Re: [Help-glpk] GLPK Problem

[vijay patil]

Miguel,

Following are some of the mistakes in your program.

> lpx_set_row_name(lp,1,"p");
> lpx_set_row_bnds(lp,1, LPX_UP , 0.0 , 100.0);
> lpx_set_row_name(lp,1,"q");
>  lpx_set_row_bnds(lp,1, LPX_UP , 0.0 , 600.0);

[1]. You are not incrementing row index, in both cases its 1. There
are similar mistake elsewhere in the program. Make sure that you
increment row index and column index.

>  lpx_set_row_bnds(lp,1, LPX_FX , 0.0 , 400.0);

[2]. Here both lower bound and upper bound should be 400.0. Refer GLPK
documentation and see usage of above function.

I hope you will be able to fix the program. You can print and verify
the LP model using function :

        /* Verify LP file. */
        lpx_write_cpxlp(lp, "output.lp");

I had some spare time, so I wrote the complete program, see
attachment, but only after you try fixing it yourselves first.



On 7/15/07, miguel montoya <address@hidden> wrote:
> Hello everybody, i want to solve the following problem
>
> Maximize Z=10x1+6x2+4x3
> Subject to
> x1+x2+x3+<=100
> 10x1+4x2+5x3<=600
> 2x1+2x2+6x3<=300
> 8x1+3x2+5x3=400
> 5x1+4x2+8x3=600
>
> where all variables are non-negative
>
> this is the routine in C
>
> LPX *lp
> int ia[1+1000], ja[1+1000];
> double ar[1+1000],Z,x1,x2,x3;
> lp=lpx_create_prob();
> lpx_set_obj_dir(lp,LPX_MAX),
> lpx_add_rows(lp,5);
> lpx_set_row_name(lp,1,"p");
> lpx_set_row_bnds(lp,1, LPX_UP , 0.0 , 100.0);
> lpx_set_row_name(lp,1,"q");
>  lpx_set_row_bnds(lp,1, LPX_UP , 0.0 , 600.0);
> lpx_set_row_name(lp,1,"r");
>  lpx_set_row_bnds(lp,1, LPX_UP , 0.0 , 300.0);
> lpx_set_row_name(lp,1,"s");
>  lpx_set_row_bnds(lp,1, LPX_FX , 0.0 , 400.0);
> lpx_set_row_name(lp,1,"t");
>  lpx_set_row_bnds(lp,1, LPX_FX , 0.0 , 600.0);
> lpx_add_cols(lp,3);
> lpx_set_col_name(lp,1,"x1");
> lpx_set_col_bnds(lp,1,LPX_LO, 0.0, 0.0);
> lpx_set_obj_coef(lp,1,10.0);
> lpx_set_col_name(lp,2,"x2");
>  lpx_set_col_bnds(lp,2,LPX_LO, 0.0, 0.0);
>  lpx_set_obj_coef(lp,1,6.0);
> lpx_set_col_name(lp,3,"x3");
>  lpx_set_col_bnds(lp,3,LPX_LO, 0.0, 0.0);
>  lpx_set_obj_coef(lp,3,4.0);
> ia[1]=1, ja=[1]=1, ar[1]=1.0;
> ia[2]=1, ja=[2]=2, ar[2]=1.0 ;
> ia[3]=1, ja=[3]=3, ar[3]=1.0 ;
> ......................................
> .....................................
> ......................................
> ........................................
> lpx_load_matrix(lp,12,ia,ja,ar);
>
> I want to know if the routine in C is right ????????????
>
> Thanks
>
> --
>
>
> _______________________________________________
> Help-glpk mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/help-glpk


--
Vijay Patil

mm-main.c
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