The elementary functions are defined initially from a list of core functions.The definition continues with a recursive formulation, building more elementary functions from previously defined elementary functions by using arithmetic operations, composition of functions, and inverting functions.
It was covered first in the section on linear functions, specifically in Subsection LF.INV: Inverse of a Linear Function.In fact, inverse functions have been discussed in almost every section of this resource!
QF.INV "Inverse" of a Quadratic Function
OW.ICPPF Inverse for Core Positive Power Functions
ELF.CELF Core Exponential and Logarithmic Functions
ELF.INV Inverses for Exponential and Logarithmic Functions
TRIG.INV Inverses for Trigonometric Functions