Sofa

#include <iostream>
#include <math.h>

using namespace std;

double f(double x) {
    return 0.5 * x * x - sin(x);
}

void Sven(double x0, double h, double &a, double &b) {
    int k = 1;
    double x1, x2;
    if (f(x0 - h) >= f(x0) && f(x0) >= f(x0 + h)) {
        x1 = x0 + h;
    }
    else if (f(x0 - h) <= f(x0) && f(x0) <= f(x0 + h)) {
        x1 = x0 - h;
        h = -h;
    }
    if (!(f(x0 - h) >= f(x0) && f(x0) <= f(x0 + h))) {
        x2 = x1;
        x1 = x0;
        do {
            x0 = x1;
            x1 = x2;
            x2 = x1 + pow(2.0, 1.0 * k) * h;
        } while (f(x2) <= f(x1));
        if (h > 0) {
            a = x0;
            b = x2;
        }
        else {
            a = x2;
            b = x0;
        }
    }
    else {
        a = x0 - h;
        b = x0 + h;
    }
}

double trihotomia(double a, double b, double eps) {
    double m1, m2;
    while (b - a > eps) {
        m1 = a + (b - a) / 3;
        m2 = b - (b - a) / 3;
        if (f(m1) > f(m2))
            a = m1;
        else if (f(m1) < f(m2))
            b = m2;
        else {
            a = m1;
            b = m2;
        }
    }
    return a;
}

int main(void) {
    double a, b;
    double n, h, eps;
    cout << "Input x0: ";
    cin >> n;
    cout << "Input h: ";
    cin >> h;
    cout << "Input eps: ";
    cin >> eps;
    Sven(n, h, a, b);
    double result = trihotomia(a, b, eps);
    cout << a << " " << b << endl;
    cout << result << endl;
    return 0;
}