NEOS Interfaces to MINOS

Sample Submissions


The NEOS Server offers MINOS for the solution of nonlinearly constrained optimization problems. Problems can be submitted to MINOS on the NEOS server in AMPL or GAMS format.

MINOS is designed to solve "smooth" nonlinear programming (NLP) problems. Smooth nonlinear functions can be accommodated in both the objective and the constraints; nonlinear equation systems may also be solved by omitting an objective. Nonsmooth nonlinearities are also accepted, but MINOS is not designed for them and in general will not produce reliable results when they are present. MINOS also offers a primal simplex method for linear programming (LP) problems.

MINOS is suitable for large constrained problems with a linear or nonlinear objective function and a mixture of linear and nonlinear constraints. It is most efficient if the constraints are linear and there are not too many degrees of freedom.

For linear programs, MINOS uses a stable implementation of the primal simplex method. For linearly constrained problems, a reduced-gradient method is employed with quasi-Newton approximations to the reduced Hessian. For nonlinear constraints, MINOS implements a sequential linearly constrained algorithm derived from Robinson's method. Step length control is heuristic, but superlinear convergence is often achieved.

MINOS was developed by Bruce A. Murtagh and Michael Saunders.

Further details on MINOS can be found in the MINOS User's Manual.

Using the NEOS Server for MINOS/GAMS

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 GAMS Documentation includes a GAMS Tutorial and User's Guide. Examples of models in GAMS format can be found in the GAMS model library.

By default, the NEOS Server 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 GAMS output for further information.

You may optionally submit an options file if you wish to override the default parameter settings for the solver. 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.

Web Submission Form
Model File
Upload the GAMS model file.
Options File
The solver options file is optional. If provided, the statement <modelname>.optfile = 1 ; is required before the solve statement in your model file. Only optfile = 1 is supported, however, options also may be specified within the model input file (see the GAMS documentation).
Parameters File
A secondary parameters file may be uploaded to NEOS. This file is optional. Note that some settings are overwritten by NEOS default settings. (See GAMS Call and CL Parameters for more details.)
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.
GAMS Restart File
A GAMS restart file can be submitted to NEOS. (See GAMS Save and Restart for more details.)
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 GAMS listing file
Check the box to include the GAMS listing file in returned output.
Return log 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.
Enter any additional comments here (e.g. to identify the data for your own information). These comments will be returned with your results.
Additional Settings

E-Mail address:
Please do not click the 'Submit to NEOS' button more than once.