[Symphony] biobjective problems

[Papis Wongchaisuwat]

Thank you for a reply.I tried to start from simple problem that I found in presentation online.vmax [8x1, x2]s.t. 7x1 + x2 <= 5628x1 + 9x2 <= 2523x1 + 7x2 <=105x1, x2 >=0
In bicriteria.c, I use#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);
}
my lp file :Maximize 

obj: 8 var_1 + var_2

 

Subject to 

 C1: 7 var_1 + var_2 <=
56

C2: 28 var_1 + 9 var_2 <= 252

C3: 3 var_1+ 7 var_2 <= 105

Bound

var_1>=0

var_2>=0Integervar_1var_2

End 
I got incorrect results. This is what I gotFirst Objective: -64.000 Second Objective: 0.000 Range: 0.468750-1.000000First Objective: -47.000 Second Objective: -15.000 Range: 0.000000-0.468750
What did I do wrong?
Thank you,Papis


From: ted at Lehigh.EDU
Date: Sun, 15 Sep 2013 12:27:26 -0400
Subject: Re: [Symphony] biobjective problems
To: papis_31 at hotmail.com
CC: hennebry at web.cs.ndsu.nodak.edu; symphony at list.coin-or.org

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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(610) 628-1280
ted 'at' lehigh 'dot' edu
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