Calculate potential of electrical dipole

DipolePotential.py

import numpy as np 

print "Calculate n terms of dipolar potential: "
n = int(raw_input("How many terms? "))
q = float(raw_input("What's the charges(C)? "))
l = float(raw_input("What's the distance between the charges(m)? "))
r = float(raw_input("What's the distance to the dipole(m)? "))
#theta = float(raw_input("What's the angle to the dipole in radians? "))

f0 = []
i = 1.0
j = -1
w = 0.0
e0 = 8.854187817
f0.append(i)

for x in range(n):
    i = np.divide(float(i*j),2)
    j -= 2
    #print j
    f0.append(i)
# print f0
angles = [0,(np.pi/2),(np.pi),(3*np.pi/2),(2*np.pi)]

for theta in angles:
    x = (-2*r*l*np.cos(theta))/(r*r)
    w = 0.0
    
    for i in range(n):
        w+= x * f0[i]/np.math.factorial(i)
    w = w*(q/(4*np.pi*e0/1000000000000))
    print "U(r) = ",w," for angle ", theta