An interview with C. W. “BILL” GEAR Conducted by Thomas Haigh On September 17-19, 2005 In Princeton, New Jersey Interview conducted by the Society for Industrial and Applied Mathematics, as part of grant # DE-FG02-01ER25547 awarded by the US Department of Energy. Transcript and original tapes donated to the Computer History Museum by the Society for Industrial and Applied Mathematics © Computer History Museum Mountain View, California ABSTRACT Numerical analyst Bill Gear discusses his entire career to date. Born in London in 1935, Gear studied mathematics at Peterhouse, Cambridge before winning a fellowship for graduate study in America. He received a Ph.D. in mathematics from the University of Illinois, Urbana-Champaign in 1960, under the direction of Abraham Taub. During this time Gear worked in the Digital Computer Laboratory, collaborating with Don Gillies on the design of ILLIAC II. He discusses in detail the operation of ILLIAC, its applications, and the work of the lab (including his relationships with fellow graduate student Gene Golub and visitor William Kahan). On graduation, Gear returned to England for two years, where he worked at IBM’s laboratory in Hurlsley on computer architecture projects, serving as a representative to the SPREAD committee charged with devising what became the System 360 architecture. Gear then returned to Urbana-Champaign, where he remained until 1990, serving as a professor of computer science and applied mathematics and, from 1985 onward, as head of the computer science department. He supervised twenty two Ph.D. students, including Linda Petzold. Gear is best known for his work on the solution of stiff ordinary differential equations, and he discusses the origins of his interests in this area, the creation of his DIFSUB routine, and the impact of his book “Numerical Initial Value Problems in Ordinary Differential Equations” (1971). He also explores his work in other areas, including seminal contributions to the analysis of differential algebraic equations and work in the 1970s an ambitious system for generalized network simulation. Gear wrote several successful textbooks and was active in ACM’s SIGNUM and SIGRAPH, served as SIAM President and a member of the ACM Council as well as a number of blue ribbon panels and scholarly societies. In 1990 Gear left Illinois, to become one of the founding vice presidents of NEC’s new Research Institute in Princeton, New Jersey. From 1992 until his retirement in 2000 he was president of the institute, and he discusses his work there, the institute’s place within NEC, and its accomplishments and problems. HAIGH: Thank you very much for agreeing to take part in the interview. It’s always nice to come to Princeton. I wonder if I could begin by asking you, in general terms, about your family background. GEAR: Well, I was born in 1935 in the period before the war in a suburb of London. My father was very much working-class. I think by that time he may have been a foreman of the operation he was running. He had left school I think at fourteen, which was typical of his class in those days. His grandfather left school I believe at twelve or ten (I can’t remember) and gone to work as a laborer in a factory. I think there are two important things about my father. One was I think he had a tremendous moral-ethical sense about certain things, which he pushed on me, about the need to treat people properly. The other thing that he was always hammering into me was how I had to get an education—he said I had to get it because he didn’t want me to work like he had to work though his life. That was odd because, when I finally became a faculty member at Illinois and my father came over and visited, he couldn’t understand why I seemed to work all the time—he thought the reason to get an education was that someone then took it easy. Of course that’s the great thing about working at the university: if you’ve got a job you really like, it’s not work at all. It’s the thing you probably enjoy most of all. Now back to my early background. We lived in a suburb of London built in the early 1930s to house the growing mass of people moving into the London area. I went to the local primary school in that area. Of course, in those days England was unbelievably homogeneous: virtually all white, virtually all English. Immigration hadn’t started yet. It was in the period leading up to the war. In fact, I had only been in local primary school for two weeks when war was declared. I was sent to my grandparents for the first of two trips and spent a year there. HAIGH: And where did they live? GEAR: About 40 miles north of London. Of course in those days, that was a long distance. It was relatively safe in the country from bombing. Then they sent me there again when the V2s were coming in, late 1944, I guess. Other than that I went to the local school and behaved like any typical working-class kid: playing most of the time, avoiding most schoolwork. In those days, I loved mathematics (of course it was called “arithmetic” in those days). I remember sitting in classes doing things like doubling a number as often as I could to see how big it would get. I can remember when I was five I decided to see how high one could count, so every night I would start counting higher and higher, and then I would ask my mother to remember the number so that I could continue from there the next night. I guess I didn’t believe yet in infinity. I’m sure she just gave me an arbitrary number each night [laughs]. That’s better than counting sheep to get to sleep. So it was an uneventful childhood. My father was working class and I suspect money was somewhat limited. We weren’t poor. Even though it was wartime and there was rationing, there was sufficient food for everybody. It may not have been a great diet. So I didn’t see it as a period of privation, although I remember the night when ice cream became available when I was ten years old. And when candy went off ration, I had terrible teeth for a couple of weeks from eating too much candy. HAIGH: Other than things you’ve already mentioned, are you aware of any particular influences that this background had on the way you approached your later career? C.W. Gear 3 GEAR: Well, I think that in the primary school, we probably had one very good teacher in my last year. Let me say a little bit about the educational system in England then, because my father was pushing me very hard in getting an education. He was really worried because at that time, the career path for a normal person of my background was to go to primary school and then to secondary school at age eleven-and-a-bit, which basically prepared you for a blue-collar job. There were a few scholarship positions open to the local grammar schools, which -- although they were state-funded -- most of the positions were fee-paying and were beyond the means of people like my parents. So my father was very concerned that I should try to get a scholarship there, and I think he was pretty pessimistic that I’d do it because I was only interested in mathematics and terrible in other subjects. I remember he used to drill me on general knowledge questions in the evenings to try and get me to learn some stuff. I was very fortunate because in 1945 after the war, the Labor government won and Churchill and the Tories were booted out . I was too young then—I was ten, so I don’t know what was behind all of that. But the Labor government revolutionized many things in the educational system. They made all the positions scholarship; in other words, they got rid of the fees altogether and made them all the subject of what became the “eleven plus” exam. I was part of the first group to take that. So there were many more positions. As I recall, there were three parts to the exam that I took: one was mathematics, which was almost certainly arithmetic which I’m sure I probably aced because I really liked that; one was some sort of English; and the third one was labeled as some sort of general knowledge, my father was desperate because he drilled me on these facts of English history and all sorts of stuff every night and I would never remember it. But in fact it was an IQ test, and most of those things are pretty easy for a mathematician type. So I probably did very well on two of them, and that probably got me over the hurdle. HAIGH: They would call those IQ tests “verbal reasoning,” for some reason. GEAR: Oh, okay, I don’t know. I just remember that instead of questions of fact what I did was little puzzles. So that got me to Harrow County school, the grammar school—not the famous Harrow, but down the hill from it in the cheaper part of town. But it was the best local grammar school. From there things went on up. My ambition at that age was probably to be something like an electrician, because I loved technology, I loved taking old radios apart and trying to rebuild them in some way, I loved mechanical things.