python - TypeError: 'Quantity' object is not callable -

i attempting understand quantity error.
using python version 2.7.1 , numpy quantities package. have posted defined variables , equations , subsequent error. attempting generate array values of teffpv vary theta (th). can explain why creating error?

a = q.quantity(0.2,'au').simplified e = 0.2 r = q.quantity(0.4,'rsun').simplified # radius of blackbody t = q.quantity(3500,'k').simplified #temperature teff of star al = 0.3 n = 100 th = np.linspace(0.,4*np.pi,n) def d(a,e,th):     return a*(1-e**2)/(1+e*np.cos(th)) def teffp(al,t,r,d):     return ((1.- al)**(1/4))*t*(r/d(a,e,th))**(1/2) teffpv = np.zeros(n) # make arrays store results in range(n-1):     teffpv=teffp(al,t,r,d(a,e,th[i])) 

error message

typeerror                                 traceback (most recent call last) <ipython-input-17-bdcc9550c9ae> in <module>()      14 teffpv = np.zeros(n) # make arrays store results      15 in range (n-1): ---> 16     teffpv=teffp(al,t,r,d(a,e,th[i]))  <ipython-input-17-bdcc9550c9ae> in teffp(al, t, r, d)      11     return a*(1-e**2)/(1+e*np.cos(th))      12 def teffp(al,t,r,d): ---> 13     return ((1.- al)**(1/4))*t*(r/d(a,e,th))**(1/2)      14 teffpv = np.zeros(n) # make arrays store results      15 in range (n-1):  typeerror: 'quantity' object not callable 

your code has mistakes :

• no need initialize teffpv np.zeros(n) , use loop.
• replace d(a,e,th) d in formula of teffp -> explains error message
• use float rational exponents, in teffp function

this code should want :

import quantities q import numpy np  = q.quantity(0.2,'au').simplified e = 0.2 rsun = q.unitquantity('solar radius', q.m*6.9599e8, symbol='rsun') r = q.quantity(0.4,'rsun').simplified # radius of blackbody t = q.quantity(3500.,'k').simplified #temperature teff of star al = 0.3 n = 100 th = np.linspace(0.,4.*np.pi,n)  def d(a,e,th):   return a*(1-e**2)/(1+e*np.cos(th))  def teffp(al,t,r,d):   return ((1.- al)**(0.25))*t*(r/d)**(0.5)  teffpv = teffp(al,t,r,d(a,e,th)) print teffpv 

nb:

i added definition of rsun unit in code otherwise quantities package doesn't recognize it.

i'm not astrophysicist found here ;)