NDSolve from negative to positive time

*To*: mathgroup at smc.vnet.net*Subject*: [mg89103] NDSolve from negative to positive time*From*: Allen Robnett <alrobnett at alumni.princeton.edu>*Date*: Mon, 26 May 2008 01:27:52 -0400 (EDT)

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