Formula_20038

\[\begin{gathered}f(x, y) \rightarrow A_{f}=(2 \pi)^{-n} \int \ldots \int f(x, y) \times \\\times \exp \left[-i \sum_{j=1}^{n}\left(x_{j} P_{j}+y_{j} Q_{j}\right)\right] \prod_{j=1}^{n} d x_{j} d y_{j} .\end{gathered}\]