Introduction

A defined function is a program that takes 0, 1, or 2 arrays as arguments and may produce an array as a result.

A defined operator is a program that takes 1 or 2 functions or arrays (known as operands) and produces a derived function as a result.

To simplify the text, the term operation is used within this chapter to mean function or operator.

Dyalog provides two types of operations:

• Traditional Functions and Operators; the original user-defined functions and operators that are part of the APL standard.
• Dfns and Dops which are unique to Dyalog.