Dick Lathwell

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Richard Henry Lathwell was one of the implementers of APL\360, and a designer and implementer at IBM and I.P. Sharp Associates afterwards. He is credited with the practical realization of shared variables in APL.SV, and also published the modern formula for tolerant comparison,[1] and assisted in the creation of the first APL standard, ISO 8485:1989.[2]

Lathwell was born in Calgary, and studied at the University of Alberta, graduating with a B.Sc. in mechanical engineering in 1965. He met Ken Iverson in 1963 and learned Iverson Notation in the same time period. Lathwell was hired by IBM's Watson Research Center in 1966 to work with Iverson, where he implemented APL\360 with Larry Breed and Roger Moore. Later he worked on the design of shared variables, implementing a prototype of APL.SV in 1971 (the full release followed in 1973). He also worked on APL 5100 and defined tolerant comparison at IBM. In October 1977 Lathwell left to work in the I.P. Sharp Associates System Design Group ("the Zoo").[3] At IPSA, he organized the 1978 IPSA conference,[4] and designed and implemented interfaces to SHARP APL. He was appointed product manager for operating systems and auxiliary processors in 1982 and manager of the Research and Development Group in 1984.[5]

In 1973 the ACM awarded Lathwell, Larry Breed, and Roger Moore the Grace Murray Hopper Award "for their work in the design and implementation of APL\360, setting new standards in simplicity, efficiency, reliability and response time for interactive systems."[6]

Lathwell's daughter Catherine has been involved in documenting APL history.



  1. Dick Lathwell. APL comparison tolerance at APL76 (also reproduced in SATN-23).
  2. Adin Falkoff and D. L. Orth. "Development of an APL standard" at APL79.
  3. IPSA Newsletter December 1977 (pdf)
  4. IPSA Newsletter November/December 1978 (pdf)
  5. IPSA Newsletter July/August 1984 (pdf)
  6. Association for Computing Machinery. 1993 Grace Murray Hopper Award. Accessed 2021-05-29.

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