The dilogarithm Li_2(z) is a special case of the polylogarithm Li_n(z) for n = 2. Note that the notation Li_2(x) is unfortunately similar to that for the logarithmic integral Li(x). There are also two different commonly encountered normalizations for the Li_2(z) function, both denoted L(z), and one of which is known as the Rogers L-function. The dilogarithm is implemented in the Wolfram Language as PolyLog[2, z].