[Symphony] biobjective problems

[Ted Ralphs]

sym_set_obj2_coeff(env, i, j) sets the objective function coefficient of
variable "i" to value "j" in the second objective, as documented here:

http://www.coin-or.org/SYMPHONY/man-5.5/node176.html

At the moment, setting the objective coefficients one by one is the only
way to specify a second objective through the API. Of course, you can also
just directly set the objective function in SYMPHONY's internal
representation of the instance.

I have plans to improve this and to add the ability to specify two
objectives through a modeling language, such as GMPL, but I haven't gotten
to it yet.

Cheers,

Ted


On Sat, Sep 14, 2013 at 10:58 PM, Papis Wongchaisuwat
<papis_31 at hotmail.com>wrote:

> I found  bicriteria.c file in Examples. I tried running with the data set
> and I got several solutions as I am supposed to get.
> However, I am not sure whether I got a correct result.
> These are some parts of bicriteria.c file
> #include "symphony.h"
>
> int main(int argc, char **argv)
> {
>
>    sym_environment *env = sym_open_environment();
>    sym_parse_command_line(env, argc, argv);
>    sym_load_problem(env);
>
>    sym_set_obj2_coeff(env, 1, -1);
>
>    sym_mc_solve(env);
>
>    sym_close_environment(env);
>
>    return(0);
>
> }
>
> #endif
>
> Does anyone know what sym_set_obj2_coeff(env, 1, -1) means?  When should
> I use 1 or -1?
> My sample data is a minimization problem.
>
> Thank you,
> Papis
>
> > Date: Fri, 13 Sep 2013 23:29:29 -0500
>
> > From: hennebry at web.cs.ndsu.nodak.edu
> > To: papis_31 at hotmail.com
> > CC: symphony at list.coin-or.org
> > Subject: RE: [Symphony] biobjective problems
> >
> > On Sat, 14 Sep 2013, Papis Wongchaisuwat wrote:
> >
> > > I would like to run bi-objective Set cover and Set pack problems.
> Attached files are some examples that I want to run. MCKP and these
> problems are quite different. I don't know how to apply MCKP or either use
> any other ways to run these problems.
> >
> > From reading the manual,
> > I gather one can call sym_explicit_load_problem( ... )
> > and follow it by calling sym_mc_solve( ... ) .
> > Is there a reason that you cannot do that?
> >
> > --
> > Michael hennebry at web.cs.ndsu.NoDak.edu
> > "On Monday, I'm gonna have to tell my kindergarten class,
> > whom I teach not to run with scissors,
> > that my fiance ran me through with a broadsword." -- Lily
>
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> Symphony at list.coin-or.org
> http://list.coin-or.org/mailman/listinfo/symphony
>
>


-- 
Dr. Ted Ralphs
Associate Professor, Lehigh University
(610) 628-1280
ted 'at' lehigh 'dot' edu
coral.ie.lehigh.edu/~ted
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