Originally posted by: limetree

Hi,

I'm trying to work with cplex opl and facing several errors. I read the manual and googled but I still have no idea what I should do to fix this errors due to lacking of knowledge.

I thinking I have problems with the expression, constraints, and the data reading part.

I was wondering if anyone can help or give me ideas to figure this out. I really need your help.

Thanks.

ex1.mod

// parameters

int n = 100; // number of students
int m = 5; // number of shools
int k = 5; // number of buses
int C_vehicle = 500; // vehicle cost
int C_fuel = 2; // fuel cost
float T = 216.61; // time limit
int N = 100; // number of nodes
int t_max_k = 60; // ???
int c_max_k = 30; // ???

range student = m+1..n+m;
range school = 1..m;
range school_and_student = 1..n+m;
range bus = 1..k;
range float time = 1..T;
range node = 1..N;

 // variables
 
dvar float+ x[school_and_student][school_and_student][bus];
dvar float+ y[bus];
dvar float+ t[school_and_student][school_and_student];
dvar float+ z[student][bus][node];
dvar float+ d[node][bus];
dvar float+ c[bus];
 
 // expression
 
maximize C_vehicle * (k - sum(k in bus) y[k]) + 
C_fuel * (T - sum(i in school_and_student, j in school_and_student, k in bus) 
(t[i][j] * x[i][j][k]));

 // constraints
 
subject to {
        forall(j in student)
          allocation_bus_1:
          sum(k in bus, i in school_and_student) x[i][j][k] == 1;
          
        forall(i in student)
          allocation_bus_2:
          sum(k in bus, j in school_and_student) x[i][j][k] == 1;
          
        forall(j in school, k in bus)
          node_bus_allocation_1:
          sum(i in school_and_student) x[i][j][k] <= 1;
          
        forall(i in school, k in bus)
          node_bus_allocation_2:
          sum(j in school_and_student) x[i][j][k] <= 1;
          
        forall(j in school, k in bus)
          node_arrival_departure:
          sum(i in school_and_student) x[i][j][k] == sum(i in school_and_student) x[i][j][k];
          
        forall(i in school, j in school, k in bus)
          node_not_same:
          x[i][j][k] == 0;
          
        forall(i in school_and_student, j in student, k in bus)
          node_bus_service_arrival:
          sum(n in node) z[j][k][n] <= x[i][j][k];
        
        forall(i in school_and_student, j in student, k in bus)
          node_bus_service_departure:
          sum(n in node) z[j][k][n] <= x[j][i][k];   
          
        forall(i in student, k in bus)
          node_bus_once:
          sum(n in node) z[i][k][n] == 1;
          
        forall(j in school_and_student, n in node, k in bus)
          node_student_destination_1:
          sum(i in student) z[i][k][n] <= m * x[j][k][n];  
          
        forall(n in node, k in bus)
          node_student_destination_2:
          sum(i in student) z[i][k][n] <= m * y[k];    
          
        forall(n in node, k in bus)
          demand:
          d[n][k] == sum(j in student) (d[j][k] * z[j][k][n]); 
          
        forall(i in school_and_student, j in school_and_student, k in bus)
          time_limit_1:
          t[i][k] + t[i][j] * x[i][j][k] <= t[j][k];
          
        forall(i in school_and_student, j in school, k in bus) // i??
          time_limit_2:
          t[i][k] + t[i][j] * x[i][j][k] <= t_max_k;
          
        forall(k in bus)
          capacity_limit_1:
          c[k] <= c_max_k;
          
        forall(i in school_and_student, j in student, k in bus)
          student_node_bus_1:
          x[i][j][k] == 0 || x[i][j][k] == 1;
        
        forall(j in student, k in bus, n in node)
          student_node_bus_2:  
          z[j][k][n] == 0 || z[j][k][n] == 1;
          
        forall(i in school_and_student, k in bus)
          positive_value:  
          t[i][k] >= 0;
          c[k] >= 0;    
}

ex1.dat

SheetConnection data("data.xlsx");
t from SheetRead(data,"time!A1:DA105");

Hi,

you have some errors with indexes plus some products that are not allowed.

I remove some constraints and

 

// parameters

int n = 100; // number of students
int m = 5; // number of shools
int k = 5; // number of buses
int C_vehicle = 500; // vehicle cost
int C_fuel = 2; // fuel cost
float T = 216.61; // time limit
int N = 100; // number of nodes
int t_max_k = 60; // ???
int c_max_k = 30; // ???

range student = m+1..n+m;
range school = 1..m;
range school_and_student = 1..n+m;
range bus = 1..k;
range float time = 1..T;
range node = 1..N;

 // variables
 
dvar float+ x[school_and_student][school_and_student][bus];
dvar float+ y[bus];
dvar float+ t[school_and_student][school_and_student];
dvar float+ z[student][bus][node];
dvar float+ d[node][bus];
dvar float+ c[bus];

 
 // expression
 
maximize C_vehicle * (k - sum(k in bus) y[k]) +
C_fuel * (T - sum(i in school_and_student, j in school_and_student, k in bus)
(t[i][j] * x[i][j][k]));

 // constraints
 
subject to {
        forall(j in student)
          allocation_bus_1:
          sum(k in bus, i in school_and_student) x[i][j][k] == 1;
          
        forall(i in student)
          allocation_bus_2:
          sum(k in bus, j in school_and_student) x[i][j][k] == 1;
          
        forall(j in school, k in bus)
          node_bus_allocation_1:
          sum(i in school_and_student) x[i][j][k] <= 1;
          
        forall(i in school, k in bus)
          node_bus_allocation_2:
          sum(j in school_and_student) x[i][j][k] <= 1;
          
        forall(j in school, k in bus)
          node_arrival_departure:
          sum(i in school_and_student) x[i][j][k] == sum(i in school_and_student) x[i][j][k];
          
        forall(i in school, j in school, k in bus)
          node_not_same:
          x[i][j][k] == 0;
          
        forall(i in school_and_student, j in student, k in bus)
          node_bus_service_arrival:
          sum(n in node) z[j][k][n] <= x[i][j][k];
        
        forall(i in school_and_student, j in student, k in bus)
          node_bus_service_departure:
          sum(n in node) z[j][k][n] <= x[j][i][k];   
          
        forall(i in student, k in bus)
          node_bus_once:
          sum(n in node) z[i][k][n] == 1;
          
        forall(j in school_and_student, n in node, k in bus)
          node_student_destination_1:
         sum(i in student) z[i][k][n] <= m * x[j][n][k];  
          
        forall(n in node, k in bus)
          node_student_destination_2:
          sum(i in student) z[i][k][n] <= m * y[k];    
          
//        forall(n in node, k in bus)
//          demand:
//          d[n][k] == sum(j in student: j in node) (d[j][k] * z[j][k][n]);
          
//        forall(i in school_and_student, j in school_and_student, k in bus)
//          time_limit_1:
//          t[i][k] + t[i][j] * x[i][j][k] <= t[j][k];
          
//        forall(i in school_and_student, j in school, k in bus) // i??
//          time_limit_2:
//          t[i][k] + t[i][j] * x[i][j][k] <= t_max_k;
          
        forall(k in bus)
          capacity_limit_1:
          c[k] <= c_max_k;
          
        forall(i in school_and_student, j in student, k in bus)
          student_node_bus_1:
          x[i][j][k] == 0 || x[i][j][k] == 1;
        
        forall(j in student, k in bus, n in node)
          student_node_bus_2:  
          z[j][k][n] == 0 || z[j][k][n] == 1;
          
        forall(i in school_and_student, k in bus)
          positive_value:  
          t[i][k] >= 0;
          c[k] >= 0;    
}

works better but is not feasible.

Should you decision variables be float or integer ?

regards