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Kenneth E. Iverson

Kenneth Eugene Iverson
Born (1920-12-17)December 17, 1920
Camrose, Alberta, Canada
Died October 19, 2004(2004-10-19) (aged 83)
Toronto, Ontario, Canada
Citizenship Canadian
Fields Computer Science
Institutions Harvard University
Alma mater Queen's University
Harvard University
Doctoral advisor Wassily Leontief and Howard Aiken
Known for Programming languages: APL, J
Notable awards IBM Fellow
Harry H. Goode Memorial Award (1975)
Turing Award (1979)
Computer Pioneer Award

Kenneth Eugene Iverson (17 December 1920 – 19 October 2004) was a Canadian computer scientist noted for the development of the APL programming language in 1962. He was honored with the Turing Award in 1979 for his contributions to mathematical notation and programming language theory. The Iverson Award for contributions to APL was named in his honor.


  • Life 1
  • Work 2
  • Awards 3
  • Major publications 4
  • See also 5
  • References 6
  • External links 7
    • Obituaries 7.1


Ken Iverson was born on December 17, 1920 in Camrose, a city in central Alberta, Canada. His parents were farmers of Norwegian descent who came to Alberta from North Dakota. While he showed an early aptitude for mathematics, teaching himself calculus while a teenager, he left school after the 9th grade to work on his parents' farm. However, during World War II, while he served in the Royal Canadian Air Force, he qualified for a high school diploma by taking correspondence courses. After the war, he was able to enter Queen's University in Kingston, Ontario and graduated in 1950 with a Bachelor's degree in Mathematics and Physics.

Continuing his education at Harvard University, he received a Master's degree in 1951 in Mathematics and started working with Howard Aiken and Wassily Leontief. Howard Aiken had developed the Harvard Mark I, one of the first large-scale digital computers, while Wassily Leontief was an economist who was developing the input-output model of economic analysis, work for which he would later receive the Nobel prize. Leontief's model required large matrices and Iverson worked on programs that could evaluate these matrices on the Harvard Mark IV computer. Iverson received a Ph.D. in Applied Mathematics in 1954 with a dissertation based on this work.

Iverson stayed at Harvard as an assistant professor for the next five years, but failed to get tenure.

Iverson was hired by IBM in 1960 to develop his notation into a programming language for the IBM System/360.

In 1980, Iverson left IBM for I. P. Sharp Associates, a leading Canadian APL timesharing company, where he, among other things, participated in the further development of the APL programming language. In 1987 he retired from I. P. Sharp.

In the summer of 1989, Roger Hui and Arthur Whitney, along with Iverson, produced a short prototype interpreter which would later be the seed for the J language, a variant of APL. Iverson and Roger Hui would continue collaborating on J for the next 15 years.

Ken Iverson died of a stroke on October 19, 2004 at the age of 83.


Iverson developed a mathematical notation that became known as Iverson Notation for manipulating arrays that he taught to his students, and described in his 1962 book A Programming Language.[1] In 1960, he began work for IBM and working with Adin Falkoff, created APL based on the notation he had developed. He was named an IBM Fellow in 1970.[2]

In late 1989, Ken Iverson and Roger Hui began collaboration on an advanced continuation of an APL-like language which they called J, first demonstrated publicly at the APL90 conference the next year.[3] The improvements were intended to fix some of the persistent character set issues that plagued APL since its inception, and to add new advanced features such as functional programming, arrays of variables, and support for parallel MIMD operations, some of which do not appear in APL today. It was intended that the J language be an improvement over existing APL. The J interpreter and language continue to evolve today. A version is available from J Software under the GPL3 license.[4]


Major publications

  • —— (1962). A Programming Language. John Wiley and Sons.  
  • ——;  
  • ——;  
  • —— (1966). Elementary Functions: an algorithmic treatment. Science Research Associates. 
  • ——;  
  • —— (January 1972). "APL in Exposition" (PDF). IBM Philadelphia Scientific Center (IBM). Tech. Report No. 320-3010. Retrieved 2013-09-06. 
  • ——;  
  • ——;  
  • —— (August 1980). "Notation as a tool of thought".  
  • ——;  
  • —— (1990). Tangible Math. Iverson Software. 
  • —— (1991). "A personal view of APL". IBM Systems Journal 30 (4): 582–593.  
  • —— (1991). The ISI Dictionary of J. Iverson Software. 

See also


  1. ^ John Wiley & Sons, ISBN 0-471-43014-5
  2. ^ Citation in Corporate Technical Recognition Event (CTRE) booklet, 3 June 1997
  3. ^ Iverson, K. E.;  
  4. ^ J Software Source Code page

External links

  • Papers by Kenneth E. Iverson from Jsoftware website
  • An Autobiographic Essay (Vector, vol 23, No 4, 15 pages)
  • Short Biography at the website


  • Ehud Lamm's obituary at Lambda the Ultimate
  • Remembering Kenneth E. Iverson Memorial issue of Vector, the Journal of the British APL Association
  • A Celebration of the life of Kenneth Eugene Iverson
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