Re: Nonlinear constraint in MPS format

[Michael Hennebry]

On Tue, 18 Jul 2023, Prabhu Manyem wrote:

> I have a non-linear model in AMPL format (which is very similar to
> GMPL format)... I would like to convert this to free-MPS format..
> Unfortunately,  glpsol  is unable to convert non-linear models to
> MPS.. (And the free version of AMPL which I have does NOT allow file
> conversions).
>
> The objective function is linear..  Most of the constraints are
> linear, except one constraint which is non-linear..  The single
> non-linear constraint looks like this:

My understanding is that standard MPS allows
for linear constraints and objectives only.
There are extentions allowing quadratic objectives and constraints.

> ax + b(x)(x) + c(x)(x)(x) + d/x + e/x/x + f/x/x/x = C.

I know of no extention that allows seven distinct, -3..3, powers of x.

> If we remove the constraint above, then we have an LP.

> My question -- Is it easy to edit the MPS file obtained above, and
> input the single non-linear constraint?
>
> Or, is there any other way to obtain an MPS file for the entire
> non-linear model?

No.
No.

--
Michael   hennebry@mail.cs.ndsu.NoDak.edu
"Occasionally irrational explanations are required"  --  Luke Roman