NEOS Server Home

NEOS Interfaces to Ipopt

WWW Form & Sample Submissions


The NEOS Server offers IPOPT for the solution of nonlinear programs in AMPL format. IPOPT is an open source software package for large-scale nonlinear optimization. It implements a primal-dual interior point algorithm, which uses a filter line search method to ensure global convergence.

IPOPT was developed by Andreas Wächter, Lorenz T. Biegler, Arvind Raghunathan, and Yi-Dong Lang. For more information, see the IPOPT home page. A list of papers and publications describing the algorithm is available here.

Using the NEOS Server with IPOPT

The user must submit a model in AMPL format to solve a nonlinear programming problem. The examples section of the AMPL website provides examples of models in AMPL format.

The nonlinear programming problem must be specified by a model file with the options of a data file and a commands file. If the commands file is specified, it must contain the AMPL solve command. The commands file must not contain the model or data commands. The model and data files are renamed internally by NEOS.

The commands file may include AMPL commands and option settings for IPOPT. To specify solver options, add

option ipopt_options "OPTIONS";
where OPTIONS is a list of one or more of the IPOPT options. See the options available via the AMPL interface.

Enter the location of the AMPL model (local file)
Model File:

Enter the location of the AMPL data file (local file)
Data File:

Enter the location of the AMPL commands file (local file)
Commands File:


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:

By submitting a job, you have accepted the Terms of Use
Please do not click the 'Submit to NEOS' button more than once.

Submit comments and questions Terms of Use