\[f(x)=\frac{1}{2\pi\mathrm{i}}\int^{\sigma+\mathrm{i}\infty}_{\sigma-\mathrm{i}%
\infty}x^{-s}\mathscr{M}\mskip-3.0muf\mskip 3.0mu\left(s\right)\,\mathrm{d}s.\]