Python Secant Method

Implementation of Secant Method written in Python.

IN
-3
-1
0.0000001
OUT
X:  -3.0  f(x):  2.0
X:  -2.0  f(x):  -1.0
X:  -3.0  f(x):  2.0
X:  -2.3333333333333335  f(x):  -0.22222222222222188
X:  -2.4  f(x):  -0.04000000000000026
X:  -2.4146341463414633  f(x):  0.0011897679952406204
X:  -2.41421143847487  f(x):  -6.007286838749515e-06

# ? 2018 TheFlyingKeyboard and released under MIT License
# theflyingkeyboard.net
def function(x):
    return x * (x + 2) - 1

xn1 = float(input("Enter begining of interval: "))
xn = float(input("Enter end of interval: "))
precision = float(input("Enter precision of method: "))

x = xn1

if(function(xn1) * function(xn) < 0):
  while(abs(function(x)) > precision):
    print("X: ", x, " f(x): ", function(x))

    x = xn - ((function(xn) * (xn - xn1)) / (function(xn) - function(xn1)))
    xn1 = xn
    xn = x