problem.
It is capable of solving linear, nonlinear, and integer programs.
The AMPL website
contains the
whole of the AMPL book,
a collection of
frequently asked questions,
and a list of
all the cplex options available in AMPL.
The student version of AMPL
The AMPL website
contains
downloadable executables
for use in Windows or in Unix/Linux systems, including Mac OSX.
These executables are limited in the size of problems they can solve.
Note that if you use the command line interface with Windows
and you use Word to create and edit the files, Word will add txt to
the end of a filename when stored as a text file.
For example, if your model is called zoff.mod and you created it and
stored it using Word, the file will be called zoff.mod.txt.
To read it into AMPL, you will need to use the command
ampl: model zoff.mod.txt;
Size-unrestricted versions of AMPL and CPLEX
Our current version is CPLEX 11, as of May 2008.
You must have an RPI account to be able to use the size-unrestricted versions.
The access.ilm file included in the distribution no longer works.
Consequently, you cannot currently run AMPL or CPLEX by
following the instruction below.
Installing AMPL and CPLEX on your personal computer:
Our license now allows you to
install the size-unrestricted versions of
these programs on your own machine.
Once you've installed the programs in Windows XP,
you run them from a command prompt window.
In Linux or in Mac OS X, they run in a terminal window.
The program OPL is also available, as an alternative to AMPL.
OPL is an ILOG modelling language and environment that has a user
interface that is more user-friendly than AMPL.
You can even run them from off-campus as long as you have
Cisco VPN
running.
To use the size-unrestricted version of AMPL on RCS, you need to follow
these instructions.
IBM Academic Initiative
CPLEX is an IBM product, so it can be obtained through the
IBM Academic Initiative.
After registering, you will be able to download the latest version
of CPLEX.
As of version 12, CPLEX is multithreaded.
A downloaded version of CPLEX can either be run as a stand-alone program
or called from other software written in C or C++ or Matlab, for example.
More on solvers
AMPL is a modelling language. It uses other packages to
actually solve optimization problems.
The default solver we have available on campus is
CPLEX.
Our current version of CPLEX will solve integer, linear, and
convex quadratic programming problems.
As of June 15, 2006, it can solve quadratically
constrained problems, including quadratically constrained
integer programs.
Here is some more information about working with
AMPL.
The NEOS Server
AMPL can also be run
remotely
on the NEOS server.
You submit your model and data files and it will give you the solution.
Examples:
Web resources and hints
John Mitchell