A Time of Giants: Remembering Robert ‘Bob’ Skeel and the Impactful Numerical Analysis Group | Computer science


The hearing of former computer science professor Robert “Bob” Skeel of Illinois at the age of 73 saddened many of his former colleagues and students who knew him well.

Robert “Bob” Skeel

However, it also gave these people the opportunity to remember its effect – achieved through technically brilliant research and a calm, rational and helpful demeanor.

Skeel was a faculty member at Illinois CS from 1974 to 2004, and his presence here dates back to the origins of the department. Based on a reorganization of the Digital Computer Laboratory (DCL) – when elements from mathematics, electrical engineering and physics merged into one unit – the Illinois CS department began in 1964.

That same year, Abraham H. Taubs graduated as head of the DCL, and one of his PhD students was C. William Gear – a pioneer in numerical analysis and later head of the CS department.

The numerical analysis group grew under Gear’s influence, and one of the people added to the faculty was Skeel. This created a core group of the Illinois CS faculty, which influences almost all areas of computer research conducted here.

The next stage in growth for this group was another longtime professor, Michael T. Heath, who worked closely with Skeel.

“When I came here in 1991 there was a large group of professors, including Bob Skeel. I quickly realized that we had a lot in common, ”said Heath. “We taught some of the same courses, took proficiency tests together, and served on graduation commissions for each other’s students.

“I joined a very respectable group and I think I have contributed to the reputation myself. But it was undoubtedly a golden era because of people like Bob. “

Citing the influence of these notable scientists, Nancy M. Amato, the current director of the Illinois CS, believes numerical analysis – now included in a research area called Scientific Computing – remains an integral part of the department.

“I remember Bob from my college days – that was definitely a time of giants in numerical computation for the faculty,” said Amato, an important cornerstone of the overall strength of our program. “

Heath called Skeel a “First Class Theorist” and was also impressed by his former colleague’s ability to bring himself beyond those skills into practical applications.

Skeel, pictured here in his office, was influential through his expertise in numerical analysis, but also immersed himself in application-related projects.
Skeel, pictured here in his office, was influential through his expertise in numerical analysis, but also immersed himself in application-related projects.

“I respected the fact that Bob was willing and able to roll up his sleeves when facing real-world problems,” said Heath. “Bob proved some very interesting theorems, which I cited many times in my own classes, to show students that CS in Illinois was an important contributor to their knowledge.

“But he also dived directly into the NAMD project, which spawned one of the world’s leading – possibly the most significant – efforts in parallel code for molecular dynamics.”

Work on this project was carried out by an interdisciplinary team known as the Theoretical and Computational Biophysics Group, which was founded at the Beckman Institute. These included Skeel and Laxmikant “Sanjay” Kale from Illinois CS and physicist Klaus Schulten, who worked at the Beckman Institute.

Kale called it the “most successful example of interdisciplinary work” he has been involved in during his career.

“Bob’s numerical analysis skills stand on their own, but he also had a solid understanding of how to make new and cutting-edge arguments around coding and programming languages,” said Kale. “Klaus was already very well established in molecular simulation, so that his advisor later received the Nobel Prize for his work in this area. And Bob made some unique contributions to the numerical methodology that went into NAMD, such as advocating symplectic integrators for long-term energy conservation. “

“It was amazing to bring together all of our diverse skills, expertise, and reach from our various communities to develop a parallel, object-oriented molecular dynamics code designed for high-performance simulation of large biomolecular systems.”

Kale and Heath both said that Skeel was a man of few words, but he made those words count.

Stephen Bond, another former colleague of his and Illinois CS professor from 2003 to 2010, said that he first met Skeel at a conference. The two had a colleague in common, and that first interaction became another bond when Bond was a postdoctoral fellow at the University of California at San Diego. At the same time, Skeel took a sabbatical there.

Bond, now Senior Member of Technical Staff at Sandia National Laboratories, recalled how Skeel was instrumental in his start at Illinois CS. Their working relationship went so well that it lasted almost to Skeel’s death.

“Bob has always been very nice, especially to people who are less established in the field,” said Bond. “He has always been very encouraging to students and junior professors, especially when he was impressed with their presentations and research. Everything he did was in the long-term interest of the group and his students. And people listened to him.

“He visited me at Sandia in March 2020 and gave a well-attended presentation on recent research in the presence of many former Illinois CS students who now work at Sandia.”

Skeel leaves behind his wife Marjorie, two daughters, their spouse and four grandchildren. A private family memorial service was held on November 5th at the Anglican Christ Church in Phoenix. A full obituary can be found here.


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