Kenneth E. Iverson

Kenneth Eugene " Ken " Iverson ( born December 17, 1920 in Camrose, Alberta; † 19 October 2004 in Toronto, Ontario) was a Canadian mathematician and computer scientist who developed the programming language APL and J.


Iverson grew up on a farm in rural Alberta. Four months after his fifth birthday, he was enrolled in a school consisting of one room and one teacher. He skipped several classes and changed the age of twelve in the ninth grade of a nearby village school, which he broke off during the tenth grade to work on the farm. Besides, he took a course in electrical engineering. In 1942 he was drafted into the Royal Canadian Air Force. During the Second World War, he took eight correspondence courses of the Royal Canadian Legion and was convinced of his comrades from his studies. After his release in 1946 he went to Queen's University in Kingston, Ontario, in 1950 and made his BS in mathematics and physics, and at Harvard University in Cambridge, Massachusetts, finally in 1951 the Master in Applied Mathematics as well as in 1954 in Howard Hathaway Aiken Ph. D. in Applied Physics. From 1955 to 1960 he taught at Harvard University as an assistant professor of applied mathematics, where he was also the first Master's course for computer science ( Automatic Data Processing ) built with Aiken, Fred Brooks, and others.

Then he worked in the research department of IBM, where he worked until 1980. From 1980 he worked for the time-sharing service IP Sharp Associates in Toronto, before he went into retirement in 1987, he spent intensively searching and developing further.


During his tenure at Harvard University Kenneth E. Iverson had developed his own notation for dealing with arrays, which he successfully started in teaching. In his six-month sabbatical in 1957 at McKinsey & Company, he had been able to use it. At IBM Research, he built the notation of a formal language and published them in 1962 in the book A Programming Language, which is published by John Wiley. He developed language, named after the book title APL, was first used for the formal description of computer IBM System/360 family that has significantly contributed to the great success of IBM in 1964. 1965, the first APL interpreter for batch processing has been completed, which APL was to an executable programming language. In 1966, the interactive system APL \ 360, which became the basis for all other APL interpreter. Various IBM computers were also available with specially adapted to APL keyboards. Kenneth E. Iverson was involved along with Adin Falkoff instrumental in the development of these systems. Among other things, he also has the IBM Philadelphia Scientific Center for the further development of APL co-founded. Later, he designed several programming languages ​​that further developments and improvements of APL represent, including from 1990 with Roger Hui language J.

He, too, are the floor and ceiling bracket, ie the notation for the floor and the ceiling function. In addition, the often related in theoretical computer science illustration of a predicate to a single-digit binary number to obtain for complex problems closed formulas (see Figure predicate ).


For the development of APL and for his contributions to the implementation of interactive systems Kenneth E. Iverson was in 1979 awarded the Turing Award by the ACM. In 1982 he received the Pioneer Award of the IEEE, 1991, the National Medal of Technology, USA. He was a member of the National Academy of Engineering of the United States. In 1970 he was appointed IBM Fellow.


  • A Programming Language. Wiley, New York, 1962.
  • By Frederick P. Brooks: Automatic Data Processing. Wiley, New York, 1963.