The NEOS Server offers CONOPT for the solution of nonlinearly constrained
optimization problems. Problems can be submitted to CONOPT on the NEOS
server in AMPL or GAMS format.
CONOPT is a solver for general nonlinear programming models with sparse
nonlinear constraints. It is a feasible-path method based on the
GRG (generalized reduced gradient) algorithm. CONOPT is well-suited to
models with very nonlinear constraints. It is a fast method for finding an
initial feasible solution that is particularly well-suited to models with
few degrees of freedom. Also, for models where many equations can be solved
one by one, CONOPT will take advantage of this property. Similarly, CONOPT
eliminates from the model intermediate variables only used to define
objective function terms and moves the constraints into the objective
CONOPT was developed and is currently maintained by ARKI Consulting
and Development A/S in Bagsvaerdvej, Denmark. For more information, visit
the CONOPT website.
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
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.
Update: As of April 2020, NEOS will use CONOPT4 by default for GAMS models.
<modelname>.optfile = 1 ;
optfile = 1