python - scipy.optimize.newton gives TypeError: 'float' object is not callable -

im new python , writing code finding roots of function:

from scipy import optimize  x = eval(raw_input())                           #initial guess f = eval(raw_input())                           # function evaluated f = eval(raw_input())                          #derivative of function f  round(optimize.newton(f, x, f, tol = 1.0e-9), 4) 

but interpreter returns: typeerror: 'float' object not callable

i'm not sure im missing out code. can me out..thank in advance

optimize.newton expects reference callable object (for example function). not mean give function string 'x*x' have define 1 first, like:

def my_func (x):     return x*x 

then can plug my_func optimize.newton (besides other required parameters).