Hi, using Mathematica 8.0 I typed
Integrate[D[ArcTan[(x y)/Sqrt[x^2 + y^2 + 1]], y], y]
I get an ugly complex result which I tried to simplify in the original ArcTan form. I didn't succeded in doing this. I tried ExpToTrig, FullSimplify, and even to make Mathematica 8.0 calculate Re and Im part, with assumption Im[x]==0 and Im[y]==0.
The strange thing is that Matematica 5.2 immediatly gives the correct result. Is there any way to get the same result with Mathematica 8.0?