[FileFormats] Reader for NL: unsupported mode b

[matbesancon]

An example with an instance from the MINLPLib:

using JuMP

julia> m = read_from_file("portfol_shortfall200_05.nl")
ERROR: Unable to parse NL file : unsupported mode b

[odow]

Link? I think this is the binary format, which did not seem to be documented

[matbesancon]

https://www.minlplib.org/nl/portfol_shortfall200_05.nl

[matbesancon]

ping @svigerske

[odow]

Found this: https://ampl.github.io/nlwrite.pdf

I guess I can reverse engineer it...

[odow]

See #2718, it was actually pretty simple

using JuMP, Gurobi
filename = "portfol_shortfall200_05.nl"
model = read_from_file(filename; use_nlp_block = false)
set_optimizer(model, Gurobi.Optimizer)
optimize!(model)

Solve seems to be on the right track

Gurobi Optimizer version 12.0.1 build v12.0.1rc0 (mac64[x86] - Darwin 24.1.0 24B83)

CPU model: Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz
Thread count: 4 physical cores, 8 logical processors, using up to 8 threads

Optimize a model with 605 rows, 806 columns and 81608 nonzeros
Model fingerprint: 0x0483491b
Model has 2 general nonlinear constraints (402 nonlinear terms)
Variable types: 605 continuous, 201 integer (201 binary)
Coefficient statistics:
  Matrix range     [4e-07, 8e+00]
  Objective range  [1e+00, 1e+00]
  Bounds range     [1e+00, 1e+00]
  RHS range        [7e-01, 1e+01]

User MIP start did not produce a new incumbent solution
User MIP start violates constraint R0 by 1.000000000

Presolve added 1 rows and 0 columns
Presolve removed 0 rows and 1 columns
Presolve time: 0.09s
Presolved: 608 rows, 1205 columns, 81811 nonzeros
Presolved model has 400 quadratic constraint(s)
Variable types: 1004 continuous, 201 integer (201 binary)

Root relaxation: objective -1.283613e+00, 407 iterations, 0.01 seconds (0.01 work units)

    Nodes    |    Current Node    |     Objective Bounds      |     Work
 Expl Unexpl |  Obj  Depth IntInf | Incumbent    BestBd   Gap | It/Node Time

     0     0   -1.28361    0    -          -   -1.28361      -     -    0s
     0     0   -1.25012    0    -          -   -1.25012      -     -    0s

 20332 11031   -1.13534   34   27   -1.12596   -1.14412  1.61%   162  190s
 20341 11038   -1.13394   36   23   -1.12596   -1.14412  1.61%   162  198s

[matbesancon]

Thanks!