Chapter 5. Math

In other programming languages, numbers are primitives, or basic building blocks, that are used by other objects to create logic. In Ruby, everything (almost) is an object, even numbers. For example, here are some numbers that are considered primitives by other languages. What classes do they come from?

2.class # => Fixnum
2.0.class # => Float
2_000_000_000.class # => Bignum

There’s the proof in living code: Ruby does turn almost everything into an object. (The underscores in the last number, by the way, are just there for readability; the Ruby interpreter ignores them.)

Ruby has a number of classes and modules related to numbers. Here are the more important ones:


The base class for numbers


The basic integer class, and the basis for the Fixnum class


The class for real or floating-point numbers, based on the computer’s native capacity to represent double-precision


The main integer class, based on what the computer can hold in a native machine word, such as 32 bits or 64 bits, minus 1


The class of integers outside the range of the basic, native machine word


A module that holds math functions (as methods)


A module for approximating the precision of real numbers


A class that represents fractional numbers


A class that represents complex numbers, which extend real numbers with imaginary numbers (x + iy)


A class for creating mathematical matrixes

A hierarchy of the math classes, along with modules, is shown in Figure 5-1 ...

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