This topic provides basic details on a number of mathematical functions that arise in statistical formulas. These include Bessel functions of the first kind (standard and modified versions), the Gamma function, and a number of other useful functions, such as the Logistic and Gompertz. In addition a number of information theoretic measures are described. These cover complexity and diversity measures, together with a number of special statistics or criteria that are used to measure the relative 'quality' of alternative models (AIC/BIC and MDL criteria). Finally this topic describes the basic procedures involved in matrix algebra, which provides a central aspect of many statistical techniques, especially in multivariate analyses and regression models.