import math


def func(x):
    return x - 2 * math.exp(-x)


def derivative(x):
    return 1 + 2 * math.exp(-x)


def bisection(left, right, n):
    if n == 3:
        print(func((left + right) / 2))
        print((left + right) / 2)
        print()
        return (left + right) / 2
    middle = func((left + right) / 2)
    n += 1
    if middle * func(left) < 0:
        return bisection(left, (right + left) / 2, n)
    else:
        return bisection((left + right) / 2, right, n)


def steffensen(x0, n):
    g = lambda x : func(x + func(x)) / func(x)
    for i in range(n):
        x0 -= func(x0) / g(x0)
    print(func(x0))
    print(x0)


def newton(x0, n):
    for i in range(n):
        x0 -= func(x0) / derivative(x0)
    print(func(x0))
    print(x0)
    print()


bisection(0, 1, 1)
steffensen(0, 30)
newton(0, 3)