## 4 Data Types

This chapter discusses the various types of objects that can be placed
on the Calculator stack, how they are displayed, and how they are
entered. (See Data Type Formats, for information on how these data
types are represented as underlying Lisp objects.)

Integers, fractions, and floats are various ways of describing real
numbers. HMS forms also for many purposes act as real numbers. These
types can be combined to form complex numbers, modulo forms, error forms,
or interval forms. (But these last four types cannot be combined
arbitrarily: error forms may not contain modulo forms, for example.)
Finally, all these types of numbers may be combined into vectors,
matrices, or algebraic formulas.