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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. double f(double co[], int n, double x)
  5. {
  6.     double result = co[0];
  7.     for (int i = 1; i <= n; i++)
  8.         result = result * x + co[i];
  9.     return result;
  10. }
  11.  
  12. double df(double co[], int n, double x)
  13. {
  14.     double result = co[0] * (n);
  15.     for (int i = 1; i < n; i++)
  16.         result = result * x + co[i] * (n - i);
  17.     return result;
  18. }
  19.  
  20. int main() {
  21.     int n;
  22.     double co[20];
  23.     double x0, x1, fx, dfx, E, error;
  24.     int iteration = 1, maxIter = 20;
  25.  
  26.     cout << "ENTER THE TOTAL NO. OF POWER::: ";
  27.     cin >> n;
  28.  
  29.     cout << endl;
  30.     for (int i = 0; i <= n; i++) {
  31.         cout << "x^" << i << " :: ";
  32.         cin >> co[i];
  33.     }
  34.  
  35.     cout << "\nTHE POLYNOMIAL IS ::: ";
  36.     for (int i = n; i >= 0; i--) {
  37.         cout << co[n - i] << "x^" << i << " ";
  38.     }
  39.     cout << endl;
  40.  
  41.     cout << "\nEnter initial guess x0: ";
  42.     cin >> x0;
  43.     cout << "Enter tolerance (e.g. 0.0001): ";
  44.     cin >> E;
  45.  
  46.     cout << "\n***********************************************";
  47.     cout << "\nIteration\t x\t\t f(x)\t\t f'(x)\t\t Error\t\t %Error";
  48.     cout << "\n***********************************************\n";
  49.  
  50.     do {
  51.         fx = f(co, n, x0);
  52.         dfx = df(co, n, x0);
  53.  
  54.         if (dfx == 0) {
  55.             cout << "Division by zero!.\n";
  56.             return 0;
  57.         }
  58.  
  59.         x1 = x0 - fx / dfx;
  60.         error = fabs((x1 - x0) / x1);
  61.  
  62.         cout << fixed << setprecision(6);
  63.         cout << setw(5) << iteration << "\t"
  64.              << setw(10) << x1 << "\t"
  65.              << setw(10) << fx << "\t"
  66.              << setw(10) << dfx << "\t"
  67.              << setw(10) << error << "\t"
  68.              << setw(10) << error * 100 << endl;
  69.  
  70.         if (error < E)
  71.             break;
  72.  
  73.         x0 = x1;
  74.         iteration++;
  75.  
  76.     } while (iteration <= maxIter);
  77.  
  78.     cout << "\n***********************************************";
  79.     cout << "\nTHE ROOT OF EQUATION IS " << x1 << endl;
  80.     cout << "***********************************************\n";
  81.  
  82.     return 0;
  83. }
  84.  
Success #stdin #stdout 0.01s 5284KB
comments (?)
stdin 
3
-3
-1
0
1
3
stdout 
ENTER THE TOTAL NO. OF POWER::: 
x^0 :: x^1 :: x^2 :: x^3 :: 
THE POLYNOMIAL IS ::: -3x^3 -1x^2 0x^1 1x^0 

Enter initial guess x0: Enter tolerance (e.g. 0.0001): 
***********************************************
Iteration	 x		 f(x)		 f'(x)		 Error		 %Error
***********************************************
    1	  1.977011	-89.000000	-87.000000	  0.517442	 51.744186
    2	  1.310268	-26.090464	-39.131193	  0.508860	 50.886028
    3	  0.897181	 -7.465217	-18.071759	  0.460428	 46.042844
    4	  0.679071	 -1.971444	 -9.038759	  0.321189	 32.118908
    5	  0.606350	 -0.400570	 -5.508373	  0.119931	 11.993108
    6	  0.598288	 -0.036454	 -4.521647	  0.013475	  1.347541
    7	  0.598194	 -0.000418	 -4.418115	  0.000158	  0.015821
    8	  0.598193	 -0.000000	 -4.416906	  0.000000	  0.000002
    9	  0.598193	 -0.000000	 -4.416906	  0.000000	  0.000000
   10	  0.598193	  0.000000	 -4.416906	  0.000000	  0.000000

***********************************************
THE ROOT OF EQUATION IS 0.598193
***********************************************
https://ideone.com/RSV5Lo
language:
C++ (gcc 8.3)
created:
11 days ago
visibility:
public

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