GLPK Example

mysample.c

/* mysample.c */
/* gcc -I../src -o mysample mysample.c ../src/*.o */

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

/*
minimize
	z = 14.7x1 + 10.7x2 + 7.2x4
subject to
	n0 = x1 + x2 + x4
	n2 = 3450x1 + 3300x2 + 3250x4
	n3 = 7.6x1 + 7.29x2 + 2.16x4
	n6 = 1.15x1 + 3.43x2 + 0.33x4
and bounds of variables
	2950 <= n2 < +inf 0.2 <= x1 < +inf
	   6 <= n3 <= 21 	0 <= x2 <= 0.30
	 0.5 <= n6 <= 7	 	0 <= x4 < +inf
	 n0=1
	   
*/

int main(void)
{     glp_prob *lp;
   int ia[1+1000], ja[1+1000];
   double ar[1+1000], z, x1, x2, x3;
   lp = glp_create_prob();
   glp_set_prob_name(lp, "sample");
   glp_set_obj_dir(lp, GLP_MIN);

// Constraint Nutrient Spec
  glp_add_rows(lp, 4);
  glp_set_row_name(lp, 1,"n0");
  glp_set_row_bnds(lp, 1, GLP_FX, 1,1);
  glp_set_row_name(lp, 2, "n2");
  glp_set_row_bnds(lp, 2, GLP_LO, 2950.0, 0.0);
  glp_set_row_name(lp, 3, "n3");
  glp_set_row_bnds(lp, 3, GLP_DB, 6.0, 21.0);
  glp_set_row_name(lp, 4, "n6");
  glp_set_row_bnds(lp, 4, GLP_DB, 0.5, 7.0);

// Constraint Weight of Ingredient Spec
  glp_add_cols(lp, 3);
  glp_set_col_name(lp, 1, "x1");
  glp_set_col_bnds(lp, 1, GLP_LO, 0.2, 0.0);
  glp_set_obj_coef(lp, 1, 14.7);
  glp_set_col_name(lp, 2, "x2");
  glp_set_col_bnds(lp, 2, GLP_DB, 0.0, 0.30);
  glp_set_obj_coef(lp, 2, 10.7);
  glp_set_col_name(lp, 3, "x4");
  glp_set_col_bnds(lp, 3, GLP_LO, 0.0, 0.0);
  glp_set_obj_coef(lp, 3, 7.2);

// Fill Value of nutrient for each ingredient
  ia[1] = 1, ja[1] = 1, ar[1] =  1.0; /* a[1,1] =  1 */
  ia[2] = 1, ja[2] = 2, ar[2] =  1.0; /* a[1,2] =  1 */
  ia[3] = 1, ja[3] = 3, ar[3] =  1.0; /* a[1,3] =  1 */
  ia[4] = 2, ja[4] = 1, ar[4] =  3450.0; /* a[2,1] = 3450.0 */
  ia[5] = 2, ja[5] = 2, ar[5] =  3300.0; /* a[2,2] = 3300.0 */
  ia[6] = 2, ja[6] = 3, ar[6] =  3250.0; /* a[2,3] = 3250.0 */
  ia[7] = 3, ja[7] = 1, ar[7] =  7.6; /* a[3,1] =  7.6 */
  ia[8] = 3, ja[8] = 2, ar[8] =  7.29; /* a[3,2] =  7.29 */
  ia[9] = 3, ja[9] = 3, ar[9] =  2.16; /* a[3,3] =  2.16 */
  ia[10] = 4, ja[10] = 1, ar[10] =  1.15; /* a[4,1] =  1.15 */
  ia[11] = 4, ja[11] = 2, ar[11] =  3.43; /* a[4,2] =  3.43 */
  ia[12] = 4, ja[12] = 3, ar[12] =  0.33; /* a[4,3] =  0.33 */

  glp_load_matrix(lp, 12, ia, ja, ar);
  glp_simplex(lp, NULL);
  z = glp_get_obj_val(lp);
  x1 = glp_get_col_prim(lp, 1);
  x2 = glp_get_col_prim(lp, 2);
  x3 = glp_get_col_prim(lp, 3);
  printf("\nz = %g; x1 = %g; x2 = %g; x3 = %g\n",
     z, x1, x2, x3);
  glp_delete_prob(lp);
      return 0;
}

/* eof */