Re: Series of LaguerreL problem
- To: mathgroup at smc.vnet.net
- Subject: [mg72791] Re: [mg72785] Series of LaguerreL problem
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Sat, 20 Jan 2007 02:40:30 -0500 (EST)
- Reply-to: hanlonr at cox.net
These are the correct first few terms of the series expansion. The complete series is
Sum[(-1)^m*FunctionExpand[LaguerreL[n-m,m,0]]*z^m/m!,
{m,0,Infinity}]//FullSimplify
LaguerreL[n,z]
Bob Hanlon
---- Arturas Acus <acus at itpa.lt> wrote:
> Dear Group,
>
>
> Using 5.2 version and looking at the help browser on LaguerreL[]
> function I see the following line
>
> In[1]:=
> Series[LaguerreL[n, z], {z, 0, 4}]
>
> Out[1]:=
> SeriesData[z, 0, {LaguerreL[n, 0], -LaguerreL[-1 + n, 1, 0],
> LaguerreL[-2 + n, 2, 0]/2, -LaguerreL[-3 + n, 3, 0]/6, LaguerreL[-4 + n,
> 4, 0]/24}, 0, 5, 1]
>
> Does it have any sense? Certainly, I can call FunctionExpand[] on the
> Normal[%]
>
> The behaviour of version 5.0 was different and I suspect bug here.
>
> Explanation/motivation or bug confirmation would be wellcome.
>
>
> --
> Arturas Acus <acus at itpa.lt>