       Re: NDSolve from negative to positive time

• To: mathgroup at smc.vnet.net
• Subject: [mg89142] Re: NDSolve from negative to positive time
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Tue, 27 May 2008 07:13:09 -0400 (EDT)
• Organization: Uni Leipzig
• References: <g1dhsu\$9l7\$1@smc.vnet.net>
• Reply-to: kuska at informatik.uni-leipzig.de

```Hi,

and just say that instead of

sol = NDSolve[{x''[t] + \[Gamma]*x'[t] + x[t] == Cos[t], x == 1,
x' == 0} /. \[Gamma] -> 0.05, x[t], {t, 0, 8 Pi}]

you wish to solve

sol = NDSolve[{x''[t] + \[Gamma]*x'[t] + x[t] == Cos[t], x == 1,
x' == 0} /. \[Gamma] -> 0.05, x[t], {t, -8 Pi, 8 Pi}]

does not help ??

Regards
Jens

Allen Robnett wrote:
> The answer to my question may be trivial, but I have not found it. I am dealing with the orbits in a three-body problem. I have written equations which do a beautiful job of 3D plotting the results from t=0 to any positive time. The only boundary conditions available are at t=0. I am able to get the correct 3D plot for negative time if I reverse all of the velocities at t=0. I assume that I can then get a plot that combines the two into one plot from negative time to positive time. But this seems very "klutsy" and I believe that Mathematica must provide a sophisticated way to get the   results in a single operation. Any suggestions?
>
> Allen Robnett
>

```

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