I've used Mma on a very elementary basis for years, but often when I try to do the least thing beyond what I'm familiar with, it hangs or gets confused, etc. Case in point: Let f(u,v) = sqrt(5+4cos(u)) + 2.5*sin((u-v)/2) + sqrt(11-6cos(v)-2sin(v)). I wanted it to find the critical points, so I tried: Solve[{D[f[u,v],u] == 0, D[f[u,v],v] == 0}, {u,v}] and it seemed to have no idea what I was talking about. So I figured the partials by hand and confirmed them with Mma, and just used them directly instead of Df[u,v],u], etc. This time Mma canceled the calculation after 10-20 minutes, saying its memory had been used up. (Now I'm trying to get it to at least NSolve for the critical points.) But is there any way to get the original symbolic equation to come up with something useful, or does this just indicate the limits of symbolic computation? Thanks, Dan Sometimes the brain has a mind of its own.