Re: [Help-glpk] Copy of problem

[François Galea]

Hi,

address@hidden a écrit :
> > There is some function of
> > GLPK to create a  #8220;copy #8221; of the problem I am using?
> >  Something like LPX*copy_prob=lpx_copy_problem(original_prob);
> >
> > I need to restore the
> > original problem several times...
>
> Please see the following message:
>
> http://lists.gnu.org/archive/html/help-glpk/2003-08/msg00023.html

I have downlaoded the provided file some time ago. The GLPK API has 
changed a bit since this source code was released, hence it doesn't 
compile on recent releases of GLPK.

I have attached an updated version, which compiles smoothly with GLPK 4.13.


/* lpx_copy_prob */

#include <stddef.h>
#include "glpk.h"

LPX *lpx_copy_prob(LPX *orig)
{     /* create a copy of given problem object */
      LPX *copy;
      int m, n, i, j, type, stat, *ind, len, clss;
      double lb, ub, *val;
      /* create a copy */
      copy = lpx_create_prob();
      /* problem name */
      lpx_set_prob_name(copy, lpx_get_prob_name(orig));
      /* problem class */
      clss = lpx_get_class(orig);
      lpx_set_class(copy, clss);
      /* rows */
      m = lpx_get_num_rows(orig);
      lpx_add_rows(copy, m);
      for (i = 1; i <= m; i++)
      {  /* row name */
         lpx_set_row_name(copy, i, lpx_get_row_name(orig, i));
         /* type and bounds */
         lpx_get_row_bnds(orig, i, &type, &lb, &ub);
         lpx_set_row_bnds(copy, i, type, lb, ub);
         /* current status */
         lpx_get_row_info(orig, i, &stat, NULL, NULL);
         lpx_set_row_stat(copy, i, stat);
      }
      /* columns */
      n = lpx_get_num_cols(orig);
      lpx_add_cols(copy, n);
      for (j = 1; j <= n; j++)
      {  /* column name */
         lpx_set_col_name(copy, j, lpx_get_col_name(orig, j));
         /* column kind */
         if (clss == LPX_MIP)
            lpx_set_col_kind(copy, j, lpx_get_col_kind(orig, j));
         /* type and bounds */
         lpx_get_col_bnds(orig, j, &type, &lb, &ub);
         lpx_set_col_bnds(copy, j, type, lb, ub);
         /* objective coefficient */
         lpx_set_obj_coef(copy, j, lpx_get_obj_coef(orig, j));
         /* current status */
         lpx_get_col_info(orig, j, &stat, NULL, NULL);
         lpx_set_col_stat(copy, j, stat);
      }
      /* objective name */
      lpx_set_obj_name(copy, lpx_get_obj_name(orig));
      /* objective sense */
      lpx_set_obj_dir(copy, lpx_get_obj_dir(orig));
      /* constant term of the objective */
      lpx_set_obj_coef(copy, 0, lpx_get_obj_coef(orig, 0));
      /* constraint matrix */
      ind = ucalloc(1+m, sizeof(int));
      val = ucalloc(1+m, sizeof(double));
      for (j = 1; j <= n; j++)
      {  len = lpx_get_mat_col(orig, j, ind, val);
         lpx_set_mat_col(copy, j, len, ind, val);
      }
      ufree(ind);
      ufree(val);
      return copy;
}

/* eof */