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  1. import java.util.Scanner;
  2.  
  3. class SecantHorner {
  4.                                                     //id=240242058 "(sakib)"
  5.     static double f(double[] coeffs, double x) {
  6.         double result = coeffs[0];
  7.         for (int i = 1; i < coeffs.length; i++) {
  8.             result = result * x + coeffs[i];
  9.         }
  10.         return result;
  11.     }
  12.  
  13.     public static void main(String[] args) {
  14.         Scanner sc = new Scanner(System.in);
  15.  
  16.         double[] coeffs = {1, 0, 0, -4}; // f(x) = x^3 - 4
  17.  
  18.         System.out.print("Enter first initial guess x1: ");
  19.         double x1 = sc.nextDouble();
  20.         System.out.print("Enter second initial guess x2: ");
  21.         double x2 = sc.nextDouble();
  22.         System.out.print("Enter tolerance: ");
  23.         double tol = sc.nextDouble();
  24.  
  25.         double f1 = f(coeffs, x1);
  26.         double f2 = f(coeffs, x2);
  27.         double x3 = 0, prev = x2, error;
  28.         int i = 0;
  29.  
  30.         System.out.printf("%-5s %-12s %-12s %-12s %-12s\n", "Iter", "x3", "f(x3)", "Error", "%Error");
  31.  
  32.         while (true) {
  33.             x3 = (f2*x1 - f1*x2) / (f2 - f1);
  34.             double f3 = f(coeffs, x3);
  35.             i++;
  36.  
  37.             error = Math.abs(x3 - prev);
  38.             double perError = (x3 != 0) ? (error / Math.abs(x3)) * 100 : 0;
  39.  
  40.             System.out.printf("%-5d %-12.8f %-12.8f %-12.8f %-12.8f\n", i, x3, f3, error, perError);
  41.  
  42.             if (Math.abs(f3) < tol) break;
  43.  
  44.             x1 = x2; f1 = f2;
  45.             x2 = x3; f2 = f3;
  46.             prev = x3;
  47.         }
  48.  
  49.         System.out.println("\nApproximate root = " + x3);
  50.         System.out.println("Total iterations = " + i);
  51.     }
  52. }
  53.  
Success #stdin #stdout 0.22s 61320KB
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stdin
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1
3
1e-8
stdout
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Enter first initial guess x1: Enter second initial guess x2: Enter tolerance: Iter  x3           f(x3)        Error        %Error      
1     1.23076923   -2.13563951  1.76923077   143.75000000
2     1.38109121   -1.36568876  0.15032198   10.88429062 
3     1.64772260   0.47355002   0.26663139   16.18181302 
4     1.57907284   -0.06262759  0.06864976   4.34747263  
5     1.58709140   -0.00234039  0.00801855   0.50523580  
6     1.58740268   0.00001233   0.00031129   0.01960975  
7     1.58740105   -0.00000000  0.00000163   0.00010273  

Approximate root = 1.5874010516500963
Total iterations = 7
https://ideone.com/joCGjt
language:
Java (HotSpot 12)
created:
1 day ago
visibility:
public

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