title: scipy.optimize.newton gives TypeError: 'float' object is not callable
body: <p>Im new to python and I was writing this simply code for finding the roots of the function:</p>
  
  <pre><code>from scipy import optimize
  
  x = eval(raw_input())                           #Initial guess
  f = eval(raw_input())                           # function to be evaluated
  F = eval(raw_input())                          #derivative of function f
  
  round(optimize.newton(f, x, F, tol = 1.0e-9), 4)
  </code></pre>
  
  <p>But the interpreter returns:
  TypeError: 'float' object is not callable</p>
  
  <p>I'm really not sure what im missing out from this code. Can someone help me out..thank you in advance</p>