Origins

Abstract

Computers perform logical tasks—numerical calculation and symbol arranging. A procedure for carrying out such a task is sometimes called an algorithm. (The dictionaries say the word ought to be “algorism” and it means the Arabic decimal system of arithmetic, named after an Arabic mathematician of the ninth century A.D.; but with spelling and meaning just stated the word is widely used in computing circles.) A precise specification of an algorithm, especially one so coded that it may be followed by a computer, is also called a program. A program consists of a sequence of statements or commands; some statements specify one or more entities in terms of operations on other entities; other statements, known as branches, specify which statement shall next be executed. A set of statements that are executed repeatedly, because a branch at the end returns execution to the beginning of the set, is called a loop.