CPP/root.cpp at main · Pansarekomal039/CPP · GitHub

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#include "root.hpp"

using namespace std;

Root::Root() {}
double Root::f(double x) {
    return x* x  + 3 * x - 5;
}


double Root::f_derivative(double x) {
    return x* x  + 3 * x - 5;
}

double Root::g(double x) {
    return x* x  + 3 * x - 5;
}

void Root::bisection(double a, double b) {
    double x, fx, fa, fb;
    cout << fixed << setprecision(5);

    cout << "Enter the value of a: ";
    cin >> a;
    cout << "Enter the value of b: ";
    cin >> b;

    cout << "\nIteration\t  a\t\t b\t\t f(a)\t\t f(b)\t\t x\t\t f(x)" << endl;
    int iteration = 1;
    fa = f(a);
    fb = f(b);

    do {
        x = (a + b) / 2;
        fx = f(x);
        cout << iteration << "\t\t" << a << "\t" << b << "\t" << fa << "\t" << fb << "\t\t" << x << "\t" << fx << endl;

        if (fx < 0) {
            a = x;
            fa = fx;
        } else {
            b = x;
            fb = fx;
        }
        iteration++;

    } while (fabs(b - a) > 0.00001);

    cout << "The root is " << x << endl;
}

void Root::newtonRaphson(double x0) {
    double x, fx, fdx, x_next;
    const double tolerance = 0.00001;
    int iteration = 1;

    cout << "Enter the initial guess: ";
    cin >> x0;
    x = x0;

    cout << fixed << setprecision(5);
    cout << "\nIteration\t  x\t\t  f(x)\t\t  f'(x)" << endl;

    do {
        fx = f(x);
        fdx = f_derivative(x);

        if (fdx == 0) {
            cout << "Error: Derivative is zero" << endl;
            return;
        }

        x_next = x - (fx / fdx);

        cout << iteration << "\t\t" << x << "\t" << fx << "\t" << fdx << endl;

        if (fabs(x_next - x) < tolerance)
            break;

        x = x_next;
        iteration++;

    } while (true);

    cout << "\nApproximate Root from Newton-Raphson: " << x << endl;
}

void Root::FixedPoint(double x0) {
    const double tolerance = 0.00001;
    int maxIterations = 100;
    int iteration = 1;
    double x = x0, x_next;

    cout << "Enter the initial guess: ";
    cin >> x0;
    x = x0;

    cout << fixed << setprecision(5);
    cout << "\nIteration\t  x\t\t  g(x)\n";

    do {
        x_next = g(x);

        cout << iteration << "\t\t" << x << "\t" << x_next << endl;

        if (fabs(x_next - x) < tolerance)
            break;

        x = x_next;
        iteration++;

    } while (iteration <= maxIterations);

    cout << "\nApproximate Root from Fixed-Point Iteration: " << x << endl;
}