[SciPy-user] jn & lpmn or sph_jn...

[fred]

Hi,

I like how jn works because I can array as arg (I use jn on 3D array).

This is not the case for sph_jn & lpmn :-(

I tried to bypass it, with something like

def foo(m,n):
    x = arange(0,Lx,dx)
    y = arange(0,Ly,dy)
    z = arange(0,Lz,dz)
    tab = zeros((len(x), len(y), len(z)), dtype='f')
    for i in range(0,len(x)):
        for j in range(0,len(y)):
            for k in range(0,len(z)):
              tab[i,j,k] = cos(theta(x[i],y[j],z[k]))
#               tab[i,j,k] =
Ymn_theta_p(x[i],y[j],z[k],m,n)*sph_jn(n,r(x[i],y[j],z[k]))[n][0]*rho(x[i],y[j],z[k])
    return (tab)

but knowing my arrays have more than hundred of thousand cells, it is
_very_ slow.

I guess sph_jn  & lpmn are written like this because they return arrays
(0 to n order, derivative, etc).

I wish to have Legendre & spherical Bessel functions which could accept
array as arg.
I only need the last order (n) and the derivative (which could be called
by another func) for the same order.

How could I write this ?

Or is there another way to do the same thing ?

Ex. :

In [1]: from scipy.special import *

In [2]: x=arange(0,1,0.1)

In [3]: print jn(1,x)
[ 0.          0.04993753  0.09950083  0.14831882  0.19602658  0.24226846
  0.28670099  0.32899574  0.36884205  0.40594955]

In [4]: print sph_jn(1,x)
---------------------------------------------------------------------------
exceptions.ValueError                                Traceback (most
recent call last)

/home/fred/<ipython console>

/usr/local/lib/python2.4/site-packages/scipy/special/basic.py in
sph_jn(n, z)
    212     """
    213     if not (isscalar(n) and isscalar(z)):
--> 214         raise ValueError, "arguments must be scalars."
    215     if (n!= floor(n)) or (n<0):
    216         raise ValueError, "n must be a non-negative integer."

ValueError: arguments must be scalars.


Cheers,

-- 
Fred.