Python Newton Method

Implementation of Newton Method written in Python.

IN
-3
0.000001
OUT
X:  -3.0  f(x):  2.0
X:  -2.5  f(x):  0.25
X:  -2.4166666666666665  f(x):  0.006944444444443976
X:  -2.4142156862745097  f(x):  6.007304882427178e-06

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

def functionDerivative(x):
  return 2 * x + 2

intervalBegin = float(input("Enter inital guess: "))
precision = float(input("Enter precision of method: "))

x = intervalBegin
prevX = intervalBegin
while(abs(function(x)) > precision):
  print("X: ", x, " f(x): ", function(x))

  x = prevX - (function(prevX) / functionDerivative(prevX))
  prevX = x