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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int main()
  5. {
  6.     int n;
  7.     cout << "Enter number of data points: ";
  8.     cin >> n;
  9.  
  10.     double x[n], y[n][n];
  11.  
  12.     // Input x values
  13.     cout << "Enter x values:\n";
  14.     for (int i = 0; i < n; i++)
  15.     {
  16.         cin >> x[i];
  17.     }
  18.  
  19.     // Input y values
  20.     cout << "Enter y values:\n";
  21.     for (int i = 0; i < n; i++)
  22.     {
  23.         cin >> y[i][0];
  24.     }
  25.  
  26.     // Difference table (nested loop)
  27.     for (int j = 1; j < n; j++)
  28.     {
  29.         for (int i = 0; i < n - j; i++)
  30.         {
  31.             y[i][j] = y[i + 1][j - 1] - y[i][j - 1];
  32.         }
  33.     }
  34.  
  35.     // Print difference table (optional)
  36.     cout << "\nForward Difference Table:\n";
  37.     for (int i = 0; i < n; i++)
  38.     {
  39.         for (int j = 0; j < n - i; j++)
  40.         {
  41.             cout << y[i][j] << "\t";
  42.         }
  43.         cout << endl;
  44.     }
  45.  
  46.     double value;
  47.     cout << "\nEnter value to interpolate: ";
  48.     cin >> value;
  49.  
  50.     double h = x[1] - x[0];
  51.     double p = (value - x[0]) / h;
  52.  
  53.     double result = y[0][0];
  54.     double term = 1;
  55.  
  56.     // Forward interpolation calculation (another loop)
  57.     for (int i = 1; i < n; i++)
  58.     {
  59.         term = term * (p - (i - 1)) / i;
  60.         result += term * y[0][i];
  61.     }
  62.  
  63.     cout << "\nInterpolated value at x = " << value << " is: " << result << endl;
  64.  
  65.     return 0;
  66. }
Success #stdin #stdout 0.01s 5292KB
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stdin
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Standard input is empty
stdout
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Enter number of data points: Enter x values:
Enter y values:

Forward Difference Table:

Enter value to interpolate: 
Interpolated value at x = 6.95282e-310 is: 8.69103e-311
https://ideone.com/wq3TPy
language:
C++ (gcc 8.3)
created:
15 hours ago
visibility:
public

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