Number systems
In this section, we introduce notation for describing sets of numbers. We will focus on the real numbers and the complex numbers.
Notation for numbers and fields
As this is a book about data science, we will be dealing with numbers. So, it will be worthwhile recapping the notation we use to refer to the most common sets of numbers.
Most of the numbers we will deal with in this book will be real numbers, such as 4.6, 1, or -2.3. We can think of them as “living” on the real number line shown in Figure 1.1. The real number line is a one-dimensional continuous structure. There are an infinite number of real numbers. We denote the set of all real numbers by the symbol ℝ.
Figure 1.1: The real number line
Obviously, there will be situations where we want to restrict our datasets to, say, just integer-valued numbers. This would be the case if we were analyzing count data, such as the number of items of a particular...
