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 >