Originally posted by: vjkgp

Hi,

please go through the below program, when i run it, i am getting all my decision variables value zero,

these following error are coming,

// MILP solution error (Ax=b) (Total, Max)       0.00000e+000 0.00000e+000
// MILP x bound error (Total, Max)               0.00000e+000 0.00000e+000
// MILP x integrality error (Total, Max)         0.00000e+000 0.00000e+000
// MILP slack bound error (Total, Max)           0.00000e+000 0.00000e+000
//

help me how to remove these errors,

Model:-

{int} box={1,2,3,4,5,6,7};
{int} truck={1,2,3,4,5,6};
int length[box]=[103, 103, 103, 103, 103, 103,103];
int width[box]=[91,91,91,91,91, 91, 91];
int height[box]=[116,116,116,116,116, 116, 116];
int weight[box]=[558,558,558,558,558, 558, 558];
float len[truck]= [426.72, 426.72, 487.68, 548.64, 731.52,1219.2];
float wid[truck]=[182.88,182.88,213.36, 213.36, 213.36,243.84];
float het[truck]=[182.88,182.88,213.36, 213.36, 213.36,243.84];
int wet[truck]=[3000, 3500, 7000, 9000, 15000,20000];
 int M=10000;
dvar boolean L[box];
dvar float+ X[box];
dvar float+ Y[box];
dvar float+ Z[box];
dvar boolean A[box,box];  
dvar boolean B[box,box];
dvar boolean C[box,box];
dvar boolean D[box,box];
dvar boolean n[truck];
dvar boolean S[box,truck];


minimize
  sum(j in truck)wet[j]*n[j]-sum(i in box)weight[i];
 
subject to {
      forall(i in box, k in box : i<k)
        ct1:
          (X[i] + length[i]*L[i] + width[i]*(1-L[i])) <= (X[k] + (1-A[i,k])*M);
    forall( i in box,k in box: i<k)
        ct2:
          (X[k] + length[k]*L[k] + width[k]*(1-L[k])) <= (X[i] + (1-B[i,k])*M);        
    forall( i in box,k in box: i<k)
        ct3:
          (Y[i] + width[i]*L[i] + length[i]*(1-L[i])) <= (Y[k] + (1-C[i,k])*M);    
    forall( i in box,k in box: i<k)
        ct4:
          (Y[k] + width[k]*L[k] + length[k]*(1-L[k])) <= (Y[i] + (1-D[i,k])*M);
    forall( i in box,k in box: i<k)
        ct5:
          (Z[i] + height[i]) <= (Z[k] + M);
    forall( i in box,k in box: i<k)
        ct6:
          (Z[k] + height[k]) <= (Z[i] + M);        
    forall(i in box,k in box,j in truck : i<k)
      ct7:
        (A[i,k] + B[i,k] + C[i,k] + D[i,k])>=(S[i,j] - S[k,j] - 1);
      ct8:
        sum(j in truck) n[j]==1;
    forall(i in box)
      ct9:
        sum(j in truck) S[i,j]==1;
    forall(j in truck)
      ct10:
        sum(i in box)S[i,j]<=M*n[j];
    forall( i in box,j in truck)
        ct11:
          X[i] + length[i]*L[i] + width[i]*(1-L[i])<=len[j]*n[j] + (1-S[i,j])*M;
    forall( i in box,j in truck)      
        ct12:
          Y[i] + width[i]*L[i] + length[i]*(1-L[i])<=wid[j]*n[j] + (1-S[i,j])*M;
    forall( i in box,j in truck)        
        ct13:
          Z[i] + height[i]<=het[j]*n[j] + (1-S[i,j])*M;
    forall(i in box, j in truck)
       ct14:
        sum(i in box) weight[i]<=(wet[j]*n[j] + (1-S[i,j])*M);
}    

Thanks,

Vijendra

Hi,

your model is fine and gives

n = [0
         0 1 0 0 0];
X = [0 0 0 0 0 0 0];
L = [0 0 0 0 0 0 0];
A = [[0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]];
B = [[0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]];
Y = [0 0 0 0 0 0 0];
C = [[0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]];
D = [[0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]
             [0 0 0 0 0 0 0]];
Z = [0 0 0 0 0 0 0];
S = [[0 0 1 0 0 0]
             [0 0 1 0 0 0]
             [0 0 1 0 0 0]
             [0 0 1 0 0 0]
             [0 0 1 0 0 0]
             [0 0 1 0 0 0]
             [0 0 1 0 0 0]];

No error

regards

Originally posted by: vjkgp

Hi,

thanks but you see all the values of decision variables are zero, please see in the solution consule, there are some messages coming like

// MILP solution error (Ax=b) (Total, Max)       0.00000e+000 0.00000e+000
// MILP x bound error (Total, Max)               0.00000e+000 0.00000e+000
// MILP x integrality error (Total, Max)         0.00000e+000 0.00000e+000
// MILP slack bound error (Total, Max)           0.00000e+000 0.00000e+000
//

because of these i think values are not coming.

Hi,

most are zeros, but some are not:

S = [[0 0 1 0 0 0]

See the 1 ?

regards

Originally posted by: vjkgp

ok, tell me what should i do to get over with these following error

is there any statement by which it will not appear??......suggest me

Let me share what I see