[SciPy-dev] some interesting routines in Python SOMNEC program

eric eric at scipy.org
Wed Feb 13 14:26:24 CST 2002


> Actually, they are exposed.  Are they not working on your platform?

Hmmm. Yes.  Now I see that they are.  I had done a grep for zbesh, and it didn't
show up in the methods table, so I assumed none of them were there.  Now I see
the cbesh entries.  Should we add the double complex versions?

> The derivatives of any bessel function satisfy the recurrence relation:
>
> d C_v(z)
> ------- =  ( C_(v-1) (z) - C_(v+1) (z) ) / 2
>   dz
>
>           = C_(v-1) (z) - v / z * C_v(z)
>
>           = -C_(v+1) (z) + v / z * C_v(z)
>
>
> where C is any of the bessel functions or modified bessel functions or any
> linear combination of them.
>
> (From Abramowitz and Stegun pg. 361)

You had to look it up in a book? <wink>

> We could easily implement these derivatives if it is desired.

It might be.  we discuss this when we have a discussion about renaming the
functions in special...

see ya,
eric






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