Common Lisp the Language, 2nd Edition Several kinds of numbers
are defined in Common Lisp. They are divided into integers;
ratios; floating-point numbers, with names provided for up to
four different floating-point representations; and complex
numbers. X3J13 voted in March 1989 (REAL-NUMBER-TYPE) to add the
type real. The number data type encompasses all kinds of
numbers. For convenience, there are names for some subclasses of
numbers as well. Integers and ratios are of type rational.
Rational numbers and floating-point numbers are of type real.
Real numbers and complex numbers are of type number. Although
the names of these types were chosen with the terminology of
mathematics in mind, the correspondences are not always exact.
Integers and ratios model the corresponding mathematical
concepts directly. Numbers of type float may be used to
approximate real numbers, both rational and irrational. The real
type includes all Common Lisp numbers that represent
mathematical real numbers, though there are mathematica