  The Weyl quantization of classical observables on the torus (as phase space)
without regularity assumptions is explicitly computed. The equivalence class of
symbols yielding the same Weyl operator is characterized. The Heisenberg
equation for the dynamics of general quantum observables is written through the
Moyal brackets on the torus and the support of the Wigner transform is
characterized. Finally, a dequantization procedure is introduced that applies,
for instance, to the Pauli matrices. As a result we obtain the corresponding
classical symbols.
