1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
|
import org.gnu.glpk.GLPK;
import org.gnu.glpk.GLPKConstants;
import org.gnu.glpk.GlpkException;
import org.gnu.glpk.SWIGTYPE_p_double;
import org.gnu.glpk.SWIGTYPE_p_int;
import org.gnu.glpk.glp_prob;
import org.gnu.glpk.glp_iocp;
public class Mip {
// Maximize z = 17 * x1 + 12* x2
// subject to
// 10 x1 + 7 x2 <= 40
// x1 + x2 <= 5
// where,
// 0.0 <= x1 integer
// 0.0 <= x2 integer
public static void main(String[] arg) {
glp_prob lp;
glp_iocp iocp;
SWIGTYPE_p_int ind;
SWIGTYPE_p_double val;
int ret;
try {
// Create problem
lp = GLPK.glp_create_prob();
System.out.println("Problem created");
GLPK.glp_set_prob_name(lp, "myProblem");
// Define columns
GLPK.glp_add_cols(lp, 2);
GLPK.glp_set_col_name(lp, 1, "x1");
GLPK.glp_set_col_kind(lp, 1, GLPKConstants.GLP_IV);
GLPK.glp_set_col_bnds(lp, 1, GLPKConstants.GLP_LO, 0, 0);
GLPK.glp_set_col_name(lp, 2, "x2");
GLPK.glp_set_col_kind(lp, 2, GLPKConstants.GLP_IV);
GLPK.glp_set_col_bnds(lp, 2, GLPKConstants.GLP_LO, 0, 0);
// Create constraints
GLPK.glp_add_rows(lp, 2);
GLPK.glp_set_row_name(lp, 1, "c1");
GLPK.glp_set_row_bnds(lp, 1, GLPKConstants.GLP_UP, 0, 40);
ind = GLPK.new_intArray(3);
val = GLPK.new_doubleArray(3);
GLPK.intArray_setitem(ind, 1, 1);
GLPK.intArray_setitem(ind, 2, 2);
GLPK.doubleArray_setitem(val, 1, 10);
GLPK.doubleArray_setitem(val, 2, 7);
GLPK.glp_set_mat_row(lp, 1, 2, ind, val);
GLPK.glp_set_row_name(lp, 2, "c2");
GLPK.glp_set_row_bnds(lp, 2, GLPKConstants.GLP_UP, 0, 5);
GLPK.intArray_setitem(ind, 1, 1);
GLPK.intArray_setitem(ind, 2, 2);
GLPK.doubleArray_setitem(val, 1, 1);
GLPK.doubleArray_setitem(val, 2, 1);
GLPK.glp_set_mat_row(lp, 2, 2, ind, val);
GLPK.delete_doubleArray(val);
GLPK.delete_intArray(ind);
// Define objective
GLPK.glp_set_obj_name(lp, "obj");
GLPK.glp_set_obj_dir(lp, GLPKConstants.GLP_MAX);
GLPK.glp_set_obj_coef(lp, 0, 0);
GLPK.glp_set_obj_coef(lp, 1, 17);
GLPK.glp_set_obj_coef(lp, 2, 12);
// Solve model
iocp = new glp_iocp();
GLPK.glp_init_iocp(iocp);
iocp.setPresolve(GLPKConstants.GLP_ON);
ret = GLPK.glp_intopt(lp, iocp);
// Retrieve solution
if (ret == 0) {
write_mip_solution(lp);
} else {
System.out.println("The problem could not be solved");
};
// free memory
GLPK.glp_delete_prob(lp);
} catch (GlpkException ex) {
ex.printStackTrace();
ret = 1;
}
System.exit(ret);
}
/**
* write integer solution
* @param mip problem
*/
static void write_mip_solution(glp_prob lp) {
int i;
int n;
String name;
double val;
name = GLPK.glp_get_obj_name(lp);
val = GLPK.glp_mip_obj_val(lp);
System.out.print(name);
System.out.print(" = ");
System.out.println(val);
n = GLPK.glp_get_num_cols(lp);
for(i=1; i <= n; i++) {
name = GLPK.glp_get_col_name(lp, i);
val = GLPK.glp_mip_col_val(lp, i);
System.out.print(name);
System.out.print(" = ");
System.out.println(val);
}
}
}
|
