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spence() double spence ( double  x ) Spence's function (dilogarithm) Li2(x) Purpose spenc computes a Spence's function (dilogarithm). Li2(x) = ∫ -ln(1-t)/t dt [0, x] Returns Spence's function Li2(x). Parameters [in] x Argument x. Error handling Range error (ERANGE) may occur.