Astigmatic hermite-gaussian function

gboff21

I have a formula for u_n(x,z) and u_m(y,z) where z is the direction of propagation and (x,y) is the transverse plane. To get a complete (x,y,z) function of u_nm(x,y,z) all you have to do is multiply them together right?
But when I do this in Matlab, I get something different (see attachment).
Any ideas?

Attached Images

supposed hermite-gaussian.bmp (161.8 KB, 5 views)