[Scip] Saving problem to .nl format produced by AMPL

[Ramón Casero Cañas]

Hi Stefan,

Many thanks for the overview of options. I think for us, the last one
(.osil files, and use the OS/Ipopt interface to run Ipopt) would be the
feasible one, but writing a function that outputs the problem in that XML
format is not something we can do right now. But it's good to know what we
need to do if we want to go down that route!

Cheers,

Ramon.


On 23 June 2014 23:30, Stefan Vigerske <stefan at math.hu-berlin.de> wrote:

> Hi,
>
> no, you need AMPL to produce a file in .nl format.
> And AMPL needs AMPL .mod files as input, which SCIP cannot write either.
>
> You could let SCIP write your PIP as .gms file, and then use GAMS to
> convert it to a .mod file. Or you can Ipopt via GAMS.
> But all this requires a GAMS license.
>
> If you write your .pip files by some program anyway, then you could
> probably modify it to write .mod files, too. Then with AMPL you could
> convert these into .nl files.
> Or you could write .osil files, and use the OS/Ipopt interface to run
> Ipopt. That would be an all-open-source way to do it.
>
> Stefan
>
>
> On 06/24/2014 12:20 AM, Ramón Casero Cañas wrote:
>
>> Dear all,
>>
>> Sorry for the sligh off-topic. I'd like to compare SCIP to ipopt solving a
>> problem. I see that SCIP v 3.1.0 can save to formats
>>
>>   file reader          extension  description
>>   -----------          ---------  -----------
>>   ccgreader                  ccg  file writer for column connectivity
>> graph
>> file format
>>   cipreader                  cip  file reader for CIP (Constraint Integer
>> Program) format
>>   fznreader                  fzn  file reader for FlatZinc format
>>   gmsreader                  gms  file writer for MI(NL)(SOC)Ps in GAMS
>> file
>> format
>>   lpreader                    lp  file reader for MIPs in IBM CPLEX's LP
>> file format
>>   mpsreader                  mps  file reader for MIQPs in IBM's
>> Mathematical Programming System format
>>   opbreader                  opb  file reader for pseudo-Boolean problem
>> in
>> opb format
>>   pipreader                  pip  file reader for polynomial mixed-integer
>> programs in PIP format
>>   ppmreader                  ppm  file writer for portable pixmap file
>> format (PPM), open with common graphic viewer programs (e.g. xview)
>>   pbmreader                  pbm  file writer for portable bitmap file
>> format (PBM), open with common graphic viewer programs (e.g. xview)
>>   rlpreader                  rlp  file reader for MIPs in IBM CPLEX's RLP
>> file format
>>   wboreader                  wbo  file reader for pseudoboolean wbo file
>> format
>>
>> but not to .nl, which is the format that the ipopt binary can load. Is
>> there a way to produce an .nl file from the .pip file that I use to load
>> the problem into SCIP?
>>
>> Best regards,
>>
>> Ramon.
>>
>>
>>
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>>
>>
>


-- 
Dr. Ramón Casero Cañas

Institute of Biomedical Engineering
Department of Engineering Science, University of Oxford
Old Road Campus Research Building, Headington
Oxford
OX3 7DQ
UK

tlf         +44 (0) 1865 617716
twitter   @Ramon_Casero
web      http://www.cs.ox.ac.uk/people/Ramon.CaseroCanas/
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