Solution
= Solution
At the central <stationary point>, $u=v=0$, so $f=0$. At each of the other <stationary points>, $u^2+v^2=2$ and hence $f=uv/e$. Therefore
$$
\boxed{\begin{aligned}
f(1,-1)&=0,\\
f(2,0)=f(0,-2)&=e^{-1},\\
f(2,-2)=f(0,0)&=-e^{-1}.
\end{aligned}}
$$