Re: Simplifying Bessel Functions
- To: mathgroup at smc.vnet.net
- Subject: [mg92505] Re: Simplifying Bessel Functions
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Thu, 2 Oct 2008 04:34:36 -0400 (EDT)
- Organization: The Open University, Milton Keynes, UK
- References: <gbvlu6$bch$1@smc.vnet.net>
Aaron Fude wrote:
> What do I need to do to make mathematica recognize the following
> expression as zero:
>
> BesselJ[0, BesselJZero[0, n]]
You could add an up-value to BesselJZero. Below, we unprotect the
built-in symbol BesselJZero and add the new rule thanks to
*TagSetDelayed* (shortcut "/: :=", w/o the quotes).
In[1]:= BesselJ[0, BesselJZero[0, n]]
Unprotect[BesselJZero];
BesselJZero /: BesselJ[0, BesselJZero[0, n_]] := 0
Protect[BesselJZero];
BesselJ[0, BesselJZero[0, n]]
Out[1]= BesselJ[0, BesselJZero[0, n]]
Out[5]= 0
(Note that the above definition is very broad since it works for any n,
not just for positive integers.)
HTH,
-- Jean-Marc