Problem:
Compute the trace of
$\left(
\begin{array}{cc}
 0 & 2 \pi  \\
 2 \pi  & 2 \pi  \\
\end{array}
\right)$.
Answer:
$2 \pi$
{'source': 'AMPS', 'file': 'amps/mathematica/linear_algebra/trace/42012.txt'}