[Help-glpk] Help with glpk ?

[Flavio Keidi Miyazawa]

Hi,

When I try to execute the below linear program, I have the following
message:

Assertion failed: "not implemented yet" == NULL; file source/glplpx6a.c;
line 290

Since the LP is very simple, I think the problem is with my code.
Does anybody know what is happening and what is the mistake in
this code ?

Thank you,

Flavio.
---------------------------------------------------------------------------------------------------------------------

#include <stdio.h>
#include <glpk.h>

int main(void)
{
  LPX *lp;
  int ndx[1+4];
  double val[1+4];
  double Z, x1, x2, x3, x4;

  /* LP problem:

     maximize 1.x1 + 2.x2 + 3.x3 + 4.x4

     s.a.       x1 +   x2 +   x3         <= 1.0

     0 <= x1 <= 1
     0 <= x2 <= 1
     0 <= x3 <= 1
     0 <= x4 <= 1
   */

  lp = lpx_create_prob();

  lpx_add_cols(lp,4);

  lpx_set_col_bnds(lp,1,LPX_DB,0.0,1.0);
  lpx_set_col_bnds(lp,2,LPX_DB,0.0,1.0);
  lpx_set_col_bnds(lp,3,LPX_DB,0.0,1.0);
  lpx_set_col_bnds(lp,4,LPX_DB,0.0,1.0);

  lpx_add_rows(lp, 1);
  lpx_set_row_bnds(lp,1,LPX_UP,0.0,1.0);

  ndx[1]=1; val[1]=1;
  ndx[2]=2; val[2]=1;
  ndx[3]=3; val[3]=1;
  lpx_set_mat_row(lp, 1, 3, ndx, val);

  lpx_set_obj_dir(lp, LPX_MAX);

  lpx_set_col_coef(lp,1,1.0);
  lpx_set_col_coef(lp,2,2.0);
  lpx_set_col_coef(lp,3,3.0);
  lpx_set_col_coef(lp,4,4.0);

  lpx_simplex(lp);

  Z=lpx_get_obj_val(lp);
  lpx_get_col_info(lp,1,NULL,&x1,NULL);
  lpx_get_col_info(lp,2,NULL,&x2,NULL);
  lpx_get_col_info(lp,3,NULL,&x3,NULL);
  lpx_get_col_info(lp,4,NULL,&x4,NULL);

  printf("\nZ=%g; x1=%g; x2=%g; x3=%g; x4=%g\n", Z, x1, x2, x3, x4);

  lpx_delete_prob(lp);
  return(0);
}