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Glpk

The NEOS Server offers Glpk, the GNU Linear Programming Kit, for the solution of integer programming problems that can be modeled in GAMS format through the COIN-OR/GAMSlinks project.

Documentation for GAMS/CoinGlpk is available in PDF format.


Using the NEOS Server with GAMS/CoinGlpk

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.

An option file can be used to specify CoinGlpk options. 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. 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:


Optional GDX file for inputs. This file will be renamed to in.gdx. The model must include "$GDXIN in.gdx" to load this file
GDX File:


The solver will return a compressed GDX file which contains all symbols in the model.
Return GDX output:


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:


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


Put in priority queue. 5 minute job runtime limit.
Dry run: generate job XML instead of submitting it to NEOS
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