Re: Strange error message from NIntegrate
- To: mathgroup at smc.vnet.net
- Subject: [mg28152] Re: Strange error message from NIntegrate
- From: "Urijah Kaplan" <uak at sas.upenn.edu>
- Date: Mon, 2 Apr 2001 02:18:23 -0400 (EDT)
- Organization: University of Pennsylvania
- References: <9a6e2c$ep2@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
What are those brackets around 3/2 for?
--Urijah
"Henrik Holm" <h.holm at spray.no> wrote in message
news:9a6e2c$ep2 at smc.vnet.net...
> I am trying to do the following numerical integration:
>
> NIntegrate[x^{3/2}*Exp[-x]*BesselI[3/2,x/2], {x,0, Infinity}]
>
> this results in the following error,
>
> NIntegrate::"inum":
> Integrand {0.141859424324175} is not numerical at {x} = {1.}.
>
> I think this is very strange, after all, 0.1418... _is_ a
> number. It might be noted that doing the integration
> symbolically works nicely:
>
> Integrate[x^{3/2}*Exp[-x]*BesselI[3/2,x/2], {x,0, Infinity}]
>
> which gives the following result:
>
> 16/(9*Sqrt[pi])
>
>
> I guess I am doing something wrong, but I cannot understand
> what. Can anybody help me?
>
>
>
> Regards,
> Henrik Holm
>