tSLRVU - Online C++0x Compiler & Debugging Tool

#include <bits/stdc++.h>
using namespace std;


double computeFunction(double x) {
    return x * x * x - 4.0;
}

int main() {
    double a, b, c, f_a, f_b, f_c, tolerance = 0.0001, root;
    int iteration = 0;


    while (true) {
        cout << "Enter two initial guesses: ";
        cin >> a >> b;

        f_a = computeFunction(a);
        f_b = computeFunction(b);

        cout << "f(a) = " << f_a << ", f(b) = " << f_b << endl;

        if (f_a * f_b < 0) break;
        else cout << "Invalid interval. Try again.\n";
    }


    c = (a - f_a * (b - a)) / (f_b - f_a);
    f_c = computeFunction(c);

    if (f_c == 0.0) {
        cout << fixed << setprecision(8);
        cout << "Exact root found: " << c << endl;
        return 0;
    }


    cout << "Iter\tc\t\ta\t\tb\t\tf(c)\t\tf(a)\t\tf(b)\n";
    cout << iteration << "\t" << fixed << setprecision(8)
         << c << "\t" << a << "\t" << b << "\t"
         << f_c << "\t" << f_a << "\t" << f_b << endl;

    while (true) {
        c = (a - f_a * (b - a)) / (f_b - f_a);
        f_c = computeFunction(c);
        iteration++;

        cout << iteration << "\t" << fixed << setprecision(8)
             << c << "\t" << a << "\t" << b << "\t"
             << f_c << "\t" << f_a << "\t" << f_b << endl;

        if (fabs((b - a) / b) < tolerance || iteration > 8) {
            break;
        }

        if (f_a * f_c < 0) {
            b = c;
            f_b = f_c;
        } else {
            a = c;
            f_a = f_c;
        }

        root = c;
    }

    cout << fixed << setprecision(8);
    cout << "Approximate root = " << root << endl;
    return 0;
}