1 Introduction
2 Mathematics is not only about computing
3 Basic concepts
4 Elementary functions
4.1 What is it a function?
4.2 The absolute value
4.3 Lower and upper integer part
4.4 Linear function
4.5 Quadratic function
4.6 Polynomial function
4.7 Roots
4.8 Rational function
4.9 Trigonometric functions
4.10 Exponantiation and logarithm
5 Analytical geometry
6 Warning
7 List of the used symbols
Index
Bibliography

In this chapter we first discuss the concept of function and further summarize the properties of several known types of real functions of a real variable $f$.