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  1. /*
  2. Name:Tarequl Islam
  3. ID :230241031
  4. Assignment 1:problem 1
  5. */
  6.  
  7. #include <bits/stdc++.h>
  8. using namespace std;
  9.  
  10. // Modified function name
  11. double customFunc(double val) {
  12.     return (2.0 * val * val * val + 3.0 * val - 1.0);
  13. }
  14.  
  15. int main() {
  16.     double left, right, midpoint, f_left, f_right, f_mid, tolerance = 0.0001, root;
  17.     int iteration = 0;
  18.  
  19.     // Input loop instead of goto
  20.     while (true) {
  21.         cout << "Enter two initial guesses: ";
  22.         cin >> left >> right;
  23.  
  24.         f_left = customFunc(left);
  25.         f_right = customFunc(right);
  26.  
  27.         if (f_left * f_right < 0) {
  28.             break;
  29.         } else {
  30.             cout << "Invalid interval. Try again.\n";
  31.         }
  32.     }
  33.  
  34.     // First midpoint calculation
  35.     midpoint = (left + right) / 2.0;
  36.     f_mid = customFunc(midpoint);
  37.  
  38.     if (f_mid == 0) {
  39.         cout << fixed << setprecision(8);
  40.         cout << "Exact root found: " << midpoint << endl;
  41.         return 0;
  42.     }
  43.  
  44.     // Header for output
  45.     cout << "Iter\tMidpoint\tLeft\tRight\tf(Mid)\tf(Left)\tf(Right)\n";
  46.     cout << iteration << "\t" << fixed << setprecision(8) << midpoint << "\t" 
  47.          << left << "\t" << right << "\t" 
  48.          << f_mid << "\t" << f_left << "\t" << f_right << endl;
  49.  
  50.     while (true) {
  51.         midpoint = (left + right) / 2.0;
  52.         f_mid = customFunc(midpoint);
  53.         iteration++;
  54.  
  55.         cout << iteration << "\t" << fixed << setprecision(8) << midpoint << "\t" 
  56.              << left << "\t" << right << "\t" 
  57.              << f_mid << "\t" << f_left << "\t" << f_right << endl;
  58.  
  59.         if (fabs((right - left) / right) < tolerance || iteration > 8) {
  60.             break;
  61.         }
  62.  
  63.         if (f_left * f_mid < 0) {
  64.             right = midpoint;
  65.             f_right = f_mid;
  66.         } else {
  67.             left = midpoint;
  68.             f_left = f_mid;
  69.         }
  70.  
  71.         root = midpoint;
  72.     }
  73.  
  74.     cout << fixed << setprecision(8) << "Approximate root = " << root << endl;
  75.     return 0;
  76. }
Success #stdin #stdout 0s 5320KB
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stdout
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Enter two initial guesses: Iter	Midpoint	Left	Right	f(Mid)	f(Left)	f(Right)
0	1.00000000	-1.00000000	3.00000000	4.00000000	-6.00000000	62.00000000
1	1.00000000	-1.00000000	3.00000000	4.00000000	-6.00000000	62.00000000
2	0.00000000	-1.00000000	1.00000000	-1.00000000	-6.00000000	4.00000000
3	0.50000000	0.00000000	1.00000000	0.75000000	-1.00000000	4.00000000
4	0.25000000	0.00000000	0.50000000	-0.21875000	-1.00000000	0.75000000
5	0.37500000	0.25000000	0.50000000	0.23046875	-0.21875000	0.75000000
6	0.31250000	0.25000000	0.37500000	-0.00146484	-0.21875000	0.23046875
7	0.34375000	0.31250000	0.37500000	0.11248779	-0.00146484	0.23046875
8	0.32812500	0.31250000	0.34375000	0.05503082	-0.00146484	0.11248779
9	0.32031250	0.31250000	0.32812500	0.02666569	-0.00146484	0.05503082
Approximate root = 0.32812500
https://ideone.com/JsNjbW
language:
C++ (gcc 8.3)
created:
5 days ago
visibility:
public

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