I have a system of two non-linear 2nd-order differential equations in terms of x(t), x'(t), x''(t), y(t), y'(t), t
The system is not very unstable, but near zero the values are out of the range of the machine. I thought it would'nt matter since I integrate from t = 66 to 72 with initial conditions at t = 66, but I get this message:
NDSolve::''ndnum'': ''Encountered non-numerical value for a derivative at
t == 2.524140890933554`*^-299.''
Does Mathematica always intergate from 0 even if the range asked for is far from 0? If so, how can I avoid that problem?
Since my solutions should all funnel to the same kind of behavior at very large t, it is clearly unstable to integrate with final conditions!