Re: [Help-glpk] Fwd: glpk help

[Robbie Morrison]

Hello Sajal

You could certainly achieve your task using the C
interface to GLPK.  I program in C++ and have a class
that holds five objective functions.  Before calling my
solver member function (aka method), I nominate one of
the five to be the active objective and later calculate
the value of the remaining four after the solver has
returned. Now that is not exactly what you asked about,
but it does share similarities.

I am guessing here, but you could try some background
scripting in your preferred scripting language (bash,
perl, python, ruby) and write out new data files on the
fly.  The GLPK wikibook has some material on scripting
and GLPSOL:

  http://en.wikibooks.org/wiki/GLPK

Or, again guessing, you could take a hybrid approach
and use a GLPK scripting language binding (python, R).

The approach you select is probably a mater of which
tools and languages you feel most comfortable with.

Can I echo Andrew's comment about using a more
descriptive subject line.  It makes it easier for
people who want to later scan thru the archives.

Good luck, Robbie

> ------------------------------------------------------------
> To:           address@hidden
> Subject:      [Help-glpk] Fwd:  glpk help
> From:         Sajal Mukhopadhyay <address@hidden>
> Date:         Mon, 5 Mar 2012 17:16:43 +0530
> ------------------------------------------------------------
>
> No answer of this message yet. Please help.
>
> ---------- Forwarded message ----------
> From: Sajal Mukhopadhyay <address@hidden>
> Date: Mon, Mar 5, 2012 at 12:20 AM
> Subject: Re: [Help-glpk] glpk help
> To: Andrew Makhorin <address@hidden>
>
> I have seen the gmpl.pdf and the problem is solved to some extent. Thank
> you again. Now I am facing another problem.
>
> I am trying to solve multiobjective solid transportation problem. I am
> using some goal programming technique. In this case what I have to do is to
> find out optimal solution of the first objective and based on the x[i,j,k]
> found in this case we have to find out the value of the other objective
> function. Next we have to find out the optimal solution of the next
> objective and based on x[i,j,k] found we have find out the value of the
> other objectives and so on.
>
> Now my problem is say I have found the values of the x[i,j,k] for finding
> the optimal value of the first objective. Now I have to calculate the value
> of the other objectives based on this x[i,j,k]. How can I do that in the
> same program. Say my program name is glp1.mod. My question is can I do that
> in the same program or I have to write a separate program. May be my
> problem is explained properly. Please help me again.
>
> On Thu, Feb 23, 2012 at 5:37 PM, Andrew Makhorin <address@hidden> wrote:
>
>> >       I am new to glpk. I want to represent c[i,j,k] for some
>> > transportation problem concerning the fact that the depot i serving
>> > customer j  with vehicle k. How can i represent the table in this
>> > environment. All code example, so far found by me, dealing with only
>> > c[i,j]. Please help me.
>>
>> Please see the MathProg language reference (doc/gmpl.pdf) and example
>> models (examples/*.mod) included in the glpk distribution. In
>> particular, see the example model train.mod; it includes
>> multidemensional parameters and variables.
>>
>> In the future please use a more descriptive subject line for your
>> messages. Thanks.
>
> --
> Sajal Mukhopadhyay,
> Asst. Professor,
> NIT,Durgapur,
> Durgapur-9.
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> ------------------------------

---
Robbie Morrison
PhD student -- policy-oriented energy system simulation
Technical University of Berlin (TU-Berlin), Germany
University email (redirected) : address@hidden
Webmail (preferred)           : address@hidden
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