The left side is the derivative of :
So we can integrate both sides of
Then integrate again to solve for :
With the given initial conditions, we find
The second equation says is either 1 or -1, but in the latter case, we would get in the first equation, which is undefined over the real numbers, so .
So there are two candidate solutions,
However, the second equation doesn't satisfy the initial value of the derivative, since . So the solution is