From hell's heart I stab at theeSaturday, September 18 2004 at 05:49 Rant
If this looks familiar to you, you might be trapped in Fourier calculus hell. Just like me.
For the rest of you, the first above is the two-dimensional wave function expressed in polar coordinates, and you're supposed to figure out u(r, ?, t), which gives the rise of the wave at a particular location at a particular time. The rest is the first steps towards solving it.
And things will get even more fun before the end ...