Re: NIntegrate and Plot
- To: mathgroup at smc.vnet.net
- Subject: [mg95801] Re: NIntegrate and Plot
- From: dh <dh at metrohm.com>
- Date: Wed, 28 Jan 2009 06:25:51 -0500 (EST)
- References: <glethi$4pp$1@smc.vnet.net> <glk80f$o7v$1@smc.vnet.net> <glmsrg$mjj$1@smc.vnet.net>
Hi Dimitris,
I must have fooled myself, I could actually integrate the function. I
think I got some typo in the input.
Daniel
dimitris wrote:
> On 26 =C9=E1=ED, 13:49, dh <d... at metrohm.com> wrote:
>> Hi Dimitris,
>>
>> integrate your function before plotting it:
>>
>> Integrate[fun[r, t], {t, 0, Infinity}, Assumptions -> {r >= 0}]
>>
>> hope this helps, Daniel
>>
>> dimitris wrote:
>>> Hello.
>>> I have the following function
>>> fun[r_, t_] := -(((-3 + 4*t^2 + 8*t^4 - 8*t^3*Sqrt[1 + t^2])*
>>> BesselJ[1, r*t])/(3 + 14*t^2 + 24*t^4 + 16*t^6 -
>>> 16*t^3*Sqrt[1 + t^2] - 16*t^5*Sqrt[1 + t^2]))
>>> How can I achieve better performance in the following task
>>> Plot[NIntegrate[fun[r, t], {t, 0, Infinity}], {r, 0, 3}]
>>> Thank you very much.
>
> Hi Daniel and thanks for your response.
> For what reason to use Integrate since Mathematica cannot evaluate
> analytically
> the integral?
>
> Dimitris
>