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Re: Linear combination of Bessel functions

• To: mathgroup at smc.vnet.net
• Subject: [mg121400] Re: Linear combination of Bessel functions
• From: Leonid Shifrin <lshifr at gmail.com>
• Date: Wed, 14 Sep 2011 05:12:30 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <201109131122.HAA05158@smc.vnet.net>

Here is one way:

getBesselCoeff[n_, expr_] :=
  Module[{x},
   SeriesCoefficient[(expr /. BesselJ[n, _] :> (1/x))*x, {x, 0, 0}]];

So that

In[1503]:=
expr = r^2+Cos[r] BesselJ[0,rho r]+3 Sin[r] BesselJ[1,rho
r]+Log[r]BesselJ[2,rho r];
getBesselCoeff[#,expr]&/@{0,1,2}

Out[1504]= {Cos[r],3 Sin[r],Log[r]}

Regards,
Leonid


On Tue, Sep 13, 2011 at 3:22 PM, Sam Takoy <sam.takoy at yahoo.com> wrote:

> Hi,
>
> Suppose I have an expression that's a linear combination of Bessel
> function. Kind of like this
>
> r^2 + Cos[r] BesselJ[0, rho r] + 3 Sin[r] BesselJ[1, rho r] + Log[r]
> BesselJ[2, rho r]
>
> Is there a way to extract the coefficients of the linear combination?
>
> Thanks,
>
> Sam
>
>

• References:
  • Linear combination of Bessel functions
    • From: Sam Takoy <sam.takoy@yahoo.com>