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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. double f(double co[], int n, double x) {
  5.     double result = co[0];
  6.     for (int i = 1; i <= n; i++)
  7.         result = result * x + co[i];
  8.     return result;
  9. }
  10.  
  11. double df(double co[], int n, double x) {
  12.     double result = co[0] * n;
  13.     for (int i = 1; i < n; i++)
  14.         result = result * x + co[i] * (n - i);
  15.     return result;
  16. }
  17.  
  18. int main() {
  19.     int n;
  20.     double co[20];
  21.     double x0, x1, fx, dfx, E, error;
  22.     int iteration = 1, maxIter = 20;
  23.  
  24.     cout << "ENTER THE TOTAL NO. OF POWER::: ";
  25.     cin >> n;
  26.  
  27.     for (int i = 0; i <= n; i++) {
  28.         cout << "x^" << i << " :: ";
  29.         cin >> co[i];
  30.     }
  31.  
  32.     cout << "\nTHE POLYNOMIAL IS ::: ";
  33.     for (int i = n; i >= 0; i--) {
  34.         cout << co[n - i] << "x^" << i << " ";
  35.     }
  36.     cout << endl;
  37.  
  38.     cout << "\nEnter initial guess x0: ";
  39.     cin >> x0;
  40.     cout << "Enter tolerance (e.g. 0.0001): ";
  41.     cin >> E;
  42.  
  43.     cout << "\n***********************************************";
  44.     cout << "\nIteration\t x\t\t f(x)\t\t f'(x)\t\t Error\t\t %Error";
  45.     cout << "\n***********************************************\n";
  46.  
  47.     while (iteration <= maxIter) {
  48.         fx = f(co, n, x0);
  49.         dfx = df(co, n, x0);
  50.  
  51.         if (dfx == 0) {
  52.             cout << "Division by zero!.\n";
  53.             return 0;
  54.         }
  55.  
  56.         x1 = x0 - fx / dfx;
  57.         error = fabs((x1 - x0) / x1);
  58.  
  59.         cout << fixed << setprecision(6);
  60.         cout << setw(5) << iteration << "\t"
  61.              << setw(10) << x1 << "\t"
  62.              << setw(10) << fx << "\t"
  63.              << setw(10) << dfx << "\t"
  64.              << setw(10) << error << "\t"
  65.              << setw(10) << error * 100 << endl;
  66.  
  67.         if (error < E)
  68.             break;
  69.  
  70.         x0 = x1;
  71.         iteration++;
  72.     }
  73.  
  74.     cout << "\n***********************************************";
  75.     cout << "\nTHE ROOT OF EQUATION IS " << x1 << endl;
  76.     cout << "***********************************************\n";
  77.  
  78.     return 0;
  79. }
Success #stdin #stdout 0s 5324KB
comments (?)
stdin 
3
-6
11
-6
1
3.5
0.0001
stdout 
ENTER THE TOTAL NO. OF POWER::: x^0 :: x^1 :: x^2 :: x^3 :: 
THE POLYNOMIAL IS ::: -6x^3 11x^2 -6x^1 1x^0 

Enter initial guess x0: Enter tolerance (e.g. 0.0001): 
***********************************************
Iteration	 x		 f(x)		 f'(x)		 Error		 %Error
***********************************************
    1	  2.546823	-142.500000	-149.500000	  0.374261	 37.426133
    2	  1.916633	-42.048401	-66.723409	  0.328800	 32.880035
    3	  1.504846	-12.335800	-29.956756	  0.273641	 27.364054
    4	  1.243721	 -3.565800	-13.655501	  0.209955	 20.995514
    5	  1.090958	 -0.990101	 -6.481285	  0.140027	 14.002664
    6	  1.019561	 -0.244343	 -3.422324	  0.070027	  7.002704
    7	  1.001214	 -0.041845	 -2.280737	  0.018325	  1.832476
    8	  1.000005	 -0.002438	 -2.017019	  0.001209	  0.120858
    9	  1.000000	 -0.000010	 -2.000072	  0.000005	  0.000512

***********************************************
THE ROOT OF EQUATION IS 1.000000
***********************************************
https://ideone.com/7PpBI3
language:
C++14 (clang 8.0)
created:
13 days ago
visibility:
public

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