Re: Problem with evaluation of Besel Functions

*To*: mathgroup at smc.vnet.net*Subject*: [mg55992] Re: Problem with evaluation of Besel Functions*From*: Peter Pein <petsie at arcor.de>*Date*: Wed, 13 Apr 2005 01:10:19 -0400 (EDT)*References*: <d3g8kd$smh$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Ariel sumeruk wrote: > Hello > I am having a problem evaluating various functions, One example is the following > > BesselJ[1.5, 0] evaluates to 0 I guess Mathematica has this coded as special case (BesselJ[n_/;n!=0,0]:=0), as BesselJ[3/2,z] evaluates to (Sqrt[2/Pi]*(-Cos[z] + Sin[z]/z))/Sqrt[z]. And BesselJ[3/2,z]/.z->0 gives (of course) Indeterminate. > but > (BesselJ[xx, yyy] /. xx -> 1.5) /. yyy -> 0 evaluates to complex infinity > > I seem to encounter many of these problems with Bessel and Legendre > functions where I get actual diffrent numerical results depending on > How I set the parameters. > Thanks for anyone who might help > Ariel > -- Peter Pein Berlin