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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. pair<double,double> horner(const vector<double>& a, double x){
  5.     double n = a.size() - 1;
  6.     double p = a[0];
  7.     double dp = 0;
  8.     for(int i = 1; i <= n; i++){
  9.         dp = dp * x + p;
  10.         p = p * x + a[i];
  11.     }
  12.     return {p, dp};
  13. }
  14.  
  15. int main(){
  16.     int n;
  17.     cin >> n;
  18.     vector<double> a(n+1);
  19.     for(int i = 0; i <= n; i++) cin >> a[i];
  20.  
  21.     double x0;
  22.     cin >> x0;
  23.     double E = 1e-8;
  24.  
  25.     cout << fixed << setprecision(8);
  26.     cout << "Iter\t x\t\t f(x)\t\t f'(x)\t\t error\n";
  27.  
  28.     for(int i = 1; i <= 100; i++){
  29.         auto [fx, dfx] = horner(a, x0);
  30.         if(dfx == 0){
  31.             cout << "Derivative zero. Stopping iteration.\n";
  32.             break;
  33.         }
  34.         double x1 = x0 - fx / dfx;
  35.         cout << i << "\t" << x0 << "\t" << fx << "\t" << dfx << "\t" << fabs(x1 - x0) << "\n";
  36.         if(fabs(x1 - x0) < E) {
  37.             cout << "Root = " << x1 << "\n";
  38.             break;
  39.         }
  40.         x0 = x1;
  41.     }
  42. }
Success #stdin #stdout 0.01s 5316KB
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stdin
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stdout
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Iter	 x		 f(x)		 f'(x)		 error
Derivative zero. Stopping iteration.
https://ideone.com/5yM97i
language:
C++14 (clang 8.0)
created:
8 days ago
visibility:
public

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