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

[Meketon, Marc]

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.

-Marc

-----Original Message-----
From: address@hidden [mailto:address@hidden 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

BEGIN {
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;
close(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;
  close(datfile);
  system("glpsol -m " modfile " -d " datfile);
  }
exit;
}


Run the script with

awk -f test.awk

Windows users can find a binary for awk at 
http://gnuwin32.sourceforge.net/packages/gawk.htm
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

Xypron

-------- 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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