bisection.py

def bisection(f, a, b, delta, max_steps):
    l = a
    r = b
    for _ in range(max_steps):
        p = (l + r) / 2
        print("[{:02d}] {} {} {}".format(_, l, p, r))
        s = f(p) * f(l)
        if s < 0:
            r = p
        elif s > 0:
            l = p
        else:
            return p
        if ((r - l) / 2) < delta:
            return p

def f(x):
    return x ** 2 - 2

print(bisection(f, 0, 2, 10 ** (-9), 100))