The idea for this book grew out of proposals at the APL86 con- ference
in Manchester which led to the initiation of the I-APL (International
APL) project, and through it to the availability of an interpreter which
would bring the advantages of APL within the means of vast numbers of
school children and their teachers. The motivation is that once school
teachers have glimpsed the possibilities, there will be a place for an
"ideas" book of short programs which will enable useful algorithms to be
brought rapidly into classroom use, and perhaps even to be written and
developed in front of the class. A scan of the contents will show how
the conciseness of APL makes it possible to address a huge range of
topics in a small number of pages. There is naturally a degree of
idiosyncrasy in the choice of topics - the selection I have made
reflects algo- rithms which have either proved useful in real work, or
which have caught my imagination as candidates for demonstrating the
value of APL as a mathematical notation. Where appropriate, notes on the
programs are intended to show the naturalness with which APL deals with
the mathematics concerned, and to estab- lish that APL is not, as is
often supposed, an unreadable lan- guage written in a bizarre character
set.