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"