Or, we could have Mathematica do all the nasty approximations behind our backs and use NDSolve:
This error message is a warning that you can't trust this approximation beyond about . To fix that, you must increase the maximum number of steps (which will take longer to compute):
Now, as before:
You had better pay attention to this warning. What is the problem? We told NDSolve to solve on the domain , not for negative t. This is something you need to watch out for.