I have asked Chat GPT for the code below but it's not worked. Could you help me please 

// Number of materials and time periods
int N = 2; // Number of materials
int T = 3; // Number of periods

// Input data
float p[N][T] = [ [10, 12, 15], [8, 9, 11] ];   // Unit cost of materials
float s[N][T] = [ [5, 5, 5], [3, 3, 3] ];       // Setup cost
float h[N][T] = [ [2, 2, 2], [1, 1, 1] ];       // Inventory holding cost
float d[N][T] = [ [20, 15, 10], [10, 5, 8] ];   // Production demand
float r[N] = [1, 1];                            // Resource usage per material
float C[T] = [30, 25, 20];                      // Maximum resource capacity per period
float M = 1000;                                 // Large constant for linking constraints

// Decision variables
dvar float+ x[N][T];   // Quantity purchased of material i in period t
dvar float+ I[N][T];   // Inventory level of material i at the end of period t
dvar boolean Y[N][T];  // Binary variable: 1 if material i is purchased in period t, otherwise 0

// Objective function: Minimize total costs
minimize 
  sum(i in 0..N-1, t in 0..T-1) (p[i][t] * x[i][t] + s[i][t] * Y[i][t] + h[i][t] * I[i][t]);

// Constraints
subject to {
  // 1. Balance supply and demand
  forall(i in 0..N-1, t in 0..T-1) {
    if (t == 0) // Initial period
      x[i][t] - I[i][t] == d[i][t];
    else // Subsequent periods
      I[i][t-1] + x[i][t] - I[i][t] == d[i][t];
  }
  
  // 2. Resource capacity constraints
  forall(t in 0..T-1)
    sum(i in 0..N-1) r[i] * x[i][t] <= C[t];
  
  // 3. Linking constraint between x and Y
  forall(i in 0..N-1, t in 0..T-1)
    x[i][t] <= M * Y[i][t];
}

Hello Thuận,

       You can declare two ranges:

• range rangeN = 0..N-1;
• range rangeT = 0..T-1;

and replace N by rangeN and T by rangeT for input data and decision variables.

Best regards,