[SciPy-user] bessel jn

[fred]

fred a écrit :
> Hi all,
> 
> I want to display cylindrical resonator eigenmodes using imv's mayavi &
> scipy bessel functions.
> (see attached file).
> 
> Almost works fine, I can display TE modes on Ex and Ey :
> ./foo 1 1 1 TE_Ex
> ./foo 1 1 1 TE_Ey
> 
> But I can't display module of E = sqrt(Ex*Ex + Ey*Ey) :
> ./foo 1 1 1 TE_Ev
Ok, seems that python does not handle correctly jn(r)/r for r = 0 (NaN)
whereas limit exists.
Two solutions :
1) if r = 0, I can set r=1e-5 and it works fine.
2) But I could also calculate limit of jn(r)/r in r = 0.
How can I do this ?
I read numpy doc and saw nothing.

Cheers,

-- 
Fred.