[Numpy-discussion] no ordinary Bessel functions?

Anne Archibald peridot.faceted@gmail....
Tue Dec 15 09:32:55 CST 2009


2009/12/14 Dr. Phillip M. Feldman <pfeldman@verizon.net>:
>
> When I issue the command
>
> np.lookfor('bessel')
>
> I get the following:
>
> Search results for 'bessel'
> ---------------------------
> numpy.i0
>    Modified Bessel function of the first kind, order 0.
> numpy.kaiser
>    Return the Kaiser window.
> numpy.random.vonmises
>    Draw samples from a von Mises distribution.
>
> I assume that there is an ordinary (unmodified) Bessel function in NumPy,
> but have not been able to figure out how to access it. Also, I need to
> operate sometimes on scalars, and sometimes on arrays. For operations on
> scalars, are the NumPy Bessel functions significantly slower than the SciPy
> Bessel functions?

I am afraid this is one of the historical warts in numpy. The proper
place for special functions is in scipy.special, which does indeed
have various flavours of Bessel functions.

Anne


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