setting an array element with sequence problem problem

[Robert Kern]

On 4/27/12 7:18 PM, Debashish Saha wrote:

You will want to ask numpy questions on the numpy mailing list.

   http://www.scipy.org/Mailing_Lists

When you do, I recommend stating a clear question in addition to the code and 
the traceback (although those are very much appreciated). But just to get you on 
your way, remove the np.vectorize() line (you don't need it) and double-check 
the order of arguments that you are passing to delta_l(K,l).

> 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.


-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco