Re: [Help-glpk] Passing arguments instead of an input file

[Fábio Moura]

Hi, Marc.

I had already seen this code. The problem is that the model we are
implementing is a huge one, full of details and lots of different
variables and creating it in memory would be a probably impossible
task in the near future. Is it the only way, though?

Maybe, instead of an text input file, I could pass a string (with the
same contents)? I would have to rewrite some code, but could be it
easier... Does anyone have tried it before?

Best regards!

FM




On Thu, Jun 12, 2008 at 5:42 PM, Meketon, Marc
<address@hidden> wrote:
> See "sample.c" in the "examples" directory for a technique to create the 
> problem in memory and pass it to GLPK.
>
> Below is a cut and paste of "sample.c":
>
> /* sample.c */
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <glpk.h>
>
> int main(void)
> {     glp_prob *lp;
>      int ia[1+1000], ja[1+1000];
>      double ar[1+1000], z, x1, x2, x3;
> s1:   lp = glp_create_prob();
> s2:   glp_set_prob_name(lp, "sample");
> s3:   glp_set_obj_dir(lp, GLP_MAX);
> s4:   glp_add_rows(lp, 3);
> s5:   glp_set_row_name(lp, 1, "p");
> s6:   glp_set_row_bnds(lp, 1, GLP_UP, 0.0, 100.0);
> s7:   glp_set_row_name(lp, 2, "q");
> s8:   glp_set_row_bnds(lp, 2, GLP_UP, 0.0, 600.0);
> s9:   glp_set_row_name(lp, 3, "r");
> s10:  glp_set_row_bnds(lp, 3, GLP_UP, 0.0, 300.0);
> s11:  glp_add_cols(lp, 3);
> s12:  glp_set_col_name(lp, 1, "x1");
> s13:  glp_set_col_bnds(lp, 1, GLP_LO, 0.0, 0.0);
> s14:  glp_set_obj_coef(lp, 1, 10.0);
> s15:  glp_set_col_name(lp, 2, "x2");
> s16:  glp_set_col_bnds(lp, 2, GLP_LO, 0.0, 0.0);
> s17:  glp_set_obj_coef(lp, 2, 6.0);
> s18:  glp_set_col_name(lp, 3, "x3");
> s19:  glp_set_col_bnds(lp, 3, GLP_LO, 0.0, 0.0);
> s20:  glp_set_obj_coef(lp, 3, 4.0);
> s21:  ia[1] = 1, ja[1] = 1, ar[1] =  1.0; /* a[1,1] =  1 */
> s22:  ia[2] = 1, ja[2] = 2, ar[2] =  1.0; /* a[1,2] =  1 */
> s23:  ia[3] = 1, ja[3] = 3, ar[3] =  1.0; /* a[1,3] =  1 */
> s24:  ia[4] = 2, ja[4] = 1, ar[4] = 10.0; /* a[2,1] = 10 */
> s25:  ia[5] = 3, ja[5] = 1, ar[5] =  2.0; /* a[3,1] =  2 */
> s26:  ia[6] = 2, ja[6] = 2, ar[6] =  4.0; /* a[2,2] =  4 */
> s27:  ia[7] = 3, ja[7] = 2, ar[7] =  2.0; /* a[3,2] =  2 */
> s28:  ia[8] = 2, ja[8] = 3, ar[8] =  5.0; /* a[2,3] =  5 */
> s29:  ia[9] = 3, ja[9] = 3, ar[9] =  6.0; /* a[3,3] =  6 */
> s30:  glp_load_matrix(lp, 9, ia, ja, ar);
> s31:  glp_simplex(lp, NULL);
> s32:  z = glp_get_obj_val(lp);
> s33:  x1 = glp_get_col_prim(lp, 1);
> s34:  x2 = glp_get_col_prim(lp, 2);
> s35:  x3 = glp_get_col_prim(lp, 3);
> s36:  printf("\nz = %g; x1 = %g; x2 = %g; x3 = %g\n",
>         z, x1, x2, x3);
> s37:  glp_delete_prob(lp);
>      return 0;
> }
>
> /* eof */
>
> -----Original Message-----
> From: address@hidden [mailto:address@hidden On Behalf Of Fábio Moura
> Sent: Thursday, June 12, 2008 4:39 PM
> To: address@hidden
> Subject: [Help-glpk] Passing arguments instead of an input file
>
> Ladies and Gentlemen,
>
> I'm programming a C/C++ application with the GLPK API and I'm
> currently using the function
>
> LPX *lpx_read_model(char *model, char *data, char *output)
>
> to read and translate the model and problem data. Unfortunately, due
> to a security restriction of the system, I won't be able to write an
> input file with the problem data and, therefore, "feed" my problem
> instance with it (even though my code is open and I delete the input
> file right after reading it)..
>
> Does anyone know a way of passing the problem data to a problem
> instance as arguments of a function (C language)? I can't use an input
> file with the problem data...
>
> Any ideas?
>
> Thanks in advance!
>
> --
> Fábio Lucas Carneiro de Moura
>
>
> _______________________________________________
> Help-glpk mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/help-glpk
>



-- 
Fábio Lucas Carneiro de Moura