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  1. #include <iostream>
  2. #include <iomanip>
  3. #include <cmath>
  4. using namespace std;
  5.  
  6. // Function definition
  7. double f(double x) {
  8.     return 2 * x * x * x + 3 * x - 1;
  9. }
  10.  
  11. int main() {
  12.     double x1, x2, x0, f1, f2, f0;
  13.     double E = 1e-8;
  14.     int i = 0;
  15.  
  16.     cout << "Enter the value of x0: ";
  17.     cin >> x1;
  18.     cout << "\nEnter the value of x1: ";
  19.     cin >> x2;
  20.  
  21.     f1 = f(x1);
  22.     f2 = f(x2);
  23.  
  24.     if (f1 * f2 > 0) {
  25.         cout << "\nInvalid interval. f(x0) and f(x1) must have opposite signs.\n";
  26.         return 0;
  27.     }
  28.  
  29.     cout << "\n-------------------------------------------------------------";
  30.     cout << "\nIteration\t x0\t\t x1\t\t x2\t\t f0\t\t f1\t\t f2";
  31.     cout << "\n-------------------------------------------------------------\n";
  32.  
  33.     do {
  34.         i++;
  35.         x0 = (x1 + x2) / 2;
  36.         f0 = f(x0);
  37.  
  38.         cout << fixed << setprecision(6);
  39.         cout << setw(3) << i << "\t\t"
  40.              << x0 << "\t" << x1 << "\t" << x2 << "\t"
  41.              << f0 << "\t" << f1 << "\t" << f2 << endl;
  42.  
  43.         if (f1 * f0 < 0) {
  44.             x2 = x0;
  45.             f2 = f0;
  46.         } else {
  47.             x1 = x0;
  48.             f1 = f0;
  49.         }
  50.  
  51.     } while (fabs((x2 - x1) / x2) > E);
  52.  
  53.     cout << "\nApproximate root = " << x0 << endl;
  54.  
  55.     return 0;
  56. }
  57.  
Success #stdin #stdout 0.01s 5288KB
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stdin
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-1 
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stdout
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Enter the value of x0: 
Enter the value of x1: 
Invalid interval. f(x0) and f(x1) must have opposite signs.
https://ideone.com/6qjPkt
language:
C++ (gcc 8.3)
created:
16 days ago
visibility:
public

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