How to Call GLPK from AMPL

[Shailesh]

Hello,

  I want to use GLPK solver-glpsol within AMPL. Do you know how should I call glpsol from AMPL ?

I tried using glpsol -m ampl.mod but that failed due to the syntax error. 

Thank you.

[Indrajit Sen Gupta]

Don't think it is possible to call glpk from AMPL. If you are using glpsol, from the commandline, it will work on its own.

https://en.wikibooks.org/wiki/GLPK/Using_GLPSOL

Regards,

Indrajit

[Robert Fourer]

GLPK does not have an AMPL interface. If you can use any free solver, then try downloading CBC for AMPL from http://ampl.com/products/solvers/open-source/; CBC handles the same kinds of problems as GLPK. If you must use GLPK, you can use the AMPL command "write mampl;" to write an MPS file named ampl.mps which you can send to GLPK; however you will not be able to read GLPK's results back into AMPL to view them, so option is of limited value.

Bob Fourer
am...@googlegroups.com

=======

[Meketon, Marc]

There are several reasons why you might have a syntax error when running an AMPL model within GLPK.

 

(1)  The language in GLPK (called MathProg or GMPL) is a subset of AMPL, and lacks useful AMPL features such as node-arc modeling and command scripts (and a lot more).  See http://ampl.com/BOOK/CHAPTERS/18-network.pdf and http://ampl.com/BOOK/CHAPTERS/16-script.pdf

(2)  GMPL does differ in some details from AMPL even for the same type of statement (see, e.g., https://lists.gnu.org/archive/html/help-glpk/2005-05/msg00014.html)

 

An alternative is for you try to modify your model to fit within the GMPL.  If you get stuck, you might wish to communicate with the GLPK help group. See https://lists.gnu.org/mailman/listinfo/help-glpk

 

                                                                     

From: am...@googlegroups.com [mailto:am...@googlegroups.com] On Behalf Of Shailesh
Sent: Wednesday, January 04, 2017 6:48 PM
To: AMPL Modeling Language
Subject: [AMPL 13300] How to Call GLPK from AMPL

 

Hello,

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[Shailesh]

Thank you, Robert, Marc, and Indrajit.

   As GLPK does not have an interface with AMPL, I tried CBC solver as per your suggestion, and it works fine. As I don't have any requirement to use GLPK, I stick with CBC. However, if any necessity initiates in the future, I will re-write my model in GMPL. 

[Bence Bagi]

May I ask why you need an open-source solver when you have AMPL (and presumably the solvers available with it - that's just an assumption that you have multiple commercial solvers at hand)?