The NEOS Server offers the IBM ILOG CPLEX
Optimizer for the solution of mixed-integer linear programming (MILP) problems that can be modeled in
For information on IBM Decision Optimization products, including the
CPLEX Optimizer, visit IBM Decision Optimization.
For information on all IBM software available to academics, visit the
IBM Academic Initiative.
Using the NEOS Server with GAMS/CPLEX
The user must submit a model in GAMS
format to solve an optimization problem. For security purposes, the model
submitted must adhere to the following conventions:
If you are unfamiliar with GAMS, the
gives a quick introduction to the essentials of a GAMS model and the
output provided when the model is solved. Examples of models in GAMS
format can be found in the
GAMS model library and
is also available.
- The model must be self contained, i.e. no $include or $batinclude
- No execution of external programs is allowed, i.e. no $call or execute
- No file creation, i.e. no put files or $echo
You may optionally submit an options file if you wish to override
the default parameter settings for CPLEX. Notes on
setting options to CPLEX for GAMS are available from the GAMS solvers web
Currently, the NEOS Server can only use optfile=1 with GAMS input.
Therefore, any model that specifies
a different options file will not work as intended.
The NEOS Server initially limits the amount of output generated in the
listing file by turning off the symbol and unique element list, symbol
cross references, and restricting the rows and columns listed to zero.
This behavior can be changed by specifying the appropriate options
in the model file. See the
documentation on the
modeling language for further information.
Note: An email address is required for any submissions
that use CPLEX. This email address will be forwarded to IBM
and may be used by IBM for promotional purposes.
If using the XML-RPC interface, you must add the line <email>firstname.lastname@example.org</email> into the XML file that is sent to NEOS.