NEOS Server Home

NEOS Interfaces to CPLEX

Sample Submissions
WWW Form - Email - XML-RPC


The NEOS Server offers the IBM ILOG CPLEX Optimizer for the solution of second order conic programming (SOCP) problems that can be modeled in GAMS format.

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 a second order cone problem (SOCP). For security purposes, the model submitted must adhere to the following conventions:

If you are unfamiliar with GAMS, the GAMS Documentation includes a GAMS Tutorial and User's Guide. Examples of models in GAMS format can be found in the GAMS model library and an alphabetical index is available.

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></email> into the XML file that is sent to NEOS.

Web Submission Form
Model File
To submit an SOCP specified in the GAMS modeling language, you need to specify the absolute path to the GAMS file on your system.
Options File
The Options file is optional and requires that the statement <modelname>.optfile = 1 ; exist before the solve statement in your model file. At this time, only optfile = 1 is supported; however, options may also be specified within the model input file (see the GAMS documentation).
GDX File
Optional GDX file for inputs. This file will be renamed to in.gdx. The model must include "$GDXIN in.gdx" to load this file
Return GDX output
Check the box to have the solver return a compressed GDX file that contains all of the symbols in the model.
Return log file
The log file contains information generated by the algorithm during a solve. Check the box to have the log file included in the output returned.
Additional Settings
Dry run: generate job XML instead of submitting it to NEOS
Short Priority: submit to higher priority queue with maximum CPU time of 5 minutes
E-Mail address:
Please do not click the 'Submit to NEOS' button more than once.