Numerical Analysis

def bisect(f,a,b,TOL=0.000004):
    u_a = a
    u_b = b
    while(u_b-u_a)/2.0 > TOL:
        c = (u_a+u_b)/2.0
        if f(c) == 0:
            break
        if f(u_a)*f(c) < 0:
            u_b = c
        else:
            u_a = c

    u_c = (u_a + u_b) / 2.0
    return u_c

f = lambda x: x*x*x + x - 1
ret = bisect(f,-1.0,1.0)
print(ret)

print(f(ret))