CODEWITHSUNDEEP
cplexopl
Aziz Agasi
Aziz Agasi

Reputation: 63

Cplex showing value of decision variables as 0

So I am solving a transportation optimization model with some changes on my own. The model runs successfully but when I see the values of the decision variables it showing me a 3D array with all values as 0.

.mod file

int m = ...;
int n = ...;
int o = ...;

range I = 1..m;
range J = 1..n;
range K = 1..o;

float d[I][J] = ...;
float s[I] = ...;
float f = ...;
float v = ...;
float q = ...;
float u[I][J][K];

dvar float x[I][J][K];
dvar int y[I][J][K];

float data[1..9][1..261] = ...;

minimize sum(i in I, j in J, k in K) f*y[i][j][k] + sum(i in I, j in J, k in K) v*d[i][j]*y[i][j][k];

subject to {
  Constraint1: forall(j in J, k in K) sum(i in I) x[i][j][k] == sum(i in I) u[i][j][k];
  
  Constraint2: forall(i in I) sum(j in J, k in K) x[i][j][k] <= s[i];
  
  Constraint3: forall(i in I, j in J, k in K) x[i][j][k] <= q*y[i][j][k];
  
  Constraint4: forall(i in I, j in J, k in K) x[i][j][k] >= 0;
  Constraint5: forall(i in I, j in J, k in K) y[i][j][k] >= 0;
}

execute {
  
    for (var k = 1; k <= 3; k++) {
        for (var i = 1; i <= 3; i++) {
            for (var j = 1; j <= 261; j++) {
                // Calculate the row index based on k and i
                var row = (k - 1) * 3 + i; // 3 rows per k
                u[i][j][k] = data[row][j]; // Offset by 1 for customer index
            }
        }
    }
}

.dat file

m = 3;
n = 261;
o = 3;

SheetConnection Sheet ("ProjectData.xlsx");
d from SheetRead (Sheet, "CPLEX! C6:JC8");
s from SheetRead (Sheet, "Data! C3:C5");
f from SheetRead (Sheet, "Data! B16");
v from SheetRead (Sheet, "Data! B17");
q from SheetRead (Sheet, "Data! B18");
data from SheetRead (Sheet, "CPLEX! C16:JC24");

I have checked the values of all parameters to see if the value is correct and that is coming out to be the case. CPLEX is not giving me any reason as well why my model will not run. I am on student CPLEX version if it helps.

Upvotes: 0

Views: 22

Answers (1)

Alex Fleischer
Alex Fleischer

Reputation: 10062

I think that the issue could be that you wrote

float u[I][J][K];

which means all u are 0

int m = 3;
int n = 261;
int o = 3;

range I = 1..m;
range J = 1..n;
range K = 1..o;

float d[i in I][j in J] = rand(10);
float s[i in I] = rand(10)+200000;
float f = 2;
float v = 3;
float q = 8000;
float u[i in I][j in J][k in K]=rand(10);

dvar float x[I][J][K];
dvar int y[I][J][K];

float data[i in 1..9][j in 1..261] = rand(10);

minimize sum(i in I, j in J, k in K) f*y[i][j][k] + sum(i in I, j in J, k in K) v*d[i][j]*y[i][j][k];

subject to {
  Constraint1: forall(j in J, k in K) sum(i in I) x[i][j][k] == sum(i in I) u[i][j][k];
  
  Constraint2: forall(i in I) sum(j in J, k in K) x[i][j][k] <= s[i];
  
  Constraint3: forall(i in I, j in J, k in K) x[i][j][k] <= q*y[i][j][k];
  
  Constraint4: forall(i in I, j in J, k in K) x[i][j][k] >= 0;
  Constraint5: forall(i in I, j in J, k in K) y[i][j][k] >= 0;
}

execute {
  
    for (var k = 1; k <= 3; k++) {
        for (var i = 1; i <= 3; i++) {
            for (var j = 1; j <= 261; j++) {
                // Calculate the row index based on k and i
                var row = (k - 1) * 3 + i; // 3 rows per k
                u[i][j][k] = data[row][j]; // Offset by 1 for customer index
            }
        }
    }
}

gives a non null solution

Upvotes: 0

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