XpressMP

The NEOS Server offers XPRESS-MP, from Dash Associates, for the solution of integer programming problems that can be modeled in GAMS format.

Using the NEOS Server with GAMS/XPRESS

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:

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

If you are unfamiliar with GAMS, the GAMS Tutorial 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 an alphabetical index is also available.

You may optionally submit an options file if you wish to override the default parameter settings for XPRESS. Notes on setting options to XPRESS for GAMS are available from the GAMS solvers web site. 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.

For information on Dash products and services, contact them at one of the following addresses:

Dash Optimization    
Blisworth House    		
Church Lane        		
Blisworth                       
Northants NN7 3BX
UK.
Phone: +44 (0) 1604 858 993     
Fax:   +44 (0) 1604 858 147     

560 Sylvan Avenue
Englewood Cliffs, New Jersey 07632
USA.
Phone: (201) 313-5297
Fax:   (201) 313-5299
info@dashoptimization.com

An email address is required for any submissions to XPRESS solvers. This email address will be forwarded to Dash Associates and may be used by Dash Optimization for promotional purposes.

You can submit an optimization problem specified in the GAMS modeling language to be solved using the optimization tools on the NEOS Server. You need to specify the absolute path to a GAMS file on your system.
Model 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).
Options File:

The log file contains information generated by the algorithm during a solve. Checking the box will cause the log file to be included in the output returned.
Return log file:

An email address is required for any submissions to XPRESS solvers. This email address will be forwarded to Dash Associates and may be used by Dash Optimization for promotional purposes. NEOS results will not be sent to this address.
Email Address:

Enter any additional comments here (e.g. to identify the data for your own information). These comments will be returned with your results.
Comments:

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e-mail address:

Please do not click the 'Submit to NEOS' button more than once.

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