The NEOS Server offers Ipopt for the solution of nonlinear programming
in GAMS format. IPOPT
Documentation for GAMS/CoinIpopt is available in PDF format.
Using the NEOS Server with GAMS/CoinIpopt
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 $echo
An option file can be used to specify CoinIpopt options. Currently, the NEOS
Server can only use optfile=1 with GAMS input. Therefore, any model
that specifies a different options file will not work as intended.
The NEOS Server initially limits the amount of output generated in the
listing file by turning off the symbol and unique element list, symbol
cross references, and restricting the rows and columns listed to zero.
This behavior can be changed by specifying the appropriate options
in the model file. See the
documentation on the
modeling language for further information.
You can submit an optimization problem specified in the GAMS
modeling language to be solved using the optimization tools on
the NEOS Server. You need to specify the absolute path to a
GAMS file on your system.
The Options file is optional and requires that the
<modelname>.optfile = 1 ;
exist before the solve statement in your model file. At this
optfile = 1 is supported; however,
options may also be specified within the model input file (see
the GAMS documentation).
Optional GDX file for inputs. This file will be renamed to in.gdx. The model must include "$GDXIN in.gdx" to load this 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.
Dry run: generate job XML instead of submitting it to NEOS
Short Priority: submit to higher priority queue with maximum CPU time of 5
Please do not click the 'Submit to NEOS' button more than once.