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

[Haroldo Santos]

I'm interested in something similar, I'm not quite sure if it is
possible to do in GMPL, but it would certainly be nice:

Consider that you have a problem to solve, which is too hard
considering MIP capabilities.

I would like to do, in GMPL, some (heuristic) like:

Split problem P into P1, P2 ...  Pn
Solve P1
Solve P2
....
Solve Pn
merge solution of P1  ... Pn to provide a solution to P

Is there any way to do it ?

Thanks,

Haroldo



On Fri, Jul 9, 2010 at 4:48 PM, Jeffrey Kantor <address@hidden> wrote:
> 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.
> Jeff
>
> 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.
>>
>> -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
>>
>> --
>> GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT!
>> Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01
>>
>> _______________________________________________
>> Help-glpk mailing list
>> address@hidden
>> http://lists.gnu.org/mailman/listinfo/help-glpk
>>
>> ----------------------------------------------------------------------------
>> This e-mail and any attachments may be confidential or legally privileged.
>>  If you received this message in error or are not the intended recipient,
>> you should destroy the e-mail message and any attachments or copies, and you
>> are prohibited from retaining, distributing, disclosing or using any
>> information contained herein.  Please inform us of the erroneous delivery by
>> return e-mail.
>>
>> Thank you for your cooperation.
>>
>> ----------------------------------------------------------------------------
>>
>
>
> _______________________________________________
> Help-glpk mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/help-glpk
>
>



-- 
=============================================================
Haroldo Gambini Santos
Computing Department - Universidade Federal de Ouro Preto - UFOP
email: haroldo [at ] iceb.ufop.br
home/research page: http://www.iceb.ufop.br/decom/prof/haroldo/

"Computer science is no more about computers than astronomy
is about telescopes." Edsger Dijkstra