WikiMath

  def lagrange(f, a, b, epsilon):
      c=(a*f(b)-b*f(a))/(f(b)-f(a))
      if abs(f(a)*f(c)) < epsilon:
          return c
      elif f(a)*f(c) < 0:
          return lagrange(f, a, c, epsilon)
      else:
          return lagrange(f, c, b, epsilon)


  def f(x):
      return x**3-x-1


  lagrange(f, 0, 2, 0.01)
  Out: 1.32421875