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  1. #include <cmath>
  2. #include <iostream>
  3.  
  4. using namespace std;
  5.  
  6. double functionA(double x) {
  7.     return sin(2.0 * x) - 1.0 + x;
  8. }
  9.  
  10. double functionB(double x) {
  11.     return 2.0 * x / (1.0 + x / 1.5);
  12. }
  13.  
  14. double bisectionMethod(double (*function)(double), double a, double b, double tolerance) {
  15.     double x;
  16.     double f;
  17.     double error = tolerance + 1;
  18.     int step = 0;
  19.     double fa = (*function)(a);
  20.     double fb = (*function)(b);
  21.     //Check the conditions of a root in the given interval
  22.     if (a < b) {
  23.         if (fa * fb < 0) {
  24.             while (error > tolerance) {
  25.                 step++;
  26.  
  27.                 x = (a + b) / 2.0;
  28.                 f = (*function)(x);
  29.  
  30.                 if (f == 0) {
  31.                     cout << "Root found in x = " << x;
  32.                     return x;
  33.                 } else if (f * fa > 0) {
  34.                     a = x;
  35.                 } else if (f * fa < 0) {
  36.                     b = x;
  37.                 }
  38.                 error = (b - a) / pow(2.0, (double) step + 1);
  39.             }
  40.             cout << "Root found in x = " << x;
  41.             return x;
  42.         } else {
  43.             cout << "There not exist a root in that interval." << endl;
  44.             return -1;
  45.         }
  46.     } else {
  47.         cout << "Mandatory \"a < b\", verify." << endl;
  48.         return -1;
  49.     }
  50. }
  51.  
  52. int main(int argc, char *argv[]){
  53.     bisectionMethod(functionA, -3.0, 3.0, 10.0e-7);
  54. }
Success #stdin #stdout 0.02s 2680KB
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Standard input is empty
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Root found in x = 0.354492
https://ideone.com/RsTT1
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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