\[\frac{1}{\pi}\int^{\pi}_{-\pi}f(x)\overline{g(x)}\,\mathrm{d}x=\tfrac{1}{2}a_{%
0}\overline{a_{0}^{\prime}}+\sum^{\infty}_{n=1}(a_{n}\overline{a^{\prime}_{n}}%
+b_{n}\overline{b^{\prime}_{n}}),\]