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  1. #include <iostream>
  2. #include <iomanip>
  3. #include <cmath>
  4. using namespace std;
  5.  
  6. double f(double x) {
  7.     return 2 * pow(x, 3) + 3 * x - 1;
  8. }
  9.  
  10. int main() {
  11.     double x1, x2, x0, f1, f2, f0, E;
  12.     int i = 1;
  13.  
  14.     cout << "Enter the value of x0: ";
  15.     cin >> x1;
  16.     cout << "Enter the value of x1: ";
  17.     cin >> x2;
  18.  
  19.     cout << "Enter the tolerance (E): ";
  20.     cin >> E;
  21.  
  22.     f1 = f(x1);
  23.     f2 = f(x2);
  24.  
  25.     if (f1 * f2 > 0) {
  26.         cout << "Invalid interval! f(x0) and f(x1) must have opposite signs.\n";
  27.         return 0;
  28.     }
  29.  
  30.     cout << "\nIteration\t" 
  31.          << "x0\t\t" << "x1\t\t" << "x2\t\t"
  32.          << "f0\t\t" << "f1\t\t" << "f2" << endl;
  33.  
  34.     do {
  35.         x0 = (x1 + x2) / 2;
  36.         f0 = f(x0);
  37.  
  38.         cout << fixed << setprecision(9);
  39.         cout << setw(5) << i << "\t"
  40.              << setw(12) << x1 << "\t"
  41.              << setw(12) << x2 << "\t"
  42.              << setw(12) << x0 << "\t"
  43.              << setw(12) << f0 << "\t"
  44.              << setw(12) << f1 << "\t"
  45.              << setw(12) << f2 << endl;
  46.  
  47.         if (fabs(f0) < E) {
  48.             break;
  49.         }
  50.  
  51.         if (f1 * f0 < 0) {
  52.             x2 = x0;
  53.             f2 = f0;
  54.         } else {
  55.             x1 = x0;
  56.             f1 = f0;
  57.         }
  58.  
  59.         i++;
  60.     } while (fabs(x2 - x1) >= E);
  61.  
  62.     cout << "\nApproximate root = " << x0 << endl;
  63.     cout << "Total iterations = " << i << endl;
  64.  
  65.     return 0;
  66. }
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin 
Standard input is empty
stdout 
Enter the value of x0: Enter the value of x1: Enter the tolerance (E): Invalid interval! f(x0) and f(x1) must have opposite signs.
https://ideone.com/P6zwOw
language:
C++ 4.3.2 (gcc-4.3.2)
created:
12 days ago
visibility:
public

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