import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
from numpy.polynomial import Polynomial

f = Polynomial([2.0, 1.0, -6.0, -2.0, 2.5, 1.0])
a = -0.5
b = 1.3
m = (a+b)/2
e = 1e-6

list_a = []
list_b = []
list_m = []
list_f = []

root = 0.0

#+----------------------+
#| Start of your code   +
#+----------------------+
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
from numpy.polynomial import Polynomial

f = Polynomial([2.0, 1.0, -6.0, -2.0, 2.5, 1.0])
a = -0.5
b = 1.3
m = (a+b)/2
e = 1e-6

list_a = []
list_b = []
list_m = []
list_f = []

root = 0.0

#+----------------------+
#| Start of your code   +
#+----------------------+
while True:
    list_a.append(a)
    list_b.append(b)
    list_m.append(m)
    list_f.append(f(m))


    if(f(a)*f(m)<0):
        b=m
        m=(a+b)/2
        list_a.append(a)
        list_m.append(m)
        list_b.append(b)

        list_f.append(f(m))
    else:
        a=m
        m=(a+b)/2

        list_a.append(a)
        list_b.append(b)
        list_m.append(m)
        list_f.append(f(a))


    if(abs(list_m[-1]-list_m[-2])/abs(list_m[-1])<=e):
        root=m
        break






#+--------------------+
#| End of your code   +
#+--------------------+

xs = np.linspace(-2.5, 1.6, 100)
ys = f(xs)

plt.axhline(y=0, color='k')
plt.plot(xs, ys)
plt.plot(root, f(root), 'ro')

print(pd.DataFrame({'a':list_a, 'b':list_b, 'm':list_m, 'f(x)':list_f}))