Re: numerical integration

*To*: mathgroup at smc.vnet.net*Subject*: [mg69333] Re: numerical integration*From*: p-valko at tamu.edu*Date*: Thu, 7 Sep 2006 04:30:35 -0400 (EDT)*References*: <edm1d1$coc$1@smc.vnet.net>

You just have to multiply the Bessel function by something. The simplest is to put there 1. NIntegrate[BesselJ[0, x] 1., {x, 0, Infinity}, Method -> Oscillatory] The result will be: 1. dimmechan at yahoo.com wrote: > Hi. > > I posted a similar message before one month but since there was not a > reply I repost just the basic questions again. > > 1) Why > > NIntegrate[BesselJ[0,x],{x,0,Infinity},Method->Oscillatory] > > does not work, while e.g. > > NIntegrate[BesselJ[0,x]BesselJ[1,x],{x,0,Infinity},Method->Oscillatory] > > > works fine? > > 2) Why > > Integrate[BesselJ[n,x],{x,0,Infinity}] > > gives the following conditional result > > If[Re[n] > -1, 1, Integrate[BesselJ[n, x], {x, 0, Infinity}, > Assumptions -> Re[n] <= -1]] > > while > > Integrate[{BesselJ[ - 5,x],BesselJ[ - 8,x]},{x,0,Infinity}] > > Integrate::gener: Unable to check convergence. More... > > Integrate::gener: Unable to check convergence. More... > > {-1, -1} > > 3) Why exist the warning messages regarding convergence in the previous > command as also > in the following command? > > Integrate[BesselJ[0,x],{x,0,Infinity}] > > Integrate::gener: Unable to check convergence. More... > > 1 > > Cheers, > > Dimitrios Anagnostou