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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. // f(x) = 3x - cos(x) - 1
  4. double f(double x) {
  5.     return 3*x - cos(x) - 1;
  6. }
  7.  
  8. signed main() {
  9.     ios_base::sync_with_stdio(false);  cin.tie(NULL);
  10.     int iter = 0;
  11.     double tol = 0.0001;
  12.     cout << "Iter\t" << "Root\n"; 
  13.  
  14.     // Root lies between [0..1]
  15.     double a = 0, b = 1;
  16.     double c, prev = 0;
  17.     do {
  18.         c = (a * f(b) - b * f(a)) / (f(b) - f(a));
  19.         cout << ++iter << "\t" << c << endl;
  20.         if (fabs(f(c)) < tol) {
  21.             break;
  22.         }
  23.  
  24.         if (f(c) * f(a) < 0) {
  25.             b = c;
  26.         } else {
  27.             a = c;
  28.         }
  29.         if (fabs(c - prev) < tol) {
  30.             break;
  31.         }
  32.  
  33.         prev = c;
  34.  
  35.     } while (fabs(b - a) > tol);
  36.  
  37. }
Success #stdin #stdout 0.01s 5288KB
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stdin
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Standard input is empty
stdout
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Iter	Root
1	0.578085
2	0.605959
3	0.607057
4	0.6071
https://ideone.com/3hRlx8
Regula Falsi
language:
C++14 (gcc 8.3)
created:
4 days ago
visibility:
public

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