f(x,y)= \left\{ \begin{array}{rcl}
 
x^2+y^2 & \mbox{za} & x^2+y^2 \leq 4 \right \\
 
2(x^2+y^2) & \mbox{za} & x^2+y^2 > 4 \right \\ 
 
\end{array}\right