[Help-glpk] Question SImplex

[Jonata Goulart]

I don't know what is happening with my model.
I need to specify binarie (0, 1) variables but on the solution they are not 
integer. The model is simple (Set Covering problem). Each row has to be 
covered by at least one column.

Look what I made and the result:
Z = 4; x1 = 0; x2 = 0; x3 = 0.5; x4 = 0; x5 = 0; x6 = 0.5; x7 = 0.5
x8 = 1
thanks.

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

int main(void)
{     LPI *lp;
     double Z, valx, dx,  x1, x2, x3, x4, x5, x6, x7, x8;
     int i, tagx;

s1:   lp = glp_create_prob("scp1");

s2:   glp_new_col(lp, "x1"), glp_set_obj_coef(lp, 1, 1.0);
s3:   glp_new_col(lp, "x2"), glp_set_obj_coef(lp, 2, 2.0);
s4:   glp_new_col(lp, "x3"), glp_set_obj_coef(lp, 3, 2.0);
s5:   glp_new_col(lp, "x4"), glp_set_obj_coef(lp, 4, 2.0);
s6:   glp_new_col(lp, "x5"), glp_set_obj_coef(lp, 5, 1.0);
s7:   glp_new_col(lp, "x6"), glp_set_obj_coef(lp, 6, 1.0);
s8:   glp_new_col(lp, "x7"), glp_set_obj_coef(lp, 7, 1.0);
s9:   glp_new_col(lp, "x8"), glp_set_obj_coef(lp, 8, 2.0);

     for (i = 1; i <= 8; i ++) {
         s105: glp_set_col_kind(lp, i, 'I');
         s10: glp_set_col_bnds(lp, i, 'D', 0, 1);
     }

s11:   glp_new_row(lp, "p");
s12:   glp_set_row_bnds(lp, 1, 'L', 1.0, 0.0);
s13:   glp_new_aij(lp, 1, 1, 0.0);
s14:   glp_new_aij(lp, 1, 2, 0.0);
s15:   glp_new_aij(lp, 1, 3, 0.0);
s16:   glp_new_aij(lp, 1, 4, 0.0);
s17:   glp_new_aij(lp, 1, 5, 1.0);
s18:   glp_new_aij(lp, 1, 6, 1.0);
s19:   glp_new_aij(lp, 1, 7, 1.0);
s20:   glp_new_aij(lp, 1, 8, 0.0);

s21:   glp_new_row(lp, "q");
s22:   glp_set_row_bnds(lp, 2, 'L', 1.0, 0.0);
s23:   glp_new_aij(lp, 2, 1, 1.0);
s24:   glp_new_aij(lp, 2, 2, 0.0);
s25:   glp_new_aij(lp, 2, 3, 0.0);
s26:   glp_new_aij(lp, 2, 4, 0.0);
s27:   glp_new_aij(lp, 2, 5, 0.0);
s28:   glp_new_aij(lp, 2, 6, 1.0);
s29:   glp_new_aij(lp, 2, 7, 0.0);
s30:   glp_new_aij(lp, 2, 8, 1.0);

s31:   glp_new_row(lp, "r");
s32:   glp_set_row_bnds(lp, 3, 'L', 1.0, 0.0);
s33:   glp_new_aij(lp, 3, 1, 0.0);
s34:   glp_new_aij(lp, 3, 2, 0.0);
s35:   glp_new_aij(lp, 3, 3, 1.0);
s36:   glp_new_aij(lp, 3, 4, 0.0);
s37:   glp_new_aij(lp, 3, 5, 0.0);
s38:   glp_new_aij(lp, 3, 6, 0.0);
s39:   glp_new_aij(lp, 3, 7, 1.0);
s40:   glp_new_aij(lp, 3, 8, 0.0);

s41:   glp_new_row(lp, "s");
s42:   glp_set_row_bnds(lp, 4, 'L', 1.0, 0.0);
s43:   glp_new_aij(lp, 4, 1, 1.0);
s44:   glp_new_aij(lp, 4, 2, 1.0);
s45:   glp_new_aij(lp, 4, 3, 0.0);
s46:   glp_new_aij(lp, 4, 4, 0.0);
s47:   glp_new_aij(lp, 4, 5, 1.0);
s48:   glp_new_aij(lp, 4, 6, 1.0);
s49:   glp_new_aij(lp, 4, 7, 0.0);
s50:   glp_new_aij(lp, 4, 8, 1.0);


s51:   glp_new_row(lp, "t");
s52:   glp_set_row_bnds(lp, 5, 'L', 1.0, 0.0);
s53:   glp_new_aij(lp, 5, 1, 0.0);
s54:   glp_new_aij(lp, 5, 2, 0.0);
s55:   glp_new_aij(lp, 5, 3, 0.0);
s56:   glp_new_aij(lp, 5, 4, 0.0);
s57:   glp_new_aij(lp, 5, 5, 0.0);
s58:   glp_new_aij(lp, 5, 6, 0.0);
s59:   glp_new_aij(lp, 5, 7, 0.0);
s60:   glp_new_aij(lp, 5, 8, 1.0);


s61:   glp_new_row(lp, "u");
s62:   glp_set_row_bnds(lp, 6, 'L', 1.0, 0.0);
s63:   glp_new_aij(lp, 6, 1, 0.0);
s64:   glp_new_aij(lp, 6, 2, 0.0);
s65:   glp_new_aij(lp, 6, 3, 1.0);
s66:   glp_new_aij(lp, 6, 4, 1.0);
s67:   glp_new_aij(lp, 6, 5, 1.0);
s68:   glp_new_aij(lp, 6, 6, 1.0);
s69:   glp_new_aij(lp, 6, 7, 0.0);
s70:   glp_new_aij(lp, 6, 8, 0.0);


s71:   glp_new_row(lp, "v");
s72:   glp_set_row_bnds(lp, 7, 'L', 1.0, 0.0);
s73:   glp_new_aij(lp, 7, 1, 0.0);
s74:   glp_new_aij(lp, 7, 2, 0.0);
s75:   glp_new_aij(lp, 7, 3, 1.0);
s76:   glp_new_aij(lp, 7, 4, 0.0);
s77:   glp_new_aij(lp, 7, 5, 1.0);
s78:   glp_new_aij(lp, 7, 6, 0.0);
s79:   glp_new_aij(lp, 7, 7, 1.0);
s80:   glp_new_aij(lp, 7, 8, 0.0);


s81:   glp_new_row(lp, "x");
s82:   glp_set_row_bnds(lp, 8, 'L', 1.0, 0.0);
s83:   glp_new_aij(lp, 8, 1, 1.0);
s84:   glp_new_aij(lp, 8, 2, 0.0);
s85:   glp_new_aij(lp, 8, 3, 1.0);
s86:   glp_new_aij(lp, 8, 4, 0.0);
s87:   glp_new_aij(lp, 8, 5, 1.0);
s88:   glp_new_aij(lp, 8, 6, 0.0);
s89:   glp_new_aij(lp, 8, 7, 1.0);
s90:   glp_new_aij(lp, 8, 8, 0.0);


s91:  glp_set_obj_sense(lp, '-');

s92:  glp_simplex2(lp, NULL);

s93:  Z = glp_get_obj_val(lp);
s94:  glp_get_col_soln(lp, 1, NULL, &x1, NULL);
s95:  glp_get_col_soln(lp, 2, NULL, &x2, NULL);
s96:  glp_get_col_soln(lp, 3, NULL, &x3, NULL);
s97:  glp_get_col_soln(lp, 4, NULL, &x4, NULL);
s98:  glp_get_col_soln(lp, 5, NULL, &x5, NULL);
s99:  glp_get_col_soln(lp, 6, NULL, &x6, NULL);
s100:  glp_get_col_soln(lp, 7, NULL, &x7, NULL);
s101:  glp_get_col_soln(lp, 8, NULL, &x8, NULL);

s102:  printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g; x4 = %g; x5 = %g; x6 = 
%g; x7 = %g x8 = %g\n", Z, x1, x2, x3, x4, x5, x6, x7, x8);

s104:  glp_delete_prob(lp);

return 0;
}

/* eof */


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