# Eugene McDonnell

**Eugene Edward McDonnell** (October 18, 1926 – August 17, 2010) was an APL implementer and designer, and popularizer of APL and J. He edited the APL Quote-Quad column "Recreational APL" and wrote the "At Play with J" series of articles for Vector journal, and received the Iverson Award in 1987.

McDonnell, a programmer since 1954, joined IBM and first learned about Iverson notation in 1961, and joined Ken Iverson's group at IBM in 1968.^{[1]} He left IBM for I.P. Sharp Associates in 1978, where he worked under Eric Iverson.^{[2]}

## Contributions to APL and J

McDonnell suggested the symbol `×`

for Signum and designed the Circle function (`○`

) as a way to unify trigonometric and hyperbolic functions^{[3]}. He designed APL's complex Floor^{[4]} and suggested the extension of Or (`∨`

) and And (`∧`

) to GCD and LCM^{[5]}. He was also involved in the introduction of complex numbers to SHARP APL^{[6]}. His suggestion that zero divided by zero should be zero rather than one^{[7]} was later adopted by J.

In 1988, McDonnell and Ken Iverson developed function train notation, one of the major innovations that spurred the creation of J.

## External links

- Eugene McDonnell
- JSoftware paper collection (includes links to Recreational APL and At Play with J articles)
- "At Play With J", updated by the J community
- Eugene McDonnell Quotations and Anecdotes assembled by Roger Hui

## References

- ↑ Anon.
*Candidates for STAPL Offices*(excerpt). APL Quote-Quad, Volume 7, Number 4, Winter 1977. - ↑ Hui, Roger. "Eugene McDonnell Quotations and Anecdotes".
- ↑ McDonnell, Eugene. "The Story of ○".
- ↑ McDonnell, Eugene. "Complex Floor".
- ↑ McDonnell, Eugene. "A Notation for the GCD and LCM Functions".
- ↑ McDonnell, Eugene. SATN-40: Complex Numbers.
- ↑ McDonnell, Eugene. "Zero Divided by Zero".