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Re: [Help-glpk] Parametric studies in GMPL?

From: Jeffrey Kantor
Subject: Re: [Help-glpk] Parametric studies in GMPL?
Date: Fri, 9 Jul 2010 15:48:34 -0400

Hi Marc,

Exactly.  I appreciate Xypron's suggestion, but would much prefer to embed the logic directly in GMPL.  Seems to me even an elementary ability to loop and introduce conditionals in the solution process would open a wide range of applications to GMPL/GLPK.  


On Fri, Jul 9, 2010 at 3:43 PM, Meketon, Marc <address@hidden> wrote:
This reminds me that at the very top of my "wish" list for GLPK is a control language for GMPL.  Something to experiment with various decomposition methods, column generation, and so on.


-----Original Message-----
From: [] On Behalf Of glpk xypron
Sent: Friday, July 09, 2010 3:37 PM
To: Jeffrey Kantor; address@hidden
Subject: Re: [Help-glpk] Parametric studies in GMPL?

Hello Jeffy,

you can use a shell script.

Here is a minimalistic example. Save the following as file test.awk

modfile = "test.mod";
datfile = "test.dat";
system("rm " modfile);
printf ("Writing model file\n");
printf ("#model file\n") > modfile;
printf ("param iter;\n") > modfile;
printf ("solve;\n") > modfile;
printf ("display iter;\n") > modfile;
printf ("end;\n") > modfile;
for (i = 1; i <= 10; i++) {
 system("rm " datfile);
 printf("\n\nIteration %i\n",i);
 printf ("Writing data file\n");
 printf("#data file %i\n", i) > datfile;
 printf("data;\n") > datfile;
 printf("param iter := %i;\n", i) > datfile;
 printf("end;\n") > datfile;
 system("glpsol -m " modfile " -d " datfile);

Run the script with

awk -f test.awk

Windows users can find a binary for awk at
For Windows replace "rm " by "del ".

Please, observe that glpsol allows multiple data files,
so you could have one with the changing parameter and another
with the rest of your model data.

Best regards


-------- Original-Nachricht --------
> Datum: Fri, 9 Jul 2010 09:15:19 -0400
> Betreff: [Help-glpk] Parametric studies in GMPL?

> Hi --
> I'd like to be able to parametric studies in GMPL.  In other words, do a
> simple loop over a range of parameter values with the solve statement
> inside
> the loop.  To the best of my knowledge this is not currently possible, or
> is
> it?  If not, could this be a feature that could be incorporated into GMPL
> at
> some point?
> Jeff

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