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Re: DSolve Issues

  • To: mathgroup at smc.vnet.net
  • Subject: [mg88381] Re: DSolve Issues
  • From: donkorgi12 <ringtailinblacklw02 at gmail.com>
  • Date: Sat, 3 May 2008 06:18:18 -0400 (EDT)
  • References: <fveguc$5ed$1@smc.vnet.net>

On May 2, 2:47 am, donkorgi12 <ringtailinblackl... at gmail.com> wrote:
> I am solving the following Differential Equation
>
> Phi''[r]+2*r^(-1)Phi'[r]+0.104479*Phi[r]==0 and Phi[0]==K (some
> constant)   ; kinda has a cos/sin solution
>
> 2.71828^(-0.323232 \[ImaginaryI] r) ((0.+
>      0. \[ImaginaryI]) + (0.+ 0. \[ImaginaryI]) 2.71828^(
>     0.646465 \[ImaginaryI] r) + (0.+ 1.54687 \[ImaginaryI]) K - (0.+
>       1.54687 \[ImaginaryI]) 2.71828^(0.646465 \[ImaginaryI] r) K)
>
> all divided by r.
>
> My problem is that Mathematica is not treating those "zeros".... as
> well zeros. Thus, the solution cannot really be used. In fact, if I
> manually reproduce the solution and remove those "zeros", then the
> solution is fine.
>
> I have another similar ODE Anyone have any ideas.
>
> Phi''[r]+2*r^(-1)Phi'[r]- 287.31*Phi[r]==0 and Phi[3R]==0(some
> constant)  ; kinda has a cosh/sinh solution
>
> As you might have notice I need to match these two solutions and their
> derivatives at some point.  The ratio of which gives me what I desire
> the value of R.
>
> Yet, Mathematica treats those "zeros" as something else.

I just wanted to add the latter ODE works out find and that "I have
another similar ODE Anyone have any ideas" Should be

"Anyone have any ideas??

I have another similar ODE below that works fine"


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