Spence's Function

$\begin{figure}\begin{center}\BoxedEPSF{SpencesFunction.epsf scaled 800}\end{center}\end{figure}$

$\begin{displaymath} F(x)\equiv \int_0^x {\ln(1+t)\over t}\, dt. \end{displaymath}$

References

Berestetskii, V. B.; Lifschitz, E. M.; and Ditaevskii, L. P. Quantum Electrodynamics, 2nd ed. Oxford, England: Pergamon Press, p. 596, 1982.