setting an array element with sequence problem problem

[Debashish Saha]

from __future__ import division
from numpy import*
import numpy as np
import matplotlib.pyplot as plt
from scipy.special import jv
from scipy.special import yn


h_cross=1
m=1
E=np.linspace(0.1,10,100)

V0=-100
R=2
K=(2*E)**0.5
K_P=(2*(E-V0))**0.5




'''r=np.linspace(-10,10,1000)
def V(r):
    if r>0 and r<R:
        return V0
    return 0
V=np.vectorize(V)
ax.set_ylim(-200,10)
plt.plot(r,V(r))'''


def sph_jv(l,r):
    return (pi/(2*r))**0.5*jv(l+0.5,r)



def sph_yn(l,r):
    return (pi/(2*r))**0.5*yn(l+0.5,r)




def delta_l(K,l):
    return arctan(((K_P*R)**2*sph_jv(l,K*R)-(2*l+3)*(K*R)*sph_jv(l+1,K*R))/((K_P*R)**2*sph_yn(l,K*R)-(2*l+3)*(K*R)*sph_yn(l+1,K*R)))
l=6
delta_l=np.vectorize(delta_l)
plt.plot(K,delta_l(l,K))

plt.show()





ValueError                                Traceback (most recent call last)
C:\Python27\lib\site-packages\IPython\utils\py3compat.pyc in
execfile(fname, glob, loc)
    166             else:
    167                 filename = fname
--> 168             exec compile(scripttext, filename, 'exec') in glob, loc
    169     else:
    170         def execfile(fname, *where):

C:\Users\Neeraj\Desktop\14.py in <module>()
     45 l=6
     46 delta_l=np.vectorize(delta_l)
---> 47 plt.plot(K,delta_l(l,K))
     48
     49 display(gcf())

C:\Python27\lib\site-packages\numpy\lib\function_base.pyc in
__call__(self, *args)
   1880         if self.nout == 1:
   1881             _res = array(self.ufunc(*newargs),copy=False,
-> 1882                          subok=True,dtype=self.otypes[0])
   1883         else:
   1884             _res = tuple([array(x,copy=False,subok=True,dtype=c) \

ValueError: setting an array element with a sequence.