Originally Posted by

**topsquark** Any unit vector parallel to the yz plane will take the form:

<0, cos(phi), sin(phi)>

So r(t) must be proportional to one of these in general.

Comparing the x components we see that

cos(t^2) = 0

Thus

t^2 = (2n + 1)pi/2 for n = 0, 1, 2, ...

t = (+/-)sqrt{(2n + 1)pi/2}

Additionally, dividing the z component by the y component gives us:

e^(sqrt(t))/t = tan(phi)

Since tan(phi) can be any angle t can be any value, so this doesn't give any restrictions on t. So the solution is:

t = (+/-)sqrt{(2n + 1)pi/2}

-Dan